Red cell vitamin E and oxidative damage: a dual role of reducing agents

Vitamin E deficiency in childhood: a narrative review

Vitamin E is an important nutrient from the earliest stages of life. It plays key roles as an antioxidant and in the maintenance of the immune system, among others. Vitamin E deficiency (VED), which occurs more frequently in children, is rarely addressed in the literature. This narrative review aims to summarise the chemistry, biology, serum indicators and clinical trials that have evaluated the impact of fortification and other relevant aspects of vitamin E, in addition to the prevalence of its deficiency, in children worldwide. Vitamin E intake in recommended amounts is essential for this nutrient to perform its functions in the body. Serum α-tocopherol is the most widely used biochemical indicator to assess the prevalence of VED. VED has been associated with symptoms secondary to fat malabsorption and may lead to peripheral neuropathy and increased erythrocyte haemolysis. Reduced concentrations of α-tocopherol may be caused by the combination of diets with low amounts of vitamin E and inadequate consumption of fats, proteins and calories. The lowest prevalence of VED was found in Asia and the highest in North America and Brazil. High proportions of VED provide evidence that this nutritional deficiency is a public health problem in children and still little addressed in the international scientific literature. The planning, evaluation and implementation of health policies aimed at combatting VED in the paediatric population are extremely important.

Effect of acute thermal injury in status of serum vitamins, inflammatory markers, and oxidative stress markers: preliminary data

The objective of this study was to evaluate the vitamin status, inflammatory markers, and oxidative stress markers in adult patients up to 3 days after thermal injury. This prospective study was conducted with 11 patients 24 to 72 hours after thermal injury (Burn Group), total surface area ranging from 10 to 41%, 34.3 ± 9.3 years, 82% of males, body mass index of 22.3 ± 2.9 kg/m(2). We included 11 healthy adults (Control Group), 36.5 ± 7.6 years, 73% of males, and body mass index of 23.8 ± 2.5 kg/m(2). Laboratory data were measured (plasma total protein, albumin, transferrin, lymphocyte counts, zinc, and iron), as well as serum vitamins (folic acid, vitamin B12, and vitamins A, C, and E), inflammatory stress markers (C-reactive protein, ferritin, and acid α1-glycoprotein) and oxidative stress markers such as glutathione peroxidase (GPx) and thiobarbituric acid reactive substances. The inflammatory stress was characterized by lower levels of total protein (median difference 1.2 g/dL, 95% CI: 0.4-2.1) and albumin (median difference 0.9 g/dL, 95% CI: 0.5-1.5), and higher levels of C-reactive protein (median difference -8.12 mg/dL, 95% CI: -11.62 to 4.61) and α-1 glycoprotein acid (median difference -28.56 mg/dL, 95% CI: -51.57 to -5.07) in burn patients. Decreased serum levels of vitamin A (median difference 1.10 μmol/L, 95% confidence interval [CI]: 0.42-1.66) and vitamin C (median difference 0.82 mg/dL, 95% CI: 0.50-1.04) were also detected. There was no statistical evidence of difference in the serum levels of glutathione peroxidase and thiobarbituric acid reactive substances between burn patients and controls, respectively. Even though there is an inflammatory stress, the obtained data showed that oxidative stress markers are normal 24 to 72 hours after burn injury. The decrease in negative acute phase protein may account for the diminished serum levels of vitamin A, which seems to be related to inflammatory stress. The marked decrease in the serum levels of vitamin C can be justified by augmented cutaneous loss and consumption in the regeneration of vitamin E.

Curbing inflammation in burn patients

Patients who suffer from severe burns develop metabolic imbalances and systemic inflammatory response syndrome (SIRS) which can result in multiple organ failure and death. Research aimed at reducing the inflammatory process has yielded new insight into burn injury therapies. In this review, we discuss strategies used to curb inflammation in burn injuries and note that further studies with high quality evidence are necessary.

