Lipid Peroxidation In Red Blood Cells Research Articles

Molecular docking and in vivo protective effects of okra (Abelmoschus esculentus) against metabolic dysfunction in high-fat, high-sodium diet-fed rats.

Okra pods (Abelmoschus esculentus L. Moench) have been used as a functional vegetable as they contain polysaccharides, flavonoids, and other bioactive molecules that protect the body from several chronic diseases. The purpose of this study was to look at the involvement of okra constituents (mucilage and flesh) in the prevention of metabolic dysfunctions induced in a rat model by a high-fat, high-salt (HF/NaCl) diet. Okra mucilage was extracted using an ultrasonic method, freeze-dried, characterized using Fourier transform infrared (FTIR) and scanning electron microscopy (SEM), and tested for swelling ratio and radical scavenging activity. Okra flesh (skin and seeds) was separated from pods; characterized using SEM; and tested for dietary fiber content, phenolic profile, and radical scavenging activity. The significance of okra bioactive compounds in inhibiting human salivary amylase, glutamine : fructose-6-phosphate amidotransferase (GFAT), tumor necrosis factor-alpha (TNF-α), and C-reactive protein (CRP) was investigated using molecular docking. Rats were fed an HF/NaCl diet and orally treated daily with freeze-dried okra mucilage or flesh (100 mg per kg body weight) for 8 weeks. Glucose, insulin, inflammatory indicators (CRP, TNF-α, and interleukin 6), oxidative markers (red blood cell lipid peroxidation, glutathione peroxidase, nitric oxide, and superoxide dismutase), lipid profile, estradiol, feces lipids as well as femur and urine calcium were measured. The molecular docking findings showed the interaction of quercetin and chlorogenic acid, which are the most abundant phenolic compounds in okra pods, with the studied proteins, which gives an indication of the mechanism of okra's anti-diabetic, anti-oxidant, and anti-inflammatory effects. Okra mucilage and flesh significantly reduced glucose, insulin, cholesterol, lipid peroxidation, CRP, TNF-α, IL-6, and urine calcium levels while significantly increasing feces lipid and femur calcium levels. The findings suggested that okra mucilage and flesh seem to be promising candidates for protection against metabolic dysfunction.

Biliverdin Reductase B Protects Against Primaquine Induced Hemolysis - Identification of a Novel Anti-Oxidant Pathway in Murine Erythrocytes

