Effect of acetate on molecular and physiological aspects of Clostridium beijerinckii NCIMB 8052 solvent production and strain degeneration

OBJECTIVES: The purpose of this study was to test the hypothesis that long-term supplementation with Vitamin E improves endothelium-dependent relaxation in hypercholesterolemia patients and/or chronic smoking, two risk factors that have been shown to be associated with increased radical formation. BACKGROUND: Experimental evidence suggests that oxidized low density lipoprotein (LDL) impairs endothelium-dependent relaxation, and vitamin E, a lipid-soluble antioxidant, reduces the oxidation of LDL. METHODS: Thirteen subjects with hypercholesterolemia, 14 smokers and 15 hypercholesterolemic smokers were enrolled in a double-blind, placebo-controlled study. After baseline measurements of plasma autoantibodies against oxidized LDL and assessment of endothelium-dependent relaxation using intra-arterial forearm infusions of acetylcholine, participants within each group were randomly assigned in a 1:2 fashion to receive either placebo or vitamin E for 4 months, when plasma levels of autoantibodies against oxidized LDL and vascular function were reassessed. RESULTS: Vitamin E significantly augmented endothelium-dependent relaxation in hypercholesterolemic smokers but not in patients with either hypercholesterolemia or chronic smoking. At baseline, hypercholesterolemic smokers had significantly higher autoantibody levels against oxidized LDL (compared with the other two groups), which were significantly reduced after 4 months of vitamin E supplementation. There was a significant relationship between improvement in acetylcholine-induced vasodilation and the change in autoantibody titer against oxidized LDL (r = -0.59; p = 0.002). CONCLUSIONS: Long-term vitamin E supplementation improves endothelium-dependent relaxation in forearm resistance vessels of hypercholesterolemic smokers, which are characterized by increased levels of autoantibodies against oxidized LDL. These findings may suggest that the beneficial effect of vitamin E is confined to subjects with increased exposure to oxidized LDL.     

Lipoprotein oxidation, antioxidants and cardiovascular risk: epidemiologic evidence

This review summarizes the scientific evidence for a possible role of antioxidants in the prevention of coronary heart disease (CHD). Dietary antioxidants include vitamin E, vitamin C and beta-carotene, whereas selenium is an integral part of the antioxidant enzyme glutathione peroxidase. Experimental studies suggest that the oxidation of low-density lipoproteins (LDL) in the vessel wall plays an important role in the development of atherosclerotic lesions. The resistance of LDL to oxidation is increased by antioxidant supplementation, at least in vitro. Epidemiological studies have not demonstrated unequivocally that a high intake of antioxidants leads to a decreased risk of CHD. Studies on dietary intake and serum levels of antioxidants do point in the direction of a preventive effect of antioxidants, whereas the results of intervention studies are less conclusive. Beta-carotene supplementation is not associated with any decrease in CHD; high doses of vitamin E may be beneficial, but results from large trials are to be awaited. General preventive measures based on antioxidant supplementation are not yet justifiable.     

Atherosclerosis, with special reference to vitamin E

The relationship between atherosclerosis and fat soluble vitamin, especially vitamin E is reviewed on the basis of oxidised modification of low density lipoprotein (LDL). Data now support the notion that the oxidised LDL is present in the blood and arterial wall and antioxidant drugs such as probucol and vitamin E, beta-carotene, may prevent the progression of atherosclerosis. LDL alpha-tocopherol levels are generally correlated to the plasma concentrations and supplementation with alpha-tocopherol increases its content in LDL. There is a significant correlation between the LDL alpha-tocopherol level and the resistance to oxidative modification. Epidemiological data also shows the relation between low levels of plasma vitamin E and the increased incidence of coronary heart disease. Clinical application of vitamin E should be clarified in detail to inhibit the progression of atherosclerosis.     