Serum vitamin E concentration and osmotic fragility in female long-distance runners

The objective of this study was to assess the nutritional adequacy of sub-elite runners with irregular menstrual function (n=10) and that of a comparable group of runners with regular menstrual function (n=10), with a special focus on vitamin E. Based on 3 days' records of weighed dietary intake, the mean energy intakes of micro- and macronutrients were estimated. Both estimated daily energy intake (irregular: 9.9+/-0.4 MJ; regular: 12.2+/-0.7 MJ; mean+/-sx) and intake of dietary fat (irregular: 61+/-6 g; regular: 98+/-12 g) were lower in athletes with irregular menstrual function than in athletes with regular menstrual function (P=0.01). Estimated intake of vitamin E was below recommended values in both groups. Serum concentrations of alpha-tocopherol were used to evaluate vitamin E status, which were normal in athletes with regular menstrual function (27.3+/-3.6 micromol.l(-1)) but below normal values in athletes with irregular menstrual function (15.7+/-0.8 micromol.l(-1); P=0.01). Furthermore, post-exercise osmotic fragility in red blood cells was inversely related to resting alpha-tocopherol concentrations. Our results indicate that irregular menstrual function in athletes on a low-fat diet is associated with low concentrations of circulating alpha-tocopherol, rendering the red blood cells more susceptible to haemolysis in connection with physical activity.

Dose-dependent modulation of systemic lipid peroxidation and activity of anti-oxidant enzymes by vitamin E in the rat

The objective of this work was to examine the time-dependent pro-oxidant versus antioxidant effect of various doses of vitamin E used commonly in experimental studies. Erythrocyte activity of superoxide dismutase (SOD), glutathione peroxidase (GPX), catalase (CAT) and plasma lipid peroxidation levels were investigated following biweekly intramuscular administration of 100, 300 and 600 mg/kg of vitamin E at a baseline time point, and additionally at 2, 4 and 6 weeks after initiating treatment. Vitamin E had an antioxidant effect when administered at low doses over short time periods, and increased the activity of antioxidant enzymes. At higher doses and over longer time periods, it increased the level of lipid peroxidation, and attenuated the activity of antioxidant enzymes. These results suggest that time-dependent variations in vitamin E effects should be considered in design and interpretation of experimental antioxidant studies, as well as during clinical trials.

n-6 and n-3 fatty acids ratio and vitamin E in porcine maternal diet influence the antioxidant status and immune cell eicosanoid response in the progeny

Five groups of lactating sows were fed diets containing 8% of either added rapeseed oil, fish oil or sunflower oil and 60 mg vitamin E/kg feed, or the diets with sunflower oil and fish oil, respectively, supplemented with 500 mg vitamin E/kg. Supplementation of vitamin E to the sows increased the concentration of alpha-tocopherol of the muscle, and addition of sunflower oil decreased the activity of glutathione peroxidase in liver cytosol compared to fish oil and rapeseed oil. The composition of fatty acids of alveolar macrophages (AM) of piglets was influenced by the dietary fat sources provided the sows, i.e., the ratio of n-6:n-3 fatty acids was highest in AM of piglets suckling sows of the sunflower oil treatments, and lowest in AM of piglets suckling sows fed fish oil with the rapeseed oil treatment in between. The ex vivo synthesis of prostaglandin E(2) and thromboxane B(2) in AM of piglets suckling sows fed sunflower oil was elevated compared to piglets suckling sows fed fish oil. Vitamin E supplementation to sows enhanced the synthesis of these eicosanoids, and also the concentration of alpha-tocopherol in the AM of the piglets.

Redox imbalance, macrocytosis, and RBC homeostasis

The erythrocyte represents a major component of the antioxidant capacity of the blood through the enzymes contained in the cell, the glutathione system, and the low-molecular-weight antioxidants of the erythrocyte membrane. A further major red blood cell contribution is in regenerating consumed redox equivalents via the oxidative pentose phosphate pathway and glutathione reductase. Moreover, its extracellular antioxidant capacity, its mobility, and the existence of reducing equivalents far in excess of its normal requirements make erythrocytes function as an effective oxidative sink in the organism. That is why red blood cell metabolism and homeostasis strongly affect the antioxidant properties of the whole body. Conversely, the relation between macrocytosis and oxidative stress has not been fully delineated. Reviewing the mechanisms involved in red blood cell homeostasis in cases of redox imbalance is crucial in identification of factors that could potentially improve erythrocyte survival and defense against oxidant damage.