Background: Biliverdin Reductase B (BlvrB) is the fourth most abundant enzyme in red blood cells (RBCs) and is widely expressed in other tissues. In normal heme catabolism, porphyrin is converted to biliverdin-alpha (by hemoxygenase (HO)) and then reduced to bilirubin-alpha (by biliverdin reductase A (BlvrA)). Bilirubin-alpha is then glucuronidated and excreted. The large body of literature investigating heme metabolism, bilirubin-based pathologies, and the oxidative biology of bilirubin/biliverdin in adults focuses almost exclusively on BlvrA and the alpha isomers of biliverdin and bilirubin. However, porphyrin is a tetrapyrrole with 4 distinct meso-carbon bridges, each of which can be broken to generate a distinct biliverdin isomer (alpha, beta, gamma, or delta). Although HO is exquisitely specific for the alpha-bond (generating only biliverdin-alpha), chemical coupled oxidation of heme yields all four biliverdin isomers. BlvrB (and not BlvrA) can reduce each of non-alpha biliverdin isomers into their corresponding bilirubin isomers (bilirubin-beta is prevalent in neonatal jaundice and kernicterus). BlvrB also reduces flavins and additional quinone metabolites. Despite BlvrB's abundance and evolutionary conservation, its only known function is a subtle effect on hematopoietic lineage fate (megakaryocyte vs. erythroid). BlvrB has no known function in mature RBCs. We hypothesized that BlvrB plays an important antioxidant role that would only become obvious when other redundant anti-oxidant pathways were limited. Methods: A novel BlvrB knockout mouse was generated on a C57BL/6 background. A model of primaquine (PQ) induced oxidative hemolytic anemia in G6PD deficient mice was used as a clinically relevant scenario in which compromised antioxidant biology leads to treatment limiting pharmacotoxicity in RBCs. BlvrB-KO mice were crossed with two strains of mice that had murine G6PD replaced with either the A- deficient variant of human G6PD (hG6PD(A-)) or the non-deficient form of human G6PD (hG6PD(ND)). Four mouse strains (i.e., hG6PD(ND) and hG6PD(A-) mice with or without BlvrB deletion) received either a 4-day course of PQ or control PBS injections. Anemia was monitored by hematocrit (HCT). Reticulocyte count (RET) was monitored by flow cytometry as CD71+, thiazole orange+ erythrocytes. Peripheral blood was subjected to high resolution metabolomics to elucidate biochemical changes. Results: All mouse strains were healthy at baseline, with normal measured hematological parameters (i.e., Hct 40, RET 1.5%). No change in HCT or RET was observed in hG6PD(ND) or BlvrB-KOxhG6PD(ND) mice receiving PQ or in any strain receiving PBS. PQ induced hemolytic anemia in hG6PD(A-) mice, with an average HCT of 32.7 (18% drop) with RET of 3.1%. A significant exacerbation of PQ induced hemolysis was observed in BlvrB-KOxhG6PD(A-) mice that had an average HCT of 22.5 (44% drop) with RET of 5.3%. (n= 11 mice per group, p <0.001 between groups). Blood from PQ-treated hG6PD(A-)xBlvrBKO mice showed defective glycolysis at the level of glyceraldehyde 3-phosphate dehydrogenase, increased levels of multiple long-chain acylcarnitines, altered redox metabolism, and specific increases of hypoxanthine and sphingosine-1-phosphate (S1P). Three separate experiments were performed with similar results. Discussion: These data demonstrate that BlvrB deletion exacerbates oxidative injury and suggest that BlvrB provides a novel and hitherto undescribed antioxidant pathway in RBCs. Because approximately half a billion humans exhibit some form of G6PD deficiency, these data are also directly relevant to a large population of humans, which were modeled using hG6PD(A-) mice. These studies also define the metabolic lesion in peripheral blood. For example, GAPDH is well known to be highly sensitive to inactivation by oxidative damage, resulting in impaired glycolysis. Changes in hypoxanthine and S1P are known to be associated with decreased RBC function and survival. Finally, altered carnitine metabolism is associated with repair of lipid peroxidation in RBCs via the Lands Cycle. Although the mechanism by which BlvrB facilitates antioxidation is not yet clear, we hypothesize it involves redox cycling of non-alpha isomers of biliverdin and bilirubin. However, the mechanisms may be through reduction of flavins and/or other endogenous substrates. Ongoing studies are testing these hypotheses.

Adaptation of Piglets Using Different Methods of Stress Prevention.

Simple SummaryStressful events play a major negative role in the modern technology of weaned piglets. These events include but are not limited to weaning itself, lack of maternal milk, loss of maternal bonding, mixing of different litters, transportation to growing-finishing farms, and housing conditions. Various additives (phenazepam, aminazine, vitamins E and C, the extract Eleutherococcus senticosus, and ultraviolet irradiation) at different doses and combinations with or without ultraviolet irradiation were used to evaluate their effect on the viability and growth rate of piglets after weaning. Content of lipids in the blood and liver, antioxidant activity (AOA) and lipid peroxidation (LPO) significantly decreased or increased with the use of the additives. Feeding a mixture of additives increased survival rate, average daily gain, and live weight at the end of the experiment.The purpose of this study was to evaluate the viability and growth rate of piglets after weaning, the content of lipids in the blood and liver, antioxidant activity (AOA) and lipid peroxidation (LPO) when various additives are used in feed. The experiments were performed on two crosses of piglets obtained from Large White breed sows and Landrace breed boars. Twenty to 28 animals were randomly assigned per group. The following additives were tested: the benzodiazepine phenazepam, the neuroleptic aminazine, vitamins E and C, and the extract Eleutherococcus senticosus (Araliaceae). Different doses and combinations of the additives against ultraviolet irradiation were used. The addition of these substances improved the growth rate and viability of piglets. AOA increased under the influence of all factors studied, especially with the addition of extract of Eleutherococcus in feed in combination with aminazine and UV-irradiation (p < 0.01). However, the addition of Eleutherococcus extract and aminazine intensified LPO (p < 0.01), but use of UV irradiation helped to decrease LPO values (p < 0.01). Feeding a mixture of additives per pig per day of 3 mL of Eleutherococcus extract, 80 mg of 25% tocopherol, and 500 mg of ascorbic acid increased survival rate, average daily gain, and live weight at the end of the experiment. Thus, the use of prophylactic antistress and sedative drugs during weaning helps AOA normalize LPO of red blood cells; enhance post weaning growth of the pigs by 4.8% to 24.6% and increases piglet survival rate by 5% to 5.1%.

