Testosterone represses urinary excretion of the alpha-tocopherol metabolite alpha-carboxymethylhydroxychroman in rats

In rats, plasma and tissue concentrations of α-tocopherol, a predominant form of vitamin E in mammals, are known to differ between the sexes. In order to examine sex differences in α-tocopherol metabolism, we investigated urinary excretion of the α-tocopherol metabolite α-carboxymethylhydroxychroman (α-CEHC) using Wistar rats. First, we measured α-CEHC in urine of 9-week-old male and female rats in basal and α-tocopherol-administered conditions. We observed that female rats excrete significantly more α-CEHC than male rats via urine. This sex difference was observed in matured 9-week-old rats but not in premature 3-week-old rats, suggesting that the difference may relate to sex hormones. In order to confirm this, we examined the effect of ovariectomy and orchiectomy on female and male rats, respectively. The results of castration clearly demonstrated that orchiectomy enhanced urinary excretion of α-CEHC, supporting the hypothesis that testosterone repressed α-tocopherol metabolism. We then administered testosterone propionate to orchiectomized rats and observed down-regulation of α-CEHC excretion. Taken together, these results indicate that testosterone represses the metabolism and urinary excretion of α-tocopherol in rats. This is the first report to show a sex-dependent difference in urinary excretion rate of an α-tocopherol metabolite and contributes to the understanding of vitamin E metabolism.     

Effects of supplementation with vitamin E on the performance and the tissue peroxidation of broiler chicks and the stability of thigh meat against oxidative deterioration

Two experiments were conducted: Expt 1 determined the optimal allowance of vitamin E in the diet for broiler chicks aged 0–3 weeks; Expt 2 investigated the effects of different dietary levels of vitamin E (α-tocopherol) on the performance and the oxidative stability of thigh meat of broiler chicks during storage. In Expt 1, 1-day-old 900 broiler chicks were allocated to five treatments, each with six replicates (cages) of 22 as-hatched chicks for performance evaluation, and another cage of 45 male chicks for determining plasma and hepatic α-tocopherol and thiobarbituric acid reactive substances (TBARS) concentration in blood and liver. The basal dietary α-tocopherol concentration was 13 mg/kg, and the five α-tocopherol acetate supplementation levels were 0, 5, 10, 50 and 100 mg/kg. For 0–3-week-old broiler chicks fed with maize–soya bean meal–soya oil type diet, supplementation of vitamin E did not influence the feed intake, but tended to improve growth and feed utilization, however there was no significant correlation between performance and vitamin E supplementation level. Significant positive correlations existed between dietary supplemental vitamin E level and plasma or hepatic α-tocopherol concentrations (P<0.05), and a negative correlation with hepatic TBARS levels no matter at what age (11, 16 and 21 days). In Expt 2, 2200 broiler chicks were randomly allocated to five treatments with four replicates (pens) in each. Chicks were fed ad libitum five pellet diets supplemented with vitamin E at 5, 10, 20, 50 