Genistein abrogates pre-hemolytic and oxidative stress damage induced by 2,2′-Azobis (Amidinopropane)

The pre-hemolytic mechanism induced by free radicals initiated from water-soluble 2,2'-azobis (2-amidinopropane) hydrochloride (AAPH) and its reversal by genistein was investigated in human erythrocytes. The time course of K+ efflux compared to the occurrence of hemolysis suggests that AAPH-induced hemolysis occurs indirectly via pore formation and band 3 oxidation as expected. However, genistein inhibited hemolysis, LDH release and membrane protein oxidation but not K+ efflux. This indicated that erythrocyte protein oxidation possibly in the hydrophobic core plays a significant role in the membrane pre-hemolytic damage. Chemiluminescence (CL) analysis carried out in non-lysed erythrocytes treated with AAPH showed a dramatic increase in CL indicating both reduced levels of antioxidants and increased membrane lipid peroxide. The V0 value was also increased up to 6 times, denoting a high degree of membrane peroxidation very early in erythrocyte membrane damage. The whole process was inhibited by genistein in a dose-dependent manner. These results indicate that the genistein inhibited both hemolysis and pre-hemolytic damage and also hindered membrane lipid peroxide formation and protein oxidation. In addition, it is suggested that pre-hemolytic damage is mediated mainly by the oxidation of both phospholipid and protein located in the deeper hydrophobic region of the membrane.

Endotoxin increases hepatic susceptibility to lipid peroxidation: A possible role of iron

The purpose of this study was to investigate the possible mechanism by which endotoxin enhances peroxidative damage to membrane lipids. Male B6C3 mice were treated with endotoxin intraperitoneally 0 or 20 mg/kg body weight for 24 h. Freshly prepared liver homogenate was incubated with either 1-5 mM of reduced glutathione (GSH), glucose, H(2)O(2), ascorbic acid (AA), FeSO(4), FeCl(3), EDTA, FeCl(3) plus AA, AA plus EDTA or EDTA plus FeCl(3) in phosphate-buffered saline (PBS), pH 7.0, or PBS, at 37 degrees C for 60 min. The levels of lipid peroxidation products, thiobarbituric acid reactants (TBAR), were significantly higher in the liver of endotoxin-treated mice, and the values were markedly increased following incubation. Compared to PBS, incubation with H(2)O(2), FeCl(3), FeSO(4), and AA, but not glucose, significantly enhanced TBAR formation. The greatest increase of TBAR was found when AA and FeCl(3) were added together. On the other hand, EDTA and GSH inhibited the formation of TBAR during incubation. When added before AA, EDTA completely inhibited the peroxidative effect of AA or FeSO4, and when added subsequent to AA, EDTA partially prevented the adverse effect of AA. The results obtained suggest that ionic iron plays an important role in initiating endotoxin-induced peroxidative damage to membrane lipids, and that AA may be involved in releasing iron from its protein complex and/or maintaining ionic iron in a reduced or catalytic state.

Dual effect of glucose on LDL oxidation: dependence on vitamin E

The aim of the present study was to determine the direct effect of glucose on LDL oxidation, a key step in the development of atherosclerosis. Purified human LDL were incubated with glucose (500 mg/dl) and LDL oxidation was started by adding CuCl(2) to the media. Glucose delayed the vitamin E consumption, but accelerated the formation of conjugated dienes and increased both the formation of thiobarbituric acid reacting substances (TBARS) and LDL electrophoretic mobility. When LDL were incubated with increasing concentrations of glucose and submitted to oxidation, the formation of conjugated dienes, TBARS, and the electrophoretic mobility increased in a concentration-dependent manner. When LDL was enriched with vitamin E, it showed a delay in the formation of conjugated dienes, even in the presence of glucose. To determine whether glucose had any effect on LDL oxidation, once the process was started and vitamin E consumed, LDL were submitted to oxidation and, at different times thereafter, glucose was added into the media. Under these conditions glucose also accelerated the LDL oxidation. In summary, present results show that in LDL submitted to oxidation, glucose delays the early phases of the oxidation, slowing the vitamin E consumption, but it accelerates the rate of LDL oxidation once LDL vitamin E has been consumed; the effect being concentration-dependent.

Oxidative stress during ex vivo hemodialysis of blood is decreased by a novel hemolipodialysis procedure utilizing antioxidants

The high cardiovascular mortality in patients receiving hemodialysis (HD) has been attributed, in part, to oxidative stress. Here we examined the effectiveness of antioxidants introduced by means of a novel hemolipodialysis (HLD) procedure in terms of reducing oxidative stress during ex vivo blood circulation. Oxidative stress was studied in a model HD system resembling the extracorporeal circulation of blood during clinical HD. Blood circulation produced an increase of up to 280% in free hemoglobin levels and an increase of 320% in electronegative LDL (LDL(-)) subfraction. A significant correlation between LDL(-) and free hemoglobin levels confirmed previous findings that LDL(-) formation during ex vivo circulation of blood can be mediated by the oxidative activity of free hemoglobin. These effects were significantly attenuated during HLD using a dialysis circuit containing vitamin E with or without vitamin C. By contrast, HLD with vitamin C alone had a marked pro-oxidant effect. TBARS, lipid hydroperoxides, vitamin E and beta-carotene content in LDL were not significantly altered by the HD procedure. These findings demonstrate the occurrence of oxidative stress in human plasma where lipoproteins are a target and indicate antioxidant-HLD treatment as a specific new approach to decreasing the adverse oxidative stress frequently associated with cardiovascular complications in high-risk populations of uremic patients.

Long-term pharmacologic doses of vitamin E only moderately affect the erythrocytes of patients with type 1 diabetes mellitus

In erythrocytes from diabetic patients, increased membrane lipid peroxidation might lead to abnormalities in composition and function. To study this relationship, we investigated the effects of a moderate pharmacologic dose of vitamin E for 1 y on erythrocyte membrane peroxidation in vitro and on its fatty acid composition, antioxidant capacity and rheological function. In a random and double-blind manner, type 1 diabetic patients (n = 44) were assigned to the following two groups: Group S received 250 IU (168 mg) d-alpha tocopherol 3 times daily for 1 y. Group P received placebo for 6 mo followed by d-alpha-tocopherol for an additional 6 mo. Variables were monitored every 3 mo. After 3 mo of supplementation, serum vitamin E doubled (P < 0.0005), thiobarbituric acid reactive substances in erythrocyte membranes incubated with tert-butyl hydroperoxide decreased by 25% (P = 0.006) and the lagtime of fluorescence increased from 28 +/- 16 to 41 +/- 28 min (P = 0.028). Patients who did not respond to supplementation (13 of 44) had lower serum lipids (P = 0.017) and body mass index (P = 0.024). We did not detect any significant effects of vitamin E supplementation on membrane lipid composition, antioxidant capacity or blood viscosity. Continuing supplementation for up to 1 y did not further affect serum vitamin E or membrane peroxidation. Stopping supplementation was followed by a return to inclusion values. These results show that the decrease in erythrocyte membrane peroxidation after vitamin E supplementation is moderate, saturable, reversible, restricted to some individuals and has no detectable effect on erythrocyte composition and function.

Glutathione (GSH) and the toxicity of oxidised low-density lipoprotein to human monocyte-macrophages

Macrophage death, believed to be an important event in the pathogenesis of human atherosclerosis, can be induced by oxidised low-density lipoprotein (LDL) in vitro. Supplementation of the culture medium with 5 mM GSH significantly protected human monocyte-macrophages in vitro against the toxicity of copper-oxidised LDL. Oxidation products of LDL include the aldehyde 4-hydroxynonenal (HNE). We present evidence that conjugation of HNE by GSH contributes to this protection. In the absence of cells, HPLC analysis showed there were marked reductions in the levels of both pure HNE and HNE in copper-oxidised LDL in the presence of GSH. However, GSH did not reverse protein modification, as judged by agarose gel electrophoresis, nor did it influence the depletion of polyunsaturated fatty acids, which were assessed using gas chromatography. The possible implications for human atherosclerosis are discussed.

Vitamin E and C in the prevention of metal nephrotoxicity in developing rats

The protective effect of vitamin E and C on sodium chromate (Cr) and thallium (Tl) induced nephrotoxicity was tested in 10- and 55-day-old rats. The concentrations of Cr and Tl were determined in renal cortex and medulla by atomic absorption spectrometry. Urinary volume and protein excretion as well as blood urea nitrogen (BUN) concentration were determined as parameters of nephrotoxicity. Cr and Tl induced nephrotoxicity was significantly more expressed in adult than in young rats. In Cr and Tl nephrotoxicity the protective effect of vitamin E was evident in both age groups. Vitamin E decreased Tl concentration in renal tissue. Therefore its protective effect is not to be attributed to its known antioxidant effect but to lower Tl concentration in renal tissue. Vitamin C was protective in Cr and Tl induced nephrotoxicity in adult rats without influence on metal concentrations in renal tissue. The dose necessary for protection against toxic Cr action in adult rats was not tolerated by young rats. The combined administration of both vitamins abolished the protective effect against Cr nephrotoxicity of the administration of each vitamin alone in adult rats. When vitamin E and C were administered in Tl treated adult and young rats the protective effect was the same as after the administration of each vitamin alone. Possible mechanisms are discussed.

Vitamins E plus C and interacting conutrients required for optimal health. A critical and constructive review of epidemiology and supplementation data regarding cardiovascular disease and cancer

Antioxidants are crucial components of fruit/vegetable rich diets preventing cardiovascular disease (CVD) and cancer: plasma vitamins C, E, carotenoids from diet correlate prevalence of CVD and cancer inversely, low levels predict an increased risk of individuals which is potentiated by combined inadequacy (e.g., vitamins C + E, C + carotene, A + carotene); self-prescribed rectification of vitamins C and E at adequacy of other micronutrients reduce forthcoming CVD, of vitamins A, C, E, carotene and conutrients also cancer; randomized exclusive supplementation of beta-carotene +/- vitamin A or E lack benefits except prostate cancer reduction by vitamin E, and overall cancer reduction by selenium; randomized intervention with synchronous rectification of vitamins A + C + E + B + minerals reduces CVD and counteracts precancerous lesions; high vitamin E supplements reveal potentials in secondary CVD prevention. Plasma values desirable for primary prevention: > or = 30 mumol/l lipid-standardized vitamin E (alpha-tocopherol/cholesterol > or = 5.0 mumol/mmol); > or = 50 mumol/l vitamin C aiming at vitamin C/vitamin E ratio > 1.3-1.5; > or = 0.4 mumol/l beta- (> or = 0.5 mumol/l alpha+ beta-) carotene.

CONCLUSIONS

In CVD vitamin E acts as first risk discriminator, vitamin C as second one; optimal health requires synchronously optimized vitamins C + E, A, carotenoids and vegetable conutrients.

Abeta25-35 induces rapid lysis of red blood cells: contrast with Abeta1-42 and examination of underlying mechanisms

Amyloid beta-peptide (A beta) is produced by many different cell types and circulates in blood and cerebrospinal fluid in a soluble form. In Alzheimer's disease (AD), A beta forms insoluble fibrillar aggregates that accumulate in association with cells of the brain parenchyma and vasculature. Both full-length A beta (A beta1-40/42) and the A beta25-35 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 A beta1-40/42 and may also be exposed to A beta aggregates associated with the luminal surfaces of cerebral microvessels. We therefore examined the effects of A beta25-35 and A beta1-42 on human red blood cells (RBCs) and report that A beta25-35, in contrast to A beta1-42, induces rapid (10-60 min) lysis of RBCs. The mechanism of RBC lysis by A beta25-35 involved ion channel formation and calcium influx, but did not involve oxidative stress because antioxidants did not prevent cell lysis. In contrast, A beta1-42 induced a delayed (4-24 h) damage to RBCs which was attenuated by antioxidants. The damaging effects of both A beta25-35 and A beta1-42 towards RBCs were completely prevented by Congo red indicating a requirement for peptide fibril formation. A beta1-42 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 A beta1-42 in previously reported alterations in RBCs from AD patients.