Does quercetin protect human red blood cell membranes against γ-irradiation?

ObjectivesRadioprotective potential of quercetin, a powerful free radical scavenger, was investigated in human red blood cells (RBCs) and in isolated RBC membranes exposed to γ-irradiation-induced oxidative stress.MethodsRBCs and RBC membrane suspensions were irradiated (50 Gy) in the presence of quercetin (2–50 µM). Oxidative damage of the membranes was analysed by protein carbonyl measurement (enzyme-linked immunosorbent assay). In RBCs, the concentration of glutathione (GSH) was determined. Lipid peroxidation in RBCs, and for comparison in plasma and peripheral lymphocytes, was quantified by the amount of thiobarbituric acid-reactive substances (TBARS). Radiation-induced damage of the RBC membrane integrity was evaluated by the degree of haemolysis.ResultsQuercetin (50 µM) brought back the level of carbonyls to normal in γ-irradiated RBC membrane proteins and inhibited radiation-induced lipid peroxidation in plasma and lymphocytes, by 75 and 96%, respectively. However, it moderately decreased reduced/oxidized glutathione (GSH/GSSG) ratio and significantly increased TBARS concentrations, by 60 and 28% in irradiated and non-irradiated RBCs, respectively. Haemolysis rate was much higher in RBCs irradiated in the presence of quercetin vs. non antioxidant.DiscussionIn non-cellular systems (RBC membranes or plasma) and in lymphocytes, quercetin shows antioxidative/radioprotective activity but in whole RBCs it acts as a pro-oxidant and a cytotoxic substance. The possible mechanisms of such action are discussed.

Oxidative stress and anxiety-like symptoms related to withdrawal of passive cigarette smoke in mice: Beneficial effects of pecan nut shells extract, a by-product of the nut industry

The present study evaluated the role of pecan nut ( Carya illinoensis) shells aqueous extract (AE) against oxidative damage induced by cigarette smoke exposure (CSE) and behavioral parameters of smoking withdrawal. Mice were passively exposed to cigarette smoke for 3 weeks (6, 10, and 14 cigarettes/day) and orally treated with AE (25 g/L). CSE induced lipid peroxidation in brain and red blood cells (RBC), increased catalase (CAT) activity in RBC, and decreased plasma ascorbic acid levels. AE prevented oxidative damage and increased antioxidant defenses of mice exposed to cigarette smoke. In addition, AE reduced the locomotor activity and anxiety symptoms induced by smoking withdrawal, and these behavioral parameters showed a positive correlation with RBC lipid peroxidation. Our results showed the beneficial effects of this by-product of the pecan industry, indicating its usefulness in smoking cessation.

Effect of Pineal Proteins at Different Dose Level on Fluoride-Induced Changes in Plasma Biochemicals and Blood Antioxidants Enzymes in Rats

Pineal glands secrets melatonin and various proteins and peptides which has many physiological functions. In keeping with this view, present experiment was conducted to know the effect of buffalo (Bubalus bubalis) pineal proteins (PP) at different dose level on fluoride-induced changes in plasma biochemicals and blood antioxidants enzymes in female rats. For this, we took 30 adult female Wistar rats (133-145g body weights, BW) and divided into five groups (control, group I; 150ppm fluoride (F), group II; F+ 50µg pineal proteins, group III; F+ 100µg PP, group IV; F+ 200µg PP, group V). We administered fluoride (150ppm, drinking water) and F+ pineal proteins at 50, 100, and 200µg/kg BW, i.p. daily for 21days. Blood samples were collected at the end of the experiments to estimate plasma glucose, proteins, F, lipid peroxidation (LPO), alkaline phosphatase (ALP), and acetyl cholinesterase (AChE) activity. Red blood cells (RBCs) were separated for analysis of LPO, AChE, catalase (CAT), superoxide dismutase (SOD), reduced glutathione (GSH), glutathione peroxidase (GPx), and glutathione reductase (GR) in different groups of animals. Total plasma glucose and protein level did not significantly change in F-treated rats. Plasma ALP and F level were significantly (p < 0.05) high in group II as compared with control and groups III, IV, and V. Administration of PP at different dose level significantly (p < 0.05) reduced the F concentration and ALP activity. Plasma and RBCs AChE activity was significantly (p < 0.05) reduced in F-treated animals as compared with control rats and significantly (p < 0.05) elevated on exogenous administration of PP (groups III and IV). Plasma and RBCs LPO level was significantly (p < 0.05) high in F-alone-treated rats, and PP caused significant (p < 0.05) reduction of LPO in groups IV and V. However, PP treatment in group IV brought better amelioration of F-induced high LPO than in groups III and V. At no dose level, PP-ameliorated F-induced depression of RBCs GSH, CAT, GR, and GPx level. Interestingly, SOD activity was elevated in dose-dependent manner at different dose level of PP in groups III, IV, and V than control and F-administered rats. These findings clearly indicate the beneficial effects of buffalo pineal proteins on fluoride-induced adverse changes in certain plasma biochemical and blood antioxidant systems of rats. It further indicates that PP has dose-dependent ameliorative function against F-induced adverse effects in plasma and blood.