Vitamin supplementation therapy in the elderly

Vitamin supplementation in large dosages is increasingly common in the older population. Often, such supplementation is used in an attempt to improve an individual's health status. There have been claims that the effects of vitamins halt the normal aging process or prevent and cure disease. However, several recent studies have failed to demonstrate the efficacy of vitamin supplementation in preventing several types of cancer. In moderate dosages, supplementation with vitamin E (tocopherols) shows promise as a lipid antioxidant, and may reduce the risk of coronary heart disease. However, before vitamin E becomes an accepted medical therapy, further long term studies must be undertaken to examine the safety and efficacy of such therapy. An adequate intake of vitamins should be ensured by adherence to a well balanced diet. However, the elderly are prone to circumstances that may prevent them from eating a balanced diet. In addition, there are several age-related medical conditions that may predispose individuals to dietary and vitamin deficiencies. To prevent vitamin deficiency diseases and their associated morbidity, modest vitamin supplementation may be necessary. However, supplementation should be reserved for individuals with documented deficiency or who are at risk of developing such deficiencies, especially those who are homebound or institutionalised. Vitamins taken in large dosages should be considered as drugs. These medicines, which are obtainable over-the-counter, should be carefully regulated to prevent toxicity.     

A high concentration of melatonin inhibits in vitro LDL peroxidation but not oxidized LDL toxicity toward cultured endothelial cells

The pineal hormone, melatonin, was recently found to be a potent free scavenger for hydroxyl and peroxyl radicals. Melatonin also inhibits neuronal and thymocyte damage due to oxidative stress. Atherosclerosis development is mediated by low-density lipoprotein (LDL) oxidation and the endocytosis of oxidized LDL by resident macrophages in the subendothelial vascular wall. Furthermore, the cytotoxic effect of oxidized LDL increases atherogenicity. The goal of this study was to compare the antioxidant activities of melatonin and vitamin E against in vitro LDL oxidation and their cytoprotective actions against oxidized LDL-induced endothelial cell toxicity. An attempt at loading LDL with melatonin by incubating human plasma with an ethanolic melatonin solution gave only low protection against Cu2+-induced LDL oxidation in comparison with vitamin E and gave no detectable incorporation of melatonin into LDL, measured by high-performance liquid chromatography (HPLC) coupled to UV detection. High concentrations of melatonin (10-100 microM) added to the oxidative medium induced a clear inhibition of Cu2+-induced LDL oxidation, characterized as an increase in the lag-phase duration of conjugated diene formation and decreases in the maximal rate of the propagation phase and in the maximal amount of conjugated diene formation. Determination of the median efficacious dose (ED50) of melatonin and vitamin E by their ability to increase lag-phase duration showed that melatonin was less active than vitamin E (ED50, 79 vs. 10 microM, respectively). Melatonin was also less active than vitamin E in limiting the formation of thiobarbituric acid-reactive substances (TBARS) and LDL fluorescence intensity increase in the medium during Cu2+-induced LDL oxidation. Cu2+-induced LDL oxidation in the presence of 100 microM melatonin produced oxidized LDLs that were less recognizable for the scavenger receptors of J774 macrophages than were untreated LDLs. Vitamin E, 10 microM, was more active than 100 microM melatonin in inhibiting LDL oxidation and the resulting lipoprotein alterations leading to binding internalization and degradation by the J774 macrophages. Vitamin E, 100 microM, inhibited the pursuit of the oxidation of oxidized LDL mediated by bovine aortic endothelial cells (BAECs) in a culture medium containing Cu2+, whereas 100 microM melatonin had no antioxidant effect. Melatonin, 100 microM, as well as 100 microM vitamin E inhibited intracellular TBARS formation during the incubation of BAECs with highly oxidized LDL but had no influence on the increase in glutathione (GSH) concentration during this lengthy exposure (16 h) of BAECs to highly oxidized LDL. During this period, the same dose of vitamin E but not of melatonin tended to limit the decrease in adenosine triphosphate (ATP) concentration. Vitamin E, 100 microM, did not significantly reduce cellular lactate dehydrogenase (LDH) release in the culture medium during the incubation of oxidized LDL with BAECs, whereas 100 microM melatonin dramatically increased this release. These data show that melatonin is less active than vitamin E in inhibiting in vitro LDL oxidation and does not inhibit the cytotoxicity of oxidized LDL toward cultured endothelial cells. The concentrations necessary to inhibit LDL oxidation are far beyond those found in human plasma (100 microM vs. 100 pM). Therefore our results indicate that the pineal hormone melatonin per se appears to have little antiatherogenic property in the in vitro oxidation of LDL and the cytoprotective action against the toxicity of oxidized LDL. Nevertheless, in vivo LDL oxidation takes place in the subendothelium of the artery wall, and nothing is known about the concentration of melatonin or its catabolites in this environment.     

Oxidative stress in critical care: is antioxidant supplementation beneficial?

Reactive oxygen species (ROS) are constantly produced in human beings under normal circumstances. Antioxidant systems help defend the body against ROS but may be overwhelmed during periods of oxidative stress, which can cause lipid peroxidation, damage to DNA, and cell death. Critical illness, such as sepsis or adult respiratory distress syndrome, can drastically increase the production of ROS and lead to oxidative stress. Sources of oxidative stress during critical illness include activation of the phagocytic cells of the immune system (the respiratory burst), the production of nitric oxide by the vascular endothelium, the release of iron and copper ions and metalloproteins, and the vascular damage caused by ischemia reperfusion. Only indirect measurements of ROS are available, but the presence of oxidative stress in critical illness is supported by clinical studies. In general, serum antioxidant vitamin concentrations seem to decrease and measures of oxidative stress seem to increase in critically ill populations. Oxidative stress has been associated with sepsis, shock, a need for mechanical ventilation, organ dysfunction, acute respiratory distress syndrome, disseminated intravascular coagulation, surgery, and the presence of an acute-phase response. In addition, higher levels of oxidative stress seem to occur in patients with more notable injuries. Dietary supplementation with antioxidant vitamins seems to be the logical answer to decreasing serum antioxidant concentrations, but antioxidants may have adverse effects. The benefit of supplementing antioxidants in critically ill populations has not been shown and requires further study.     

Cosupplementation with coenzyme Q prevents the prooxidant effect of alpha-tocopherol and increases the resistance of LDL to transition metal-dependent oxidation initiation

There is considerable interest in the ability of antioxidant supplementation, in particular with vitamin E, to attenuate LDL oxidation, a process implicated in atherogenesis. Since vitamin E can also promote LDL lipid peroxidation, we investigated the effects of supplementation with vitamin E alone or in combination with coenzyme Q on the early stages of the oxidation of isolated LDL. Isolated LDL was obtained from healthy subjects before and after in vitro enrichment with vitamin E (D-alpha-tocopherol, alpha-TOH) or dietary supplementation with D-alpha-TOH (1 g/d) and/or coenzyme Q (100 mg/d). LDL oxidation initiation was assessed by measurement of the consumption of alpha-TOH and cholesteryl esters containing polyunsaturated fatty acids and the accumulation of cholesteryl ester hydroperoxides during incubation of LDL in the transition metal-containing Ham's F-10 medium in the absence and presence of human monocyte-derived macrophages (MDMs). Native LDL contained 8.5 +/- 2 molecules of alpha-TOH and 0.5 to 0.8 molecules of ubiquinol-10 (CoQ10H2, the reduced form of coenzyme Q) per lipoprotein particle. Incubation of this LDL in Ham's F-10 medium resulted in a time-dependent loss of alpha-TOH with concomitant stoichiometric conversion of the major cholesteryl esters to their respective hydroperoxides. MDMs enhanced this process. LDL lipid peroxidation occurred via a radical chain reaction in the presence of alpha-TOH, and the rate of this oxidation decreased on alpha-TOH depletion. In vitro enrichment of LDL with alpha-TOH resulted in an LDL particle containing sixfold to sevenfold more alpha-TOH, and such enriched LDL was more readily oxidized in the absence and presence of MDMs compared with native LDL. In vivo alpha-TOH-deficient LDL, isolated from a patient with familial isolated vitamin E deficiency, was highly resistant to Ham's F-10-initiated oxidation, whereas dietary supplementation with vitamin E restored the oxidizability of the patient's LDL. Oral supplementation of healthy individuals for 5 days with either alpha-TOH or coenzyme Q increased the LDL levels of alpha-TOH and CoQ10H2 by two to three or three to four times, respectively. alpha-TOH-supplemented LDL was significantly more prone to oxidation, whereas CoQ10H2-enriched LDL was more resistant to oxidation initiation by Ham's F-10 medium than native LDL. Cosupplementation with both alpha-TOH and coenzyme Q resulted in LDL with increased levels of alpha-TOH and CoQ10H2, and such LDL was markedly more resistant to initiation of oxidation than native or alpha-TOH-enriched LDL. These results demonstrate that oral supplementation with alpha-TOH alone results in LDL that is more prone to oxidation initiation, whereas cosupplementation with coenzyme Q not only prevents this prooxidant activity of vitamin E but also provides the lipoprotein with increased resistance to oxidation.     

Regulation of inducible nitric oxide synthase (iNOS) and GTP cyclohydrolase I (GTP-CH I) gene expression by ox-LDL in rat vascular smooth muscle cells

The generation of nitric oxide is regulated by several factors, including the substrates and cofactors supplementation. Decreased expression and activity of nitric oxide synthase as well as diminished amount of L-arginine or enzyme cofactors results in the inhibition of nitric oxide generation in vascular wall cells. GTP cyclohydrolase 1 is a key enzyme involved in the synthesis of tetrahydrobiopterin, one of the most important cofactors of NO synthases. We have demonstrated that oxidized LDL inhibit not only inducible nitric oxide synthase gene expression but also GTP cyclohydrolase I gene expression in interleukin-1 beta activated rat vascular smooth muscle cells in vitro. It is postulated that diminished availability of tetrahydrobiopterin may additionally impair the generation of nitric oxide in atherosclerosis.     

Peroxidation of LDL from combined-hyperlipidemic male smokers supplied with omega-3 fatty acids and antioxidants

The effects of marine omega-3 polyunsaturated fatty acids (FAs) and antioxidants on the oxidative modification of LDL were studied in a randomized, double-blind, placebo-controlled trial. Male smokers (n = 41) with combined hyperlipidemia were allocated to one of four groups receiving supplementation with omega-3 FAs (5 g eicosapentaenoic acid and docosahexaenoic acid per day), antioxidants (75 mg vitamin E, 150 mg vitamin C, 15 mg beta-carotene, and 30 mg coenzyme Q10 per day), both omega-3 FAs and antioxidants, or control oils. LDL and human mononuclear cells were isolated from the patients at baseline and after 6 weeks of supplementation. LDL was subjected to cell-mediated oxidation by the patients' own mononuclear cells, as well as to Cu(2+)-catalyzed and 2,2'-azobis-(2-amidinopropane hydrochloride) (AAPH)-initiated oxidation. Extent of LDL modification was measured as lag time, the formation rate of conjugated dienes (CDs), the maximum amount of CDs formed, formation of lipid peroxides, and the relative electrophoretic mobility of LDL on agarose gels. Dietary supplementation with omega-3 FAs increased the concentration of total omega-3 FAs in LDL and reduced the concentration of vitamin E in serum. The omega-3 FA-enriched LDL particles were not more susceptible to Cu(2+)-catalyzed, AAPH-initiated, or autologous cell-mediated oxidation than control LDL. In fact, enrichment with omega-3 FAs significantly reduced the formation rate of CDs when LDL was subjected to AAPH-induced oxidation. Supplementation with moderate amounts of antioxidants significantly increased the concentration of vitamin E in serum and increased the resistance of LDL to undergo Cu(2+)-catalyzed oxidation, measured as increased lag time, reduced formation of lipid peroxides, and reduced relative electrophoretic mobility compared with control LDL. Supplementation with omega-3 FAs/antioxidants showed oxidizability of LDL similar to that of control LDL and omega-3 FA-enriched LDL. In conclusion, omega-3 FAs neither rendered the LDL particles more susceptible to undergo in vitro oxidation nor influenced mononuclear cells' ability to oxidize autologous LDL, whereas moderate amounts of antioxidants protected LDL against oxidative modification.     

Can vitamin E prevent development of coronary heart disease?

Oxidation of low-density lipoprotein (LDL) probably plays an important part in atherosclerosis. Vitamin E (alpha-tocopherol) is a potent antioxidant carried in LDL. It increases the resistance of LDL to oxidation, thereby, among other things, inhibiting foam cell formation and proliferation of smooth muscle cells. Some animal experiments have indicated that vitamin E retards the development of atherosclerotic lesions. Observational studies (case-control and cohort) have shown that long-term treatment with vitamin E is associated with lower incidence of coronary heart disease in men and women alike. Randomisation to vitamin E in a large placebo controlled trial gave a nonsignificant reduction in mortality from ischemic heart disease. Although vitamin E seems to reduce the risk of coronary heart disease, randomised trials of adequate size are necessary in both secondary and primary prevention in order to test this. Such trials are in progress.     

Changes in rat alveolar macrophageal antioxidant defense and reactive oxygen species release by high dietary vitamin E

For the past decade there has been emphasis on the immunomodulatory effects of vitamin E apart from its established role as a free radical scavenger. In alveolar macrophages (AMs), the role of vitamin E supplementation has not yet been investigated sufficiently. In the present study we have evaluated the effects of high vitamin E (DL-alpha-tocopheryl acetate, alpha-TA) supplementation for 10 d on rat-alveolar macrophageal antioxidant defense and reactive oxygen species (ROS) release. There was an increase in plasma vitamin E content from 5.22 +/- 1.30, at 50 mg to 12.23 +/- 1.06 and 22.32 +/- 2.02 micrograms/mL at 250 and 1,250 mg alpha-TA/kg dietary supplementation. Alveolar macrophage-vitamin E content enhanced by 56 to 75% at 250 and 1,250 mg alpha-TA diet as compared with control diet. Superoxide dismutase activity decreased and catalase and glutathione peroxidase activities increased significantly in AMs of 250 and 1,250 mg alpha-TA diet-fed rats. Reduced glutathione, total glutathione, and glutathione-S-transferase activity in AMs did not change significantly at any of the high doses of alpha-TA supplementation. On stimulation of AMs by phorbol-12-myristate-13-acetate (PMA), there was 2.8- and 3.5-fold enhancement in superoxide (O2-.) and H2O2 production, respectively, at 50 mg alpha-TA dose. But this increase by PMA could not take place in AMs from animals supplemented with 250 and 1,250 mg alpha-TA. It may therefore be concluded that high alpha-TA supplementation in diet may equip the AMs with a stronger defense against oxygen-free radical mediated damage to them.     

Cytokine regulation on the synthesis of nitric oxide in vivo by chronically infected human polymorphonuclear leucocytes

1 We tested the hypothesis that lowering antioxidant protection through dietary vitamin E deprivation would alter active and passive mechanical properties in resistance arteries of the rat. Specifically, we hypothesized that vascular tone in isolated mesenteric arteries of the vitamin E-deprived rats would be altered due to impaired endothelial influences of nitric oxide and/or prostaglandins. 2 Lumen diameter and wall thickness were measured in pressurized arteries (approximately 250 microm diameter) from control (n=9) and vitamin E deprived (n=9) Sprague-Dawley female rats by use of a dimension analysing system. 3 Treatment with a cyclo-oxygenase inhibitor (meclofenamate) did not affect the basal vascular tone in either group. Treatment with a nitric oxide synthase inhibitor (NG-methyl-L-arginine) caused a significant increase in basal tone only in the vitamin E-deprived rats (% tone: 6.2+/-1.1 vs 1.2+/-0.3%; P<0.05). When tone was induced to 25% of the initial diameter with phenylephrine, treatment with the nitric oxide synthase inhibitor resulted in a greater potentiated tone in the vitamin E-deprived rats compared to the controls (26.5+/-2.7 vs 16.4+/-3.4%; P<0.05); suggesting a greater nitric oxide affect in the vessels from the vitamin E-deprived rats. Meclofenamate treatment in the induced tone arteries significantly relaxed (-17.4+/-4.0%; P<0.05) only the arteries from the vitamin E-deprived rats, indicating that a vasoconstrictor was modifying tone. The passive characteristics of distensibility and stress-strain relationship were not different between the two groups of rats. 4 In summary, vitamin E deprivation in the rat enhanced the modulation of vascular tone by both the nitric oxide and cyclo-oxygenase pathways but did not alter passive characteristics of mesenteric arteries.     

The inhibitory effect of endogenous estrogen metabolites on copper-mediated in vitro oxidation of LDL

The antioxidant effects of 17beta-estradiol, its main A- and D-ring metabolites, and of vitamin E were compared in vitro. Low density lipoprotein (LDL) was isolated from fresh human blood, and LDL oxidation was evaluated spectrometrically by monitoring diene formation of fatty acids. All substances tested exhibited antioxidant potential. The A-ring metabolites (catecholestrogens) emerged as more potent inhibitors of LDL oxidation than the parent substance estradiol, its D-ring metabolites, and vitamin E. Since oxidized LDL seems to play a crucial role in the development of atherosclerosis, its inhibition may be of preventive value. In summary, A-ring metabolites of estradiol (catecholestrogens), substances that occur naturally in the body, may be involved in the physiologic inhibition of LDL oxidation.     

Vitamin C blocks inflammatory platelet-activating factor mimetics created by cigarette smoking

Cigarette smoking within minutes induces leukocyte adhesion to the vascular wall and formation of intravascular leukocyte-platelet aggregates. We find this is inhibited by platelet-activating factor (PAF) receptor antagonists, and correlates with the accumulation of PAF-like mediators in the blood of cigarette smoke-exposed hamsters. These mediators were PAF-like lipids, formed by nonenzymatic oxidative modification of existing phospholipids, that were distinct from biosynthetic PAF. These PAF-like lipids induced isolated human monocytes and platelets to aggregate, which greatly increased their secretion of IL-8 and macrophage inflammatory protein-1alpha. Both events were blocked by a PAF receptor antagonist. Similarly, blocking the PAF receptor in vivo blocked smoke-induced leukocyte aggregation and pavementing along the vascular wall. Dietary supplementation with the antioxidant vitamin C prevented the accumulation of PAF-like lipids, and it prevented cigarette smoke-induced leukocyte adhesion to the vascular wall and formation of leukocyte-platelet aggregates. This is the first in vivo demonstration of inflammatory phospholipid oxidation products and it suggests a molecular mechanism coupling cigarette smoke with rapid inflammatory changes. Inhibition of PAF-like lipid formation and their intravascular sequela by vitamin C suggests a simple dietary means to reduce smoking-related cardiovascular disease.     

Influence of natural antioxidants on in vitro lipoprotein oxidation

Susceptibility of low-density lipoproteins (LDL) to oxidation might be a critical risk factor in the development and progression of atherosclerosis. The oxidation involves the degradation of polyunsaturated fatty acids, the formation of lysolecithin, oxysterols and aldehyde modification of lysine residues on Apo B100. The oxidation products have a number of biological activities such as cytotoxicity, atherogenesis, and carcinogenesis. The aim of this study was to investigate the in vitro antioxidant effects of vitamins E, A, and C on LDL. LDL was isolated from plasma by density gradient high-speed centrifugation and used as 0.1 microM/l isotonic solution. LDL oxidation was triggered by simple incubation with Cu2+ (1, 2, 5, 10, 12, 20 microM/l), in absence or presence of lipid-soluble or water-soluble antioxidants in different concentrations (tocopherols--0.5, 1, 2, and 4 microM/l; cerotenoids--0.1, 0.2, and 0.4 microM/l; ascorbate--2.5, 5, and 10 microM/l). The LDL oxidability was measured by continuous spectrophotometrical monitoring at 234 nm of the increased formation of conjugated diene hydroperoxides. The oxidation curves showed a profile with an inhibition period followed by a propagation period and were quantitatively characterized by two parameters: lag-phase (expressed in minutes), and propagation rate (expressed in changes of absorbance--delta E234nm/min). Lag-phase--the period of inhibition oxidation--was attributed to the ability of LDL (by antioxidants) to resist oxidation in vitro. LDL lag-phase decreased and propagation rate increased with the increasing of copper concentration. In conclusion: 1) susceptibility of LDL to oxidation depends on both the concentration of pro-oxidant stimuli and the entity and concentrations of antioxidants; 2) antioxidants retard the process through which LDL undergo oxidation in vitro when exposed to copper ions; 3) a synergistic effect may also be involved, as water-soluble vitamin C keeps the fat-soluble vitamin E and vitamin A within LDL.     

Haloperidol and apomorphine differentially affect neuropeptidase activity

The effects of lipid peroxidation and the antioxidant vitamin E contained in LDL isolated from control plasma (LDL--) and from plasma preincubated with 0.5 mmol/ml alpha-tocopherol (LDL+) on the proliferation of estrogen-receptor positive (ER+ : ZR-75, T-47-D, MCF-7) and negative (ER--: HBL-100, MDA-MB-231) human breast cancer cells were studied. Human skin fibroblasts served as controls. Incubation of plasma with 0.5 mmol/ml alpha-tocopherol resulted in a 3-fold increase of its content and a significant reduction in lipid hydroperoxides and conjugated dienes in LDL. Incubation of fibroblasts or ER+ tumor cells with LDL- or LDL+ had an effect on neither cell proliferation nor on the cellular levels of peroxidation products as compared to control incubations in the absence of LDL. In ER- cells, however, LDL+ stimulated the proliferation, whereas LDL- yielded a cytotoxic effect. Moreover, LDL- supplementation resulted in an increase in the content of hydroperoxides and conjugated dienes. LDL+ supplemented cells exhibited hydroperoxide levels in these tumor cells comparable to the basal levels measured in the absence of LDL. Our data suggested that peroxidation products in LDL are cytotoxic to estrogen-receptor negative breast tumor cells and vitamin E counteracts this effect.     

Vitamin E/lipid peroxide ratio and susceptibility of LDL to oxidative modification in non-insulin-dependent diabetes mellitus

The presence of conventional risk factors cannot sufficiently account for the excess risk of atherosclerosis in patients with non-insulin-dependent diabetes mellitus (NIDDM). Oxidative modification of LDL has been implicated in the pathogenesis of coronary atherosclerosis. Thirty-five patients with NIDDM, 20 nondiabetic, hypertriglyceridemic subjects (HTG-control), and 21 diabetic, normotriglyceridemic subjects (NTG-control) were enrolled in this study. Oxidative susceptibility of LDL was determined by monitoring formation of conjugated dienes. Mean lag time of LDL oxidation and vitamin E/lipid peroxide of LDL was lower in patients with NIDDM (43.2 +/- 3.9 minutes and 1.6 +/- 1.3) than in HTG-control (48.8 +/- 3.2 minutes and 2.3 +/- 1.2, respectively) and NTG-control subjects (54.2 +/- 6.1 minutes and 3.0 +/- 1.8, respectively). Mean LDL particle size in patients with NIDDM and HTG-control subjects (24.4 +/- 0.9 and 24.7 +/- 0.7 nm, respectively) was smaller than in NTG-control subjects (25.9 +/- 1.0 nm). Multiple stepwise regression analyses ascertained that the vitamin. E/lipid peroxide of LDL is a major determinant of LDL oxidation lag time. These results suggest that LDL in patients with NIDDM is more susceptible to oxidative modification primarily because of a reduced level of vitamin E/lipid peroxide of LDL. The enhanced susceptibility of LDL to oxidation may be a pivotal factor underlying the increased incidence of vascular disease in patients with NIDDM.     

In vivo formation of 8-Epi-prostaglandin F2 alpha is increased in hypercholesterolemia

F2-isoprostanes are bioactive prostaglandin (PG)-like compounds that are produced from arachidonic acid through a nonenzymatic process of lipid peroxidation catalyzed by oxygen free-radicals. 8-Epi-PGF2 alpha may amplify the platelet response to agonists, circulates in plasma, and is excreted in urine. We examined the hypothesis that the formation of 8-epi-PGF2 alpha is altered in patients with hypercholesterolemia and contributes to platelet activation in this setting. Urine samples were obtained from 40 hypercholesterolemic patients and 40 age- and sex-matched control subjects for measurement of immunoreactive 8-epi-PGF2 alpha. Urinary excretion of 11-dehydro-thromboxane (TX) B2, a major metabolite of TXA2, was measured as an in vivo index of platelet activation. Low-dose aspirin, indobufen, and vitamin E were used to investigate the mechanism of formation and effects of 8-epi-PGF2 alpha on platelet activation. Urinary 8-epi-PGF2 alpha was significantly (P = .0001) higher in hypercholesterolemic patients than in control subjects: 473 +/- 305 versus 205 +/- 95 pg/mg creatinine. Its rate of excretion was inversely related to the vitamin E content of LDL and showed a positive correlation with urinary 11-dehydro-TXB2. Urinary 8-epi-PGF2 alpha was unchanged after 2-week dosing with aspirin and indobufen despite complete suppression of TX metabolite excretion. Vitamin E supplementation was associated with dose-dependent reductions in both urinary 8-epi-PGF2 alpha and 11-dehydro-TXB2 by 34% to 36% and 47% to 58% at 100 and 600 mg daily, respectively. We conclude that the in vivo formation of the F2-isoprostane 8-epi-PGF2 alpha is enhanced in the vast majority of patients with hypercholesterolemia. This provides an aspirin-insensitive mechanism possibly linking lipid peroxidation to amplification of platelet activation in the setting of hypercholesterolemia. Dose-dependent suppression of enhanced 8-epi-PGF2 alpha formation by vitamin E supplementation may contribute to the beneficial effects of antioxidant treatment.     

Mutations in fibroblast growth-factor receptor 3 in sporadic cases of achondroplasia occur exclusively on the paternally derived chromosome

OBJECTIVES: The aim of this study was to determine whether the combination of lipid-lowering therapy and vitamin E supplementation improves peripheral endothelial function and whether it is more effective than lipid-lowering therapy alone. BACKGROUND: Endothelium-dependent vasodilation is impaired in coronary and peripheral arteries of patients with hypercholesterolemia. Coronary endothelial function has been shown to improve under lipid-lowering and antioxidant therapy, but the effect of additive vitamin E supplementation in the brachial artery is unknown. METHODS: Seven patients with hypercholesterolemia (mean+/-SD; age 51+/-10 yr) were studied. Endothelium-dependent, flow-mediated dilation (FMD) and endothelium-independent nitroglycerin-induced dilation (NMD) were assessed in the brachial artery using high resolution ultrasound 1) at baseline (BL I), 2) after 8 weeks of simvastatin (20 mg) and vitamin E (300 IU) therapy (Comb I), 3) after withdrawal of vitamin E for 4 weeks (Statin), 4) after therapy as in #2 for 4 weeks (Comb II) and 5) after withdrawal of both drugs for 4 weeks (BL II). RESULTS: Combined simvastatin and vitamin E therapy reduced total cholesterol (Comb I vs. BL I: 276+/-22 vs. 190+/-14 mg/dl, p < 0.0001) and low-density lipoprotein (LDL)-C (197+/-22 vs. 106+/-22 mg/dl, p < 0.00001), augmented alpha tocopherol levels normalized to LDL (12.2+/-4.1 vs. 4.9+/-0.9 microg alpha-T/100 mg% LDL-C, p < 0.01) and resulted in significant improvements in FMD (16.4+/-4.7 vs. 4.9+/-2.5%, p < 0.001) as well as NMD (17.9+/-4.3 vs. 11.2+/-2.8%, p < 0.01). The ratio of FMD to NMD (0.92+/-0.17 vs. 0.46+/-0.24%, p < 0.05) also increased under combination therapy, indicating a greater improvement of FMD than that of NMD. After withdrawal of vitamin E, both FMD (Comb I vs. Statin: 16.4+/-4.7 vs. 7.9+/-4.7%, p < 0.01) and NMD (17.9+/-4.3 vs. 10.9+/-4.5%, p < 0.05) decreased significantly such that simvastatin alone only tended to improve FMD and did not change NMD. Results under combination therapy (Comb II vs. BL II) were reproducible. CONCLUSIONS: Combined vitamin E and simvastatin therapy leads to an improvement of FMD and NMD in the brachial artery of patients with hypercholesterolemia. The improvement of FMD is more pronounced after combination therapy than after lipid-lowering therapy alone, similar to previous findings in the coronary circulation.     

Biosynthesis of a cyclic tautomer of (3-methylmaleyl)acetone from 4-hydroxy-3,5-dimethylbenzoate by Pseudomonas sp. HH35 but not by Rhodococcus rhodochrous N75

Vitamin E is one of the most important lipid-soluble antioxidant nutrients. Severe vitamin E deficiency can have a profound effect on the central nervous system. Cystic fibrosis, chronic cholestatic liver disease, abetalipoproteinemia, short bowel syndrome, isolated vitamin E deficiency syndrome and other malabsorption syndromes all may cause varying degrees of neurologic deficits due to related vitamin deficiencies. The classic abnormalities in vitamin E deficiency progress from hyporeflexia, ataxia, limitations in upward gaze and strabismus to long-tract defects, profound muscle weakness and visual field constriction. Patients with severe, prolonged deficiency may develop complete blindness, dementia and cardiac arrhythmias. Treatment must be tailored to the underlying cause of vitamin E deficiency and may include oral or parenteral vitamin supplementation. The more advanced the deficits, the more limited the response to therapy. Therefore, a good neurologic examination and periodic serum vitamin E levels are essential in patients at risk of vitamin E deficiency.