Effect of vitamin E on hydrogen peroxide production by human vascular endothelial cells after hypoxia/reoxygenation

Three new triterpenoids isolated from the aerial parts of Ilex cornuta and protective effects against H2O2-induced myocardial cell injury

In the present study, three new triterpenoids, 23-hydroxyurs-12, 18-dien-28-oic acid 3β-O-α-L-arabinopyranoside (1), 23-hydroxyurs-12, 18-dien-28-oic acid 3β-O-β-D-glucuronopyranoside-6-O-methyl ester (2), and urs-12, 18-dien-28-oic acid 3β-O-β-D-glucuronopyranoside-6-O-methyl ester (3), and a known triterpenoid, 3β-hydroxy-urs-2, 18-dien-28-oic acid (4, randialic acid B), were isolated from the aerial parts of Ilex cornuta. Their structures were identified by the spectroscopic analyses (IR, ESI-MS, HR-ESI-MS, and 1D and 2D NMR) and chemical reactions. Compound 4 showed significant cell-protective effects against H₂O₂-induced H9c2 cardiomyocyte injury. Compounds 1-4 did not show any significant DPPH radical scavenging activity.

Martian Superoxide and Peroxide O2 Release (OR) Assay: A New Technology for Terrestrial and Planetary Applications

This study presents an assay for the detection and quantification of soil metal superoxides and peroxides in regolith and soil. The O2 release (OR) assay is based on the enzymatic conversion of the hydrolysis products of metal oxides to O2 and their quantification by an O2 electrode based on the stoichiometry of the involved reactions. The intermediate product O₂˙⁻ from the hydrolysis of metal superoxides is converted by cytochrome c to O2 and by superoxide dismutase (SOD) to ½ mol O2 and ½ mol H2O2, which is then converted by catalase (CAT) to ½ mol O2. The product H2O2 from the hydrolysis of metal peroxides and hydroperoxides is converted to ½ mol O2 by CAT. The assay method was validated in a sealed sample chamber by using a liquid-phase Clark-type O2 electrode with known concentrations of O₂˙⁻ and H2O2, and commercial metal superoxide and peroxide mixed with Mars analog Mojave and Atacama Desert soils. Carbonates and perchlorates, both present on Mars, do not interfere with the assay. The assay lower limit of detection, when using luminescence quenching/optical sensing O2-electrodes, is 1 nmol O2 cm(-3) or better. The activity of the assay enzymes SOD and cytochrome c was unaffected up to 6 Gy exposure by γ radiation, while CAT retained 100% and 40% of its activity at 3 and 6 Gy, respectively, which demonstrates the suitability of these enzymes for planetary missions, for example, on Mars or Europa.

Identification of schisandrin as a vascular endothelium protective component in YiQiFuMai Powder Injection using HUVECs binding and HPLC-DAD-Q-TOF-MS/MS analysis

YiQiFuMai Powder Injection (YQFM) is a re-developed preparation based on the well-known traditional Chinese medicine formula Sheng-mai-san. It has been widely used for the treatment of cardiovascular disease with definite clinical efficacy in China, but its bioactive molecules remain obscure. In this study, an effective method has been employed as a tool for screening active components in YQFM, using human umbilical vein endothelial cells (HUVECs) extraction and liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (Q-TOF MS/MS). Nine compounds, which could interact with HUVECs, were identified as ginsenosides Rb1, Rc, Rb2, Rd, 20(S)-Rg3, 20(R)-Rg3, Rk1/Rg5 and schisandrin by comparing with reference substances or literature. In vitro assays showed that schisandrin at concentrations of 10-100 μM protected HUVECs from hypoxia/reoxygenation (H/R) injury, increased cell viability, nitric oxide (NO) content and decreased lactate dehydrogenase (LDH) leakage, malonaldehyde (MDA) content and ROS generation. Moreover, schisandrin pretreatment inhibited cell apoptosis, as evidenced by inhibiting activation of caspase-3 and increasing the Bcl-2/Bax ratio. These data indicate that HUVECs biospecific extraction coupled with HPLC-ESI-Q-TOF-MS/MS analysis is a reliable method for screening potential bioactive components from traditional Chinese medicines. Meanwhile, the vascular endothelium protective property of schisandrin might be beneficial for the treatment of cardiovascular disease.

Restoration of tryptophan hydroxylase functions and serotonin content in the Atlantic croaker hypothalamus by antioxidant treatment during hypoxic stress

Antioxidants are prototypical scavengers of oxygen-free radicals and have been shown to prevent neuroendocrine dysfunction in vertebrates during oxidative stress. In the present study, we investigated whether antioxidant treatment can reverse hypoxia-induced down-regulation of hypothalamic tryptophan hydroxylase (TPH) and serotonergic functions in Atlantic croaker. Hypothalamic neuronal contents of TPH-1 and TPH-2 proteins, serotonin (5-hydroxytryptamine, 5-HT) and its precursor, 5-hydroxytryptophan (5-HTP) as well as hypothalamic TPH-1 and TPH-2 mRNA expression and TPH activity were measured in croaker after exposure to hypoxia and treatment with pharmacological agents. Multiple injections of N-ethylmaleimide, a sulfhydryl alkylating agent, caused comparable decreases in hypothalamic TPHs functions and 5-HT contents to that induced by hypoxia exposure (dissolved oxygen: 1.7 mg/L for 4 weeks) which were partially restored by repeated injections with a nitric oxide synthase (NOS)-inhibitor and/or vitamin E. Double-labeled immunohistochemical results showed that TPHs and 5-HT neurons were co-expressed with neuronal NOS (nNOS, a neuroenzyme) that catalyzes the production of nitric oxide, a free radical, in hypothalamic neurons. These results suggest that hypoxia-induced impairment of TPH and serotonergic functions are mediated by nNOS and involve the generation of free radicals and a decrease in the antioxidant status. This study provides, to our knowledge, the first evidence of a protective role for an antioxidant in maintaining neural TPHs functions and 5-HT regulation in an aquatic vertebrate during hypoxic stress.

Method for the simultaneous determination of free/protein malondialdehyde and lipid/protein hydroperoxides

A simple and sensitive method is presented for the simultaneous quantification (spectrophotometric and spectrofluorimetric) of the main lipid and protein peroxidation products after their initial fractionation: free malondialdehyde (FrMDA), protein-bound malondialdehyde (PrMDA), total hydroperoxides (LOOH), and protein hydroperoxides (PrOOH). FrMDA and PrMDA (released from proteins by alkaline hydrolysis) are measured after the reaction of MDA with thiobarbituric acid (TBA) under acidic conditions, by the specific fluorimetric quantification of the resulting MDA-(TBA)2 adduct chromophore. The measurement of LOOH and PrOOH is based on the reaction of Fe(3+) (resulting from the reaction of LOOH and PrOOH with Fe(2+)) with xylenol orange (XO) and the photometric quantification of the resulting XO-Fe complex. The sensitivity of the assays for FrMDA/PrMDA and LOOH/PrOOH is 20 and 100pmol, respectively. The method was applied successfully on human plasma and can be used for the evaluation of oxidative stress in both basic and clinical research.

Bicarbonate modulates oxidative and functional damage in ischemia-reperfusion

The carbon dioxide/bicarbonate (CO(2)/HCO(3)(-)) pair is the main biological pH buffer. However, its influence on biological processes, and in particular redox processes, is still poorly explored. Here we study the effect of CO(2)/HCO(3)(-) on ischemic injury in three distinct models (cardiac HL-1 cells, perfused rat heart, and Caenorhabditis elegans). We found that, although various concentrations of CO(2)/HCO(3)(-) do not affect function under basal conditions, ischemia-reperfusion or similar insults in the presence of higher CO(2)/HCO(3)(-) resulted in greater functional loss associated with higher oxidative damage in all models. Because the effect of CO(2)/HCO(3)(-) was observed in all models tested, we believe this buffer is an important determinant of oxidative damage after ischemia-reperfusion.

Determinants and clinical significance of plasma oxidized LDLs in older individuals. A 9 years follow-up study

Oxidized LDLs (ox.LDLs) uptake by macrophages inside the arterial wall is a crucial step in atherosclerotic disease, and some studies suggest that high ox.LDLs plasma levels might be associated with cardiovascular disease (CVD). However, whether high ox.LDLs continue to be a CVD risk factors in older persons is unknown. We investigated the clinical correlates of plasma ox.LDLs, and their role in predicting long-term CVD/cardiac mortality in 1025 older community dwelling individuals (mean age: 75.5 ± 7.4 years; females: 55%) from the InCHIANTI study. Kaplan-Meier curves were fitted to explore the relationship between tertiles of ox.LDLs (ox.LDL/LDL-C ratio) and time to CVD/cardiac death. Hazard Ratios (HR) were estimated by Cox regression analysis. At multivariate analysis, ox.LDLs were independently associated with LDL-C, triglycerides, and HDL-C (adjusted r(2): 0.42; P = 0.001). The ox.LDL/LDL-C ratio (the extent of LDLs oxidation) was independently correlated with HDL-C, triglycerides, and beta-carotene (adjusted r(2): 0.15, P = 0.001). Among 1025 individuals, 392 died after 9 years, 166 from CVD. The HR for CVD/cardiac mortality was not significantly different across tertiles of ox.LDLs or ox.LDL/LDL-C ratio, both in the whole sample and in individuals with prevalent CVD. We conclude that in an elderly population LDL-C, triglycerides, and HDL-C are the most important determinants of ox.LDLs levels, indirectly suggesting an association between small dense LDLs and LDLs oxidation. No association emerged between higher ox.LDLs levels and 9 years CVD/cardiac mortality, suggesting that in advanced age the prognostic information added by ox.LDLs on CVD/cardiac mortality might be negligible.

Effects of hypoxia exposure on hepatic cytochrome P450 1A (CYP1A) expression in Atlantic croaker: molecular mechanisms of CYP1A down-regulation

Hypoxia-inducible factor-α (HIF-α) and cytochrome P450 1A (CYP1A) are biomarkers of environmental exposure to hypoxia and organic xenobiotic chemicals that act through the aryl hydrocarbon receptor, respectively. Many aquatic environments heavily contaminated with organic chemicals, such as harbors, are also hypoxic. Recently, we and other scientists reported HIF-α genes are upregulated by hypoxia exposure in aquatic organisms, but the molecular mechanisms of hypoxia regulation of CYP1A expression have not been investigated in teleost fishes. As a first step in understanding the molecular mechanisms of hypoxia modulation of CYP1A expression in fish, we characterized CYP1A cDNA from croaker liver. Hypoxia exposure (dissolved oxygen, DO: 1.7 mg/L for 2 to 4 weeks) caused significant decreases in hepatic CYP1A mRNA and protein levels compared to CYP1A levels in fish held in normoxic conditions. In vivo studies showed that the nitric oxide (NO)-donor, S-nitroso-N-acetyl-DL-penicillamine, significantly decreased CYP1A expression in croaker livers, whereas the competitive inhibitor of NO synthase (NOS), N(ω)-nitro-L-arginine methyl ester, restored CYP1A mRNA and protein levels in hypoxia-exposed (1.7 mg DO/L for 4 weeks) fish. In vivo hypoxia exposure also markedly increased interleukin-1β (IL-1β, a cytokine), HIF-2α mRNA and endothelial NOS (eNOS) protein levels in croaker livers. Pharmacological treatment with vitamin E, an antioxidant, lowered the IL-1β, HIF-2α mRNA and eNOS protein levels in hypoxia-exposed fish and completely reversed the down-regulation of hepatic CYP1A mRNA and protein levels in response to hypoxia exposure. These results suggest that hypoxia-induced down-regulation of CYP1A is due to alterations of NO and oxidant status, and cellular IL-1β and HIF-α levels. Moreover, the present study provides the first evidence of a role for antioxidants in hepatic eNOS and IL-1β regulation in aquatic vertebrates during hypoxic stress.

Characterization of three IGFBP mRNAs in Atlantic croaker and their regulation during hypoxic stress: potential mechanisms of their upregulation by hypoxia

Insulin-like growth factor-binding proteins (IGFBPs) play important roles in downregulating IGF activity and growth and development in vertebrates under hypoxic stress. However, the mechanisms of hypoxia regulation of IGFBPs in teleost fishes are unknown. The involvement of reactive oxygen species (ROS) and hypoxia-inducible factors (HIFs) in hypoxia upregulation of IGFBPs in Atlantic croaker were investigated. Three croaker IGFBPs, IGFBP-1, IGFBP-2, and IGFBP-5, were cloned and characterized. Chronic hypoxia exposure [dissolved oxygen (DO): 1.7 mg/l for 2-4 wk] caused significant increases in hepatic and neural IGFBP-1 mRNA expression compared with tissue mRNA levels in fish held under normoxic conditions (6.5 mg DO/l). Moreover, longer-term chronic hypoxia exposure (2-2.7 mg DO/l for 15-20 wk) caused significant increases in mRNA levels of all three IGFBPs in both liver and brain tissues. Hypoxia exposure also markedly increased superoxide radical (O(2)(·-), an index of ROS) production and HIF-1α mRNA and HIF-2α protein expression in croaker livers. Pharmacological treatment with an antioxidant attenuated the hypoxia-induced increases in O(2)(·-) production and HIFα mRNA and protein expression as well as the elevation of IGFBP-1 mRNA levels. These results suggest that the upregulation of IGFBP expression under hypoxia stress is due, in part, to alterations in the antioxidant status, which may involve ROS and HIFs.

Effect of a blueberry nutritional supplement on macronutrients, food group intake, and plasma vitamin E and vitamin C in US athletes

Antioxidants from a blueberry beverage may impact plasma vitamins. We examined vitamins/food selection in 12 college athletes during 30 days compared with placebo. Blood was collected before and after exercise at the beginning of the study (day 1) and then after a 30-day period of taking a daily supplemental beverage (day 30). The six trials involved blood that was drawn pre-beverage ingestion/pre-exercise (trials 1 and 4), post-beverage ingestion/pre-exercise (trials 2 and 5), and post-beverage ingestion/1 h post-exercise (trials 3 and 6), on day 1 (trials 1, 2, and 3) and day 30 (trials 4, 5, and 6). Analysis of variance revealed non-significant differences for macronutrient or gamma-tocopherol and vitamin C intakes by food frequency questionnaire or plasma vitamins by liquid chromatography. There was a trend (P = 0.083) in the group x time interaction for alpha-tocopherol intake by repeated-measures analysis of variance. Blueberry alpha-tocopherol (23.91 +/- 9.31 mg) was significantly (P < 0.05) higher than placebo alpha-tocopherol intake (7.59 +/- 0.95 mg) on day 1, but not on day 30 (blueberry, alpha-tocopherol = 9.04 +/- 2.35 mg, placebo, alpha-tocopherol = 11.46 +/- 3.65 mg) by pairwise comparisons. Blueberry supplementation did not affect plasma vitamin concentrations or gamma-tocopherol and vitamin C intakes, and may reduce alpha-tocopherol intake in those starting with a higher alpha-tocopherol intake, yet not altering athletes' eating habits.

Isoforms of vitamin E have opposing immunoregulatory functions during inflammation by regulating leukocyte recruitment

Reports indicate contradictory outcomes for anti-inflammatory functions of the alpha-tocopherol isoform of vitamin E in clinical studies of asthma and atherosclerosis. These seemingly disparate clinical results are consistent with novel unrecognized properties of isoforms of vitamin E reported in this study. We demonstrate that the isoform d-gamma-tocopherol elevates inflammation in experimental asthma. Moreover, d-gamma-tocopherol, at as little as 10% the concentration of d-alpha-tocopherol, ablates the anti-inflammatory benefit of the d-alpha-tocopherol isoform. A mechanism for these opposing immunoregulatory functions of purified tocopherols at physiological concentrations is not through modulation of expression of several cytokines, chemokines, or adhesion molecules, but is, at least in part, by regulation of endothelial cell signals during leukocyte recruitment. These opposing regulatory functions of vitamin E isoforms have impact on interpretations of vitamin E studies. In summary, our studies with purified tocopherol isoforms alter our understanding of vitamin E regulation of vascular function and asthma.

Antioxidant activity of Antrodia camphorata on free radical-induced endothelial cell damage

AIM OF THE STUDY

Antrodia camphorata (A. camphorata) is well known in Taiwan as a traditional Chinese medicine. The purpose of this study is to evaluate the antioxidant activity of Antrodia camphorata on free radical-induced endothelial cell damage.

MATERIALS AND METHODS

In this study, a human umbilical vein endothelial cell (EC) culture system was used to evaluate the effects of the fermented culture broth of A. camphorata (FCBA) and aqueous extracts of mycelia from A. camphorata (AEMA) against the oxidative cell damage induced by the free-radical generator AAPH.

RESULTS

The present investigations show that FCBA (25-100 microg/mL) and AEMA (50-200 microg/mL) effectively protect the ECs from damage after exposure to 15 mM AAPH for 16h. However, cell viability was not affected in ECs under controlled conditions after FCBA or AEMA treatment. An increase in EC prostacyclin (PGI(2)) production in response to AAPH exposure was positively and negatively correlated with cell damage and FCBA/AEMA concentration, respectively. Both FCBA and AEMA treatment significantly inhibited AAPH-apoptotic cell death in the ECs, as evidence by reduced DNA fragmentation, cytochrome c release, caspase-3 activation, and dysregulation of Bcl-2 and Bax. Moreover, the AAPH-induced reductions in EC SOD activity and protein levels are prevented by FCBA and AEMA.

CONCLUSION

Our findings suggest that A. camphorata possesses antioxidant properties and improves endothelial function, further offering effective protection from atherosclerosis.

alpha-Tocopherol intake and plasma concentration of Hispanic and non-Hispanic white elders is associated with dietary intake pattern

alpha-Tocopherol from foods has been associated with protection against several chronic diseases and maintenance of immune function. However, most people do not meet current recommendations for intake. We examined alpha-tocopherol intake and plasma concentration in a representative sample of Puerto Rican and Dominican older adults (n = 447) and in neighborhood-matched non-Hispanic whites (n = 155). A validated food frequency questionnaire was used to assess dietary intake. Mean dietary intakes of alpha-tocopherol were 6 mg in both ethnicities. Only 4.7% of women and 7.9% of men met the estimated average requirement (12 mg/d) for vitamin E from food alone. Top sources of alpha-tocopherol for Hispanics included oils and milk, and for non-Hispanic whites they were ready-to-eat breakfast cereal and sweet baked products. Mean plasma alpha-tocopherol concentrations were 24.5 micromol/L for Hispanics and 25.8 micromol/L for non-Hispanic whites (P > 0.05). Plasma alpha-tocopherol was positively associated with alpha-tocopherol intake (P = 0.003), and significance remained after adjusting covariates and after exclusion of supplement users (P for trend = 0.008). We identified the following 5 dietary patterns by cluster analysis: 1) fruit and breakfast cereal, 2) starchy vegetables, 3) rice, 4) milk and milk products, and 5) sweets. Those following the sweets pattern had the lowest plasma alpha-tocopherol relative to those following the fruit and breakfast cereal or milk patterns (P < 0.05 for all), although they had similar intakes. A large proportion of these elders (>90%) have inadequate intake of alpha-tocopherol, and plasma concentrations were associated with intake patterns.

Lower plasma vitamin E levels are associated with the frailty syndrome: the InCHIANTI study

BACKGROUND

The primary biologic mechanism that causes frailty in older persons has never been adequately explained. According to recent views, oxidative stress may be the driving force of this condition. We tested the hypothesis that, independent of confounders, low plasma levels of vitamin E (alpha-tocopherol), the main fat-soluble human antioxidant, are associated with the frailty syndrome in older persons free from dementia and disability.

METHODS

The study sample included 827 older (> or =65 years) persons (women, 54%) who participated in a population-based epidemiological study. Frail participants were identified based on the presence of at least three of five of the following features: self-reported weight loss, low energy, slow gait speed, low grip strength, and low physical activity. Participants with none of these features were considered nonfrail, while participants with one or two were considered intermediate frail. Plasma vitamin E levels were determined using reverse-phase high-performance liquid chromatography. Measured confounders included lower extremity muscle strength, cognitive function, diseases, and factors related to vitamin E metabolism.

RESULTS

Age- and gender-adjusted levels of vitamin E decreased gradually from the nonfrail to the frail group (p for trend =.015). In the logistic model adjusted for multiple potential confounders, participants in the highest vitamin E tertile were less likely to be frail than were participants in the lowest vitamin E tertile (odds ratio, 0.30; 95% confidence interval, 0.10-0.91).

CONCLUSIONS

Our findings show an association between low circulating levels of one of the most important components of the human antioxidant system and the presence of frailty.

Markers of inflammation, vitamin E and peripheral nervous system function: the InCHIANTI study

BACKGROUND

Aging of the peripheral nervous system is associated with several morphologic and functional changes, including a decrease of the nerve conduction velocity. There is evidence that these changes contribute to age-related-decline in muscle strength, sensory discrimination, and autonomic responses. The aim of this study was to characterize the decline in nerve conduction velocity in the peripheral nervous system over the aging process and to identify factors that, independent of age, affect nerve conduction velocity.

METHODS

We measured motor nerve conduction velocity of the right superficial peroneal nerve using a standard neurophysiologic technique in a population-based sample of subjects aged between 20 and 103 years old enrolled in the InCHIANTI study.

RESULTS

Average conduction velocities in the peripheral nerve decreased linearly with age in both sexes. We found that diabetes, cognitive impairment, uric acid, sIL-6R and alpha-tocopherol were significant predictors of nerve conduction velocity independently of the potential confounding effect of age, sex, sex x age interaction term, height, lymphocytes, neutrophils number, alpha1 and alpha2-globulin serum protein.

CONCLUSIONS

Our findings are consistent with the hypothesis that inflammation and inadequate antioxidant defenses are associated with accelerated decline of nerve conduction velocity over the aging process.

Interference of non-specific peroxidases in the fluorescence detection of superoxide radical by hydroethidine oxidation: a new assay for H2O2

The present study shows that hydroethidine (HE), used for in-vivo qualitative fluorescent detection of superoxide anion, can be also oxidized by H2O2 via non-specific peroxidase (horseradish peroxidase and myeloperoxidase) catalysis, forming fluorescent oxidation products. These products give broad excitation/emission peaks (490-495/580-600 nm) near the excitation/emission peaks (475/580 nm) of the HE-superoxide oxidation product, and this may pose serious interference problems to the fluorescent detection of the superoxide radical. The study suggests cautionary use of the HE-superoxide anion assay mainly for detection of reactive oxygen species. A byproduct of this study was the development of a simple and sensitive HE-horseradish peroxidase assay for the in-vitro quantification of H2O2 in biological tissues with a sensitivity of 1 micromol L(-1).

Vitamin E levels, cognitive impairment and dementia in older persons: the InCHIANTI study

There is conflicting evidence that antioxidants contribute to maintaining cognitive function in elderly subjects. We investigated whether vitamin E plasma levels are related to the presence of dementia and cognitive impairment in a population-based cohort study conducted in Italy. A total of 1033 participants aged at least 65 years received clinical and neuropsychological examinations, donated blood for vitamin E analysis and had their diets assessed. Participants with plasma vitamin E levels in the bottom tertile had a significantly higher probability of being demented (OR 2.6, 95% CI 1.0-7.1) and also of suffering from cognitive impairment (OR 2.2, 95% CI 1.2-4.2) compared to those in the highest vitamin E tertile after adjustment for age, gender, education, lipid levels, energy intake, vitamin E intake, and smoking. This study supports the notion that higher vitamin E plasma levels might provide significant protection against cognitive impairment and dementia in elderly subjects.

Antioxidants and physical performance in elderly persons: the Invecchiare in Chianti (InCHIANTI) study

BACKGROUND

Muscle strength and physical performance in old age might be related to the oxidative damage caused by free radicals.

OBJECTIVE

The objective was to assess the correlation of plasma concentrations and daily dietary intakes of antioxidants with skeletal muscle strength and physical performance in elderly persons.

DESIGN

This study is part of the Invecchiare in Chianti (InCHIANTI) study, which was conducted in 986 Italians aged > or = 65 y. Physical performance was assessed on the basis of walking speed, ability to rise from a chair, and standing balance. Knee extension strength was assessed with a hand-held dynamometer. The European Prospective Investigation into Cancer and Nutrition (EPIC) questionnaire was used to evaluate the daily dietary intakes of vitamin C, vitamin E, beta-carotene, and retinol. Plasma alpha- and gamma-tocopherol concentrations were measured. Adjusted linear regression analyses were used to calculate regression coefficients per SD increase in plasma concentrations and daily dietary intakes.

RESULTS

In adjusted analyses, plasma alpha-tocopherol was significantly correlated with knee extension (beta = 0.566, P = 0.003) and the summary physical performance score (beta = 0.044, P = 0.008). Plasma gamma-tocopherol was associated only with knee extension strength (beta = 0.327, P = 0.04). Of the daily dietary intake measures, vitamin C and beta-carotene were significantly correlated with knee extension strength, and vitamin C was significantly associated with physical performance (beta = 0.029, P = 0.04).

CONCLUSIONS

Plasma antioxidant concentrations correlate positively with physical performance and strength. Higher dietary intakes of most antioxidants, especially vitamin C, appear to be associated with higher skeletal muscular strength in elderly persons.

Aortic vasoreactivity during prolonged hypoxia and hypoxia-reoxygenation in senescent rats

To determine the effects of prolonged hypoxia and hypoxia-reoxygenation in senescent blood vessels, isolated aortic rings from 4- and 24-month-old (mo) Wistar rats were submitted to prolonged hypoxia (50 min) or hypoxia/reoxygenation (20 min/30 min) and contractile function recorded. Phenylephrine-induced contraction and sodium nitroprusside- and acetylcholine-induced relaxations were measured after hypoxia or after hypoxia/reoxygenation. In 24 mo group, prolonged hypoxia increased (+83%, P<0.01) and prolonged initial hypoxic contraction, while hypoxic relaxation and delayed contraction were unchanged. Relaxation to acetylcholine was more reduced than in 4 mo group while contraction to phenylephrine and relaxation to sodium nitroprusside were similarly impaired. During reoxygenation, contraction was of same amplitude at both ages and the relaxation to acetylcholine was impaired but to a similar extent in both groups. In conclusion, hypoxic stress induces a greater endothelium-injury in senescent aorta, and increased transient hypoxic contraction, without aggravation of late hypoxic contraction. Aging does not exacerbate the impairment of aortic vasoreactivity after hypoxia-reoxygenation, especially endothelium-dependent relaxation, in sharp contrast to prolonged hypoxia. These age-related changes in vascular sensitivity to oxygen deprivation are different from those observed in coronary arteries, indicating that vasoreactivity during such pathological stress strongly depends on the type of vessel, especially during aging.

Effect of vitamin E intake on levels of vitamins E and C in the central nervous system and peripheral tissues: implications for health recommendations

Vitamin E (alpha-gamma-tocopherol) is an important component in biological membranes. A decrease in its concentration imposes structural and functional damage to the cells. The object of this study was to assess the effect of a graded dietary vitamin E (E) intake on E concentration in specific regions of the brain, and its influence on vitamin C levels and neurological function. Following a 2-month period, rats supplemented with 5, 30, 60, 250 or 500 mg all-rac-alpha-tocopherol-acetate/kg diet (mg E/kg diet) exhibited a significant increase of E concentration in brain and peripheral tissues. However, while blood and liver showed a dose response increase in E concentration which correlated well with the different levels of E in the diet, the central nervous system (CNS) followed the same pattern of increase of vitamin E in brain tissue only when the diet was supplemented with 5, 30, or 60 mg E/kg diet. No further increase in E concentration was observed when the diet was supplemented with 250 or 500 mg E/kg diet. Similarly, the heart tissue showed a significant increase in its E concentration when the was enriched with 5, 30, or 60 mg E/kg diet, with no further increases at 250 or 500 mg. Vitamin C concentration in brain cortex and cerebellum, plasma, liver, and heart was reduced in the groups receiving 250 or 500 mg E/kg diet. Compared to the low E group, rats supplemented with the 60, 250 or 500 mg E/kg diet showed a significant enhancement in striatal dopamine (DA) release, but no differences were observed among the latter three groups.

Differential effects of alpha- and gamma-tocopherol on low-density lipoprotein oxidation, superoxide activity, platelet aggregation and arterial thrombogenesis

OBJECTIVES

This study was designed to examine the differential effects of alpha- and gamma-tocopherol on parameters of oxidation-antioxidation and thrombogenesis.

BACKGROUND

Experimental studies have shown that antioxidants, such as vitamin E (alpha-tocopherol), improve atherosclerotic plaque stability and vasomotor function, and decrease platelet aggregation and tendency to thrombus formation.

METHODS

Sprague Dawley rats were fed chow mixed with alpha- or gamma-tocopherol (100 mg/kg/day) for 10 days. A filter soaked in 29% FeCl3 was applied around the abdominal aorta to study the patterns of arterial thrombosis. The aortic blood flow was observed and continuously recorded using an ultrasonic Doppler flow probe. ADP-induced platelet aggregation, low-density lipoprotein oxidation induced by phorbol 12-myristate 13-acetate (PMA)-stimulated leukocytes, superoxide anion generation and superoxide dismutase (SOD) activity were also measured.

RESULTS

Both alpha- and gamma-tocopherol decreased platelet aggregation and delayed time to occlusive thrombus (all p < 0.05 vs. control). Both alpha- and gamma-tocopherol decreased arterial superoxide anion generation, lipid peroxidation and LDL oxidation (all p < 0.05 vs. control), and increased endogenous SOD activity (p < 0.05). The effects of gamma-tocopherol were more potent than those of alpha-tocopherol (p < 0.05).

CONCLUSIONS

This study indicates that both alpha- and gamma-tocopherol decrease platelet aggregation and delay intraarterial thrombus formation, perhaps by an increase in endogenous antioxidant activity. Gamma-tocopherol is significantly more potent than alpha-tocopherol in these effects.

Multivitamin administration before ischemia reduces ischemia-reperfusion injury in rabbit skeletal muscle

This study investigated the effect of a multivitamin preparation administered before ischemia or before reperfusion, on ischemia-reperfusion (I/R) injury of skeletal muscle. An in vivo hindlimb skeletal muscle I/R model (2.5 h/2 h) was carried out on adult New Zealand white rabbits. Animals used as I/R models were treated with a multivitamin preparation (0.4 ml/kg bw i.v. bolus), containing alpha-tocopherol, ascorbic acid, retinol, vitamin B complex, 30 min before starting ischemia (group MV(isc)) or 5 min before reperfusion (group MV(rep)) and compared to animals with I/R without treatment (group IR) and sham operated animals (group SHAM). Interstitial edema (muscle interfiber area, %MIFA) and changes in microvessel size (microvessel cross sectional area, MVCSA, microm(2)) were measured. Plasma malondialdehyde concentrations (MDA-TBA, nmol/ml) served as a measure of lipid peroxidation. After 2h of reperfusion, ischemia-reperfusion developed a significant microvascular constriction and an interstitial edema (IR, vs SHAM;P<< 0.01), but administration of antioxidative vitamins before the onset of ischemia reduced microvascular constriction and edema formation (P<< 0.05 vs IR group). In a similar manner, administration of vitamins before ischemia lowered plasma MDA-TBA levels as compared to the untreated group during reperfusion (p<< 0. 05). In animals treated with vitamins before reperfusion, the biochemical and morphological results showed no differences as compared to the untreated group. Antioxidative treatment with a multivitamin preparation exerted a beneficial effect on I/R injury of skeletal muscle when the aforementioned vitamins were administered before ischemia but not before the onset of reperfusion.

Vitamin E enhances Ca(2+)-mediated vulnerability of immature cerebellar granule cells to ischemia

The effects of vitamin E on lipid peroxidation, intracellular free Ca2+ concentration ([Ca2+]i), and cell death were investigated in the postischemic immature cerebellum. Deprivation of oxygen and glucose for 10-min in a suspension of freshly dissociated granule cells from the cerebellum of 9-day-old male rat pups resulted in a recovery-induced consumption of cell nonenzymatic antioxidants (ascorbic acid, glutathione, and alpha-tocopherol) and development of membrane lipid peroxidation as measured by the thiobarbituric acid method. The rate of lipid peroxidation of the postischemic cells was stimulated, not reduced, by treatment of the cells with vitamin E (5-30 microM alpha-tocopherol phosphate). In flow-cytometric studies a 10-min period of ischemia resulted in a small increase in intracellular calcium concentration, lipid peroxidation products and cell death, but in the presence of alpha-tocopherol the same treatment caused a dramatic increase in cell death, accompanied by a large increase in [Ca2+]i and lipid peroxidation products. Pretreatment of the cells with a mixture of three antioxidants (vitamin C/rutin/ubiquinol-10, 10/5/1) or nickel (Ni2+) reduced the alpha-tocopherol-induced increases in [Ca2+]i, and cell death. Hydrogen peroxide (1 mM) and the water-soluble analogue of vitamin E, trolox (50 microM), mimicked the effect of vitamin E on lipid peroxidation in the postischemic cells. Pretreatment of the cells with the intracellular Ca2+ chelator BAPTA-AM, reduced both the alpha-tocopherol-induced increase in [Ca2+]i and cell death. The effect of vitamin E on [Ca2+]i was age dependent and decreased abruptly during maturation of the cerebellum between the first and second weeks of life. Results of in vitro treatment of the immature cerebellar cells with the water-soluble form of vitamin E (alpha-tocopherol phosphate) suggest that, after consumption of cellular co-antioxidants, vitamin E may be converted to an alpha-tocopheroxyl radical, which act as a toxic prooxidant as cellular bioenergetics deteriorate.

Protective effects of the thiophosphate amifostine (WR 2721) and a lazaroid (U83836E) on lipid peroxidation in endothelial cells during hypoxia/reoxygenation

Little is known about pharmacological interventions with thiophosphates or lazaroids in endothelial cells injured by hypoxia/reoxygenation with respect to membrane lipid peroxidation (LPO) caused by reactive oxygen species. Therefore, a cell line of bovine aortic endothelial cells was studied after 120-min hypoxia followed by 30-min reoxygenation, resulting in moderate and predominantly reversible injury (energy depression/cytosolic Ca2+-accumulation during hypoxia, which almost normalized during reoxygenation; membrane blebs, an increasing amount of lysosomes, vacuolization, lipofuscin formation, alterations in mitochondria size, some lyzed cells). 18.9 +/- 4.3% of the cells died. Radical-induced LPO measured as malondialdehyde continuously increased to 2.18 +/- 0.17 nmol/mg of protein after reoxygenation vs control (0.41 +/- 0.13, P < 0.05). Simultaneously, the content of 4-hydroxynonenal, a novel indicator of LPO, increased from 0.02 +/- 0.01 to 0.11 +/- 0.02 nmol/mg of protein (P < 0.01). The results support the assumption that reoxygenation injury is accompanied by an increase in membrane LPO, causing structural and functional disturbances in the monolayer. The thiophosphate WR 2721 [S-2-(3-aminopropylamino) ethylphosphorothioic acid] and the lazaroid U83836E [(-)-2-[[4-(2,6-di-1-pyrrolidinyl-4-pyrimidinyl)-1-piperazinyl] methyl]-3,4-dihydro-2,5,7,8-tetramethyl-2H-1-benzopyran-6-ol (dihydrochloride)] were effective scavengers of .OH, being more efficient than trolox C (6-hydroxy-2,5,7,8-tetramethylchroman-2-carbon acid) used as standard (EC50: 12, 5 and 15 microM, respectively, measured by electron spin resonance spectroscopy). One mM WR 2721, 10 microM U83836E, and 5 microM trolox C reduced formation of malondialdehyde during hypoxia/reoxygenation to 53 +/- 7, 51 +/- 10 and 48 +/- 6%, respectively (P < 0.05 each, versus control). In general, WR 2721 and U83836E prevent radical-induced membrane LPO in a model of endothelial cells injured by hypoxia/reoxygenation. The use of these two agents is a new approach to protect the endothelium against oxidative stress.

Inhibitory effects of antioxidants on neonatal rat cardiac myocyte hypertrophy induced by tumor necrosis factor-alpha and angiotensin II

BACKGROUND

Tumor necrosis factor-alpha (TNF-alpha) and angiotensin II (Ang II) modulate heart failure in part by provoking the hypertrophic response. Signal transduction pathways of those factors are implicated in reactive oxygen intermediates (ROIs). Therefore, we hypothesized that TNF-alpha and Ang II might cause myocyte hypertrophy via the generation of ROIs.

METHODS AND RESULTS

To test the hypothesis, we tested whether TNF-alpha and Ang II could induce the generation of ROIs and whether antioxidants such as butylated hydroxyanisole (BHA), vitamin E, and catalase might inhibit the hypertrophy in cultured neonatal rat cardiac myocytes. ROIs were measured by the ROI-specific probe 2',7'-dichlorofluorescin diacetate in cultured cardiac myocytes. We demonstrated that TNF-alpha and Ang II induced the generation of ROIs in a dose-dependent manner. TNF-alpha (10 ng/mL) and Ang II (100 nmol/L) enlarged cardiac myocytes and increased [3H]leucine uptake, and BHA (10 micromol/L) significantly inhibited both effects. Other antioxidants, such as vitamin E (1 microg/mL) and catalase (100 U/mL), also inhibited the enlargement of cardiac myocytes induced by TNF-alpha.

CONCLUSIONS

These results indicate that TNF-alpha and Ang II cause hypertrophy in part via the generation of ROIs in cardiac myocytes.

Influence of vitamin E succinate on retinal cell survival

In this study, we analyzed the influence of vitamin E succinate (5-80 microM), supplemented in the culture medium, on the survival of cultured retinal cells. The release of lactate dehydrogenase (LDH) was decreased in the presence of low concentrations (10-20 microM) of vitamin E succinate, whereas high concentrations (80 microM) induced a significant increase (about 2-fold) in the release of LDH, indicating a reduction of plasma membrane integrity. Supplementing with vitamin E succinate (80 microM) greatly enhanced its cellular content, as compared to vitamin E acetate (80 microM), and the membrane order of the retinal cells, as evaluated by the fluorescence anisotropy (r) of TMA-DPH (1-(4-(trimethylammonium)-phenyl)-6-phenylhexa-1,3,5-triene), was not altered. Furthermore, vitamin E succinate was more potent than vitamin E acetate in reducing thiobarbituric acid reactive substances (TBARS) formation upon ascorbate-Fe2+-induced oxidative stress (TBARS formation after cell oxidation decreased by about 15-fold or 1.6 fold, respectively, in the presence of 20 microM vitamin E succinate or 20 microM vitamin E acetate). A decrease in MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) reduction induced by supplementing with vitamin E succinate (80 microM), to 35.99 +/- 1.96% as compared to the control, but not by vitamin E acetate (80 microM), suggests that vitamin E succinate may affect the mitochondrial activity. Vitamin E succinate also reduced significantly the ATP:ADP ratio in a dose-dependent manner, indicating that vitamin E succinate-mediated cytotoxic effects involve a decrement of mitochondrial function.

Effect of alpha-tocopherol pretreatment on high energy metabolites in rabbit skeletal muscle after ischemia-reperfusion

The ability of skeletal muscle to recover high energy phosphate compounds in response to pretreatment with vitamin E was investigated in a rabbit hindlimb ischemia/reperfusion model (2. 5 h/2 h). High energy metabolites were measured in the adductor magnus muscle of untreated animals and compared to the treatment group (all rac-alpha-tocopheryl acetate, 3 mg/kg body weight, supplemented i.v. before the onset of ischemia). Phosphocreatine (PCr) levels decreased after ischemia more than 65% in untreated and treatment groups, but tended to recover in treatment group after reperfusion. Adenosine triphosphate (ATP) values decreased by 50% of basal level after reperfusion in the untreated group, whereas alpha-tocopherol pretreatment prevented ATP depletion.

Effect of vitamin E on human aortic endothelial cell responses to oxidative injury

Reactive oxygen species produced by the cells present in the arterial wall may cause oxidative damage to cellular components altering endothelial cell (EC) function. Changes in the EC function appear to play a key role in the pathogenesis of atherosclerosis. Human aortic endothelial cells (HAEC) were employed to investigate the protective role of vitamin E upon exposure of endothelial cells to oxidative stress in vitro. HAEC assimilate d-alpha-tocopherol from the media in a dose-dependent manner. Exposure of HAEC to 16.5 mM of the free radical generator 2,2'-azobis (2-amidinopropane) hydrochloride (AAPH) for 16 h decreased cell viability (assessed by trypan blue exclusion) from 90 to 28%. HAEC preincubated with vitamin E at 15, 30, and 60 microM prior to the AAPH exposure resulted in a dose-dependent increase in resistance to oxidative stress and increased cell viability by 37, 66, and 85%, respectively. An increase in prostacyclin (PGI2) production by HAEC in response to AAPH exposure was correlated positively with cell damage and negatively with vitamin E concentration. Interleukin (IL)-1 production also increased in parallel with cell damage induced by AAPH. Vitamin E treatment significantly reduced IL-1 production after AAPH exposure. This modulatory role of vitamin E on HAEC function following exposure to an oxidative stress may reflect its antioxidant protection against lipid peroxidation.