Effect of levamisole on biological behavior of red blood cells after fracture

Objective To investigate the influence of levamisole (LMS) on the biological behavior of red blood cells (RBC) after fracture, in order to suggest a new strategy for prevention and therapy of traumatic deep venous thrombosis (DVT) . Methods Thirty male rabbits were divided randomly into 2 equal groups, control group A and experimental group B. After anesthesia, fractures were created 3 cm below the entotrochanter and then fixed with plates and screws in both groups. Blood samples were harvested from the 2 groups to analyze blood rheological characteristics respectively at 30 min before operation, 30 min, 1, 4 and 7 days after operation. Malondialdehyde (MDA), rigid index, accumulation index and distortion index, C3b receptor rate (RC3bRR), circulating immune complexes rate (RICR) and natural tumor erythrocyte rosette rate (NTERR) of RBCs were measured. Results RBC immunity: The rates of RC3BRR and NTERR in group B were higher than in the control group (group A) (P < 0.05) at 30 min, 1 and 4 days after operation. However, the rate of RICR was higher in group A than in group B (P < 0.05). There were significant dif-ferences between pre- and post-operation in group A, but not in group B. RBC lipid peroxidation: The post-operative MDA values of RBCs at 30 min, 1 and 4 days in both groups were higher than the preoperative one. The differences were statistically significant (P < 0.05) in group A, but not in group B. The MDA was lower in group B than in group A (P < 0.05). Conclusions Trauma can weaken the RBC immune function, increase the lipid perexidation, and worsen the blood rheological property. LMS can obviously improve the biological behavior of RBC, suggesting it may be useful in prevention and therapy of DVT after fracture. Key words: Immunologic factors; Erythrocyte; Venous thrombosis (DVT); Wounds and traumas; Fracture

Erythrocyte Hemolysis and Hemoglobin Oxidation Promote Ferric Chloride-induced Vascular Injury

The release of redox-active iron and heme into the blood-stream is toxic to the vasculature, contributing to the development of vascular diseases. How iron induces endothelial injury remains ill defined. To investigate this, we developed a novel ex vivo perfusion chamber that enables direct analysis of the effects of FeCl(3) on the vasculature. We demonstrate that FeCl(3) treatment of isolated mouse aorta, perfused with whole blood, was associated with endothelial denudation, collagen exposure, and occlusive thrombus formation. Strikingly exposing vessels to FeCl(3) alone, in the absence of perfused blood, was associated with only minor vascular injury. Whole blood fractionation studies revealed that FeCl(3)-induced vascular injury was red blood cell (erythrocyte)-dependent, requiring erythrocyte hemolysis and hemoglobin oxidation for endothelial denudation. Overall these studies define a unique mechanism of Fe(3+)-induced vascular injury that has implications for the understanding of FeCl(3)-dependent models of thrombosis and vascular dysfunction associated with severe intravascular hemolysis.

Medicinal Values of Fruit Peels fromCitrus sinensis,Punica granatum, andMusa paradisiacawith Respect to Alterations in Tissue Lipid Peroxidation and Serum Concentration of Glucose, Insulin, and Thyroid Hormones

Peel extracts from Citrus sinensis, Punica granatum, and Musa paradisiaca were investigated for their effects on tissue lipid peroxidation (LPO) and on the concentration of thyroid hormones, insulin, and glucose in male rats. In vitro inhibition of H(2)O(2)-induced LPO in red blood cells of rats by 0.25, 0.50, 1.0, and 2.0 microg/mL C. sinensis, P. granatum, and M. paradisiaca peel extracts was observed in a dose-specific manner. Maximum inhibition was observed at 0.50 microg/mL C. sinensis, 2.0 microg/mL P. granatum, and 1.0 microg/mL M. paradisiaca. In the in vivo investigation, out of four different concentrations of each peel extract, 25, 200, and 100 mg/kg C. sinensis, P. granatum, and M. paradisiaca, respectively, were found to maximally inhibit hepatic LPO. The most effective doses were further evaluated for effects on serum triiodothyronine (T(3)), thyroxine (T(4)), insulin, and glucose concentrations. C. sinensis exhibited antithyroidal, hypoglycemic, and insulin stimulatory activities, in addition to inhibition of LPO, as it significantly decreased the serum T(4) (P < .05) and glucose (P < .001) concentrations with a concomitant increase in insulin levels (P < .05). P. granatum decreased LPO in hepatic, cardiac, and renal tissues (P < .01, P < .001, and P < .05, respectively) and serum glucose concentration (P < .01). M. paradisiaca strongly inhibited the serum level of thyroid hormones (P < .01 for both T(3) and T(4)) but increased the level of glucose (P < .05). These findings reveal the hitherto unknown potential of the tested peel extracts in the regulation of thyroid function and glucose metabolism. Besides antiperoxidative activity, C. sinensis extract has antithyroidal, hypoglycemic, and insulin stimulatory properties, which suggest its potential to ameliorate both hyperthyroidism and diabetes mellitus.

Effects of vitamin C infusion and vitamin E-coated membrane on hemodialysis-induced oxidative stress

Chronic hemodialysis (HD) patients manifest anemia and atherosclerosis with associated oxidative stress. We explored whether intravenous infusion of vitamin C (VC) and/or use of vitamin E (VE)-coated dialysis membrane could palliate HD-evoked oxidative stress. Eighty patients undergoing chronic HD were enrolled and randomly assigned into four groups: HD with intravenous VC (n=20), HD with VE-coated dialyzer (n=20), HD with both (n=20), and HD with neither (n=20). We evaluated oxidative stress in blood and plasma, erythrocyte methemoglobin/ferricyanide reductase (red blood cells (RBC)-MFR) activity, plasma methemoglobin, and pro-inflammatory cytokines in these patients. All patients showed marked increases (14-fold) in blood reactive oxygen species (ROS) after HD. The types of ROS were mostly hydrogen peroxide, and in lesser amounts, O2*- and HOCl. HD resulted in decreased plasma VC, total antioxidant status, and RBC-MFR activity and increased plasma and erythrocyte levels of phosphatidylcholine hydroperoxide (PCOOH) and methemoglobin. Intravenous VC significantly palliated HD-induced oxidative stress, plasma and RBC levels of PCOOH, and plasma methemoglobin levels and preserved RBC-MFR activity. The VE-coated dialyzer effectively prevented RBCs from oxidative stress, although it showed a partial effect on the reduction of total ROS activity in whole blood. In conclusion, intravenous VC plus a VE-coated dialyzer is effective in palliating HD-evoked oxidative stress, as indicated by hemolysis and lipid peroxidation, and by overexpression of proinflammation cytokines in HD patients. Using VE-coated dialyzer per se is, however, effective in reducing lipid peroxidation and oxidative damage to RBCs.

Effect of antioxidant vitamin treatment on the time course of hematological and hemorheological alterations after an exhausting exercise episode in human subjects

This study examined the effects of a 2-mo antioxidant vitamin treatment on acute hematological and hemorheological alterations induced by exhausting exercise; both sedentary and trained individuals were employed. Eighteen young male, human subjects (9 sedentary, 9 trained by regular exercise) participated in the study and performed an initial maximal aerobic cycle ergometer exercise with frequent blood sampling over a 24-h period and analysis of hematological and hemorheological parameters. All subjects were treated with an antioxidant vitamin A, C, and E regimen, supplemented orally for 2 mo, and then subjected to a second exercise test and blood sampling at the end of this period. In the sedentary group during the first testing period (before vitamin treatment), white blood cell counts and granulocyte percentages were increased at 2 h after the exercise test and remained elevated for 4-12 h. Red blood cell (RBC) deformability and aggregation were also altered by exercise in the sedentary group before vitamin treatment. However, none of these parameters in the sedentary group were altered by exercise after the 2-mo period of antioxidant vitamin treatment. With the exception of a transient rise in granulocyte percentage, these parameters were also not affected in the trained subjects before the vitamin treatment. Significant increases of RBC lipid peroxidation observed 12 h after the exercise test in both sedentary and trained subjects were also totally prevented by vitamin treatment. Our results indicate that antioxidant vitamin treatment is effective in preventing the inflammation-like response and coincident adverse hemorheological changes after an episode of exhausting exercise, and suggest that such changes may be related to exercise-induced death events.

Evaluation of lipid peroxidation in red blood cells by monitoring the uptake of sucrose and phenol red

Red blood cells (RBCs) are prone to lipid peroxidation by virtue of their function as oxygen carriers, and also because of their lipid composition. Malondialdehyde (MDA) content using thiobarbituric reagent is widely used to quantify lipid peroxidation. In this study we compare MDA assay with a newly developed assay that evaluates the uptake of sucrose and phenol red into RBCs under peroxidative stress. Both sucrose and phenol red uptake show significantly higher correlation with incubation time compared with MDA assay. Furthermore, phenol red uptake into RBCs on treatment with H(2)O(2) has a direct linear proportional relationship, whereas it is hyperbolic with MDA. The assay also clearly shows that uptake of sucrose or phenol red is specific for intact cells (RBCs) prior to hemolysis. Assay validation is carried out by using known lipid peroxidation-causing agents, such as ferrous ions, and also by using peroxidation inhibitors such as alpha-tocopherol. This new method can be applied efficiently to evaluate lipid peroxidation in RBCs as well as other cells and tissues.

Inhibition of lipid peroxidation, protein glycation and elevation of membrane ion pump activity by taurine in RBC exposed to high glucose

Background: Supplementation of taurine, a sulfur containing amino acid has been found to be beneficial in counteracting oxidative stress and in preventing experimental diabetic neuropathy, nephropathy and retinopathy. Taurine has its own capacity to prevent the suppression of membrane-bound Na +/K +ATPase activity and prevent Ca 2+ overload. This study was undertaken to test whether taurine can reduce lipid peroxidation and glycosylation and can increase the Na +/K +- and Ca 2+-ATPase activities in high glucose-treated red blood cells (RBC). Methods: Washed normal human RBC were incubated in phosphate-buffered saline with normal (6 mmol/l) or high glucose concentrations (45 mmol/l), with and without 50–150 μmol/l taurine in a shaking water bath at 37 °C for 24 h. Lipid peroxidation, glycated hemoglobin, glucose utilization and Na +/K +- and Ca 2+-ATPase activities were determined in the glucose-treated human RBC. Results: Taurine significantly lowered the level of glycated hemoglobin (GHb) and lipid peroxidation in RBC exposed to high glucose concentrations. Stimulation of glucose utilization by RBC was significant in the presence of taurine both in normal and high glucose-treated RBC. The activities of Na +/K +- and Ca 2+-ATPases in RBC membranes were significantly lowered in high glucose-treated RBC. Taurine treatment significantly prevented the reduction in activities of Na +/K +- and Ca 2+-ATPases activities in high glucose-treated RBC. Conclusions: The results show that taurine is important for the physiological functions of RBCs and the effects of taurine on glucose-treated RBC may have potential therapeutic relevance in diabetes.

Dietary (n-3) Fat and Cholesterol Alter Tissue Antioxidant Enzymes and Susceptibility to Oxidation in SHR and WKY Rats

Previously, 8% fish oil blend diets, compared to butter and soybean oil blend diets, reduced specific antioxidant enzyme activities and tissue susceptibility to in vitro oxidative stress in spontaneously hypertensive (SHR) and Wistar Kyoto (WKY) rats. Moreover, high cholesterol (5.0 g/kg diet) diets protected against in vitro tissue lipid oxidation. In this study, we hypothesized that 160 g fat/kg diet as blends of (n-6) or (n-3) oils and cholesterol would alter antioxidant enzyme activities and thus increase tissue susceptibility to oxidation. The effects of diet blends of saturated (butter, B), (n-6) (soybean oil, SBO) or (n-3) (menhaden oil, MO) oils with cholesterol (0.5 or 5.0 g/kg) on systolic blood pressure (SBP), plasma lipids, antioxidant enzymes and susceptibility to oxidation were examined in SHR and WKY rats. SBP at 13 wk of age was greater (P < 0.001) in SHR than in WKY rats, but was not affected by diets. Plasma cholesterol and triacylglycerols were decreased (P < 0.001) by MO diets. Hepatic glutathione reductase activities were reduced (P < 0.001) in SBO-fed SHR and enhanced in SBO- and MO-fed WKY rats. Glutathione levels were reduced (P < 0.001) in RBC and enhanced (P < 0.001) in livers of MO-fed rats. Lipid oxidation was enhanced (P < 0.001) in red blood cells (RBC) from SBO groups, and hearts and livers of MO groups. High cholesterol diets reduced (P < or = 0.001) susceptibility to lipid peroxidation in RBC and liver of SHR and WKY rats. Greater amounts of dietary (n-3) fat enhance tissue susceptibility to oxidation, which can be modulated by increased dietary cholesterol in SHR and WKY rats.

Contribution of haemoglobin and membrane constituents modification to human erythrocyte damage promoted by peroxyl radicals of different charge and hydrophobicity

We have investigated the influence of the free radical initiator characteristics on red blood cell lipid peroxidation, membrane protein modification, and haemoglobin oxidation. 2,2′-Azobis(2-amidinopropane) (AAPH) and 4,4′-azobis(4-cyanovaleric acid) (ACV) were employed as free radical sources. Both azo-compounds are water-soluble, although ACV presents a lowed hydrophilicity, as evaluated from octanol/water partition constants. At physiological pH, they are a di-cation and a di-anion, respectively.AAPH and ACV readily oxidise purified oxyhemoglobin in a very efficient free radical-mediated process, particularly for ACV-derived radicals, where nearly one heme moiety was modified per radical introduced into the system, suggesting that negatively charged radicals react preferentially at the heme group. The radicals derived from both azo-compounds lead to different oxidation products. Methemoglobin, hemichromes and choleglobin were produced in AAPH-promoted hemoglobin oxidation, while ACV-derived radicals predominantly form hemichromes, with very low production of choleglobin.Red cell damage was evaluated at the level of hemoglobin and membrane constituents modification, and was expressed in terms of free radical doses. Before the onset of the lytic process, ACV leads to more lipid peroxidation than AAPH, and induces a moderate oxidation of intracellular Hb. This intracellular oxidation is markedly increased if ACV hydrophilicity is decreased by lowering the pH. On the other hand, AAPH-derived radicals are considerable more efficient in promoting protein band 3 modification and cell lysis, without significant intracellular hemoglobin oxidation. These results show that the lytic process is not triggered by lipid peroxidation or hemichrome formation, and suggest that membrane protein modification is the relevant factor leading to red blood cell lysis.

Lipoic acid decreases lipid peroxidation and protein glycosylation and increases (Na + + K +)- and Ca ++-ATPase activities in high glucose-treated human erythrocytes

Lipoic acid supplementation has been found to be beneficial in preventing neurovascular abnormalities in diabetic neuropathy. Insufficient (Na + + K +)-ATPase activity has been suggested as a contributing factor in the development of diabetic neuropathy. This study was undertaken to test the hypothesis that lipoic acid reduces lipid peroxidation and glycosylation and can increase the (Na + + K +)- and Ca ++-ATPase activities in high glucose-exposed red blood cells (RBC). Washed normal human RBC were treated with normal (6 mM) and high glucose concentrations (45 mM) with 0–0.2 mM lipoic acid (mixture of S and R sterioisomers) in a shaking water bath at 37°C for 24 h. There was a significant stimulation of glucose consumption by RBC in the presence of lipoic acid both in normal and high glucose-treated RBC. Lipoic acid significantly lowered the level of glycated hemoglobin (GHb) and lipid peroxidation in RBC exposed to high glucose concentrations. High glucose treatment significantly lowered the activities of (Na + + K +)- and Ca ++-ATPases of RBC membranes. Lipoic acid addition significantly blocked the reduction in activities of (Na + + K +)- and Ca ++-ATPases in high glucose- treated RBC. There were no differences in lipid peroxidation, GHb and (Na + + K +)- and Ca ++-ATPase activity levels in normal glucose-treated RBC with and without lipoic acid. Thus, lipoic acid can lower lipid peroxidation and protein glycosylation, and increase (Na + + K +)- and Ca ++-ATPase activities in high-glucose exposed RBC, which provides a potential mechanism by which lipoic acid may delay or inhibit the development of neuropathy in diabetes.

Effects of swimming exercise on red blood cell rheology in trained and untrained rats.

Red blood cell (RBC) mechanical properties were investigated after swimming exercise in trained and untrained rats. A group of rats was trained for 6 wk (60 min swimming, daily), and another group was kept sedentary. Blood samples were obtained either within 5 min or 24 h after 60 min swimming in both groups. In the untrained rats, the RBC aggregation index decreased to 2.60 +/- 0.4 immediately after exercise from a control value of 6.73 +/- 0.18 (P < 0.01), whereas it increased to 13.13 +/- 0.66 after 24 h (P < 0.01). RBC transit time through 5-microm pores increased to 3.53 +/- 0.16 ms within 5 min after the exercise from a control value of 2.19 +/- 0. 07 ms (P < 0.005). A very significant enhancement (166%) in RBC lipid peroxidation was detected only after 24 h. In the trained group, the alterations in all these parameters were attenuated; there was a slight, transient impairment in RBC deformability (transit time = 2.64 +/- 0.13 ms), and lipid peroxidation was found to be unchanged. These findings suggest that training can significantly limit the hemorheological alterations related to a given bout of exercise. Whether this effect is secondary to the training-induced reduction in the degree of metabolic and/or hormonal perturbation remains to be determined.

Prevention of H2O2‐induced red blood cell lipid peroxidation and hemolysis by aqueous extracted turmeric

The protective effect of the aqueous extracted turmeric antioxidant protein on H2O2-induced red blood cell lipid peroxidation and hemolysis was investigated. Turmeric antioxidant protein inhibited lipid peroxidation and hemolysis by 70% and 80%, respectively, and was found to be more effective as an antioxidant than were -tocopherol and curcumin.

Photolysis and membrane lipid peroxidation of human erythrocytes by m-chloroperbenzoic acid

The aim of the present work was to investigate the biological hazard of photooxidation products of m-chloroperbenzoic acid (mCPBA), as a novel photo-sensitizer, on lysis and membrane lipid peroxidation of human red blood cells (RBC). The photohemolysis activity of mCPBA oxidative products was concentration- and exposure time-dependent. Ten minutes photoexposure time and 100 μmol/L of mCPBA concentration were optimum to study the effect of generated superoxide (O 2 •−) and hydroxyl ( •OH) radicals on RBC. The hemolytic effect of mCPBA was highly significantly inhibited by formate (as an •OH radical scavenger) compared with the partial inhibition effect of SOD-like Cu(II) complex (as O 2 •− radical Scavenger). The MDA value (an end product of membrane lipid peroxidation of RBC) induced by mCPBA was highly significantly decreased by formate. The generation of O 2 •− radicals by mCPBA was also confirmed by the partial hemolytic effect of phenazine methosulfate (PMS., O 2 •− radical generation). The data suggest the molecular mechanism of the oxygen radical species (O 2 •− and •OH through the photosensitization reaction of mCPBA and explain that hydroxyl radicals ( •OH) play an active role in the photohemolysis process and peroxidation of membrane lipids of human erythrocytes.

Aβ25–35 induces rapid lysis of red blood cells: contrast with Aβ1–42 and examination of underlying mechanisms

Amyloid β-peptide (Aβ) is produced by many different cell types and circulates in blood and cerebrospinal fluid in a soluble form. In Alzheimer's disease (AD), Aβ forms insoluble fibrillar aggregates that accumulate in association with cells of the brain parenchyma and vasculature. Both full-length Aβ (Aβ1–40/42) and the Aβ25–35 fragment can damage and kill neurons by a mechanism that may involve oxidative stress and disruption of calcium homeostasis. Circulating blood cells are exposed to soluble Aβ1–40/42 and may also be exposed to Aβ aggregates associated with the luminal surfaces of cerebral microvessels. We therefore examined the effects of Aβ25–35 and Aβ1–42 on human red blood cells (RBCs) and report that Aβ25–35, in contrast to Aβ1–42, induces rapid (10–60 min) lysis of RBCs. The mechanism of RBC lysis by Aβ25–35 involved ion channel formation and calcium influx, but did not involve oxidative stress because antioxidants did not prevent cell lysis. In contrast, Aβ1–42 induced a delayed (4–24 h) damage to RBCs which was attenuated by antioxidants. The damaging effects of both Aβ25–35 and Aβ1–42 towards RBCs were completely prevented by Congo red indicating a requirement for peptide fibril formation. Aβ1–42 induced membrane lipid peroxidation in RBC, and basal levels of lipid peroxidation in RBCs from AD patients were significantly greater than in age-matched controls, suggesting a possible role for Aβ1–42 in previously reported alterations in RBCs from AD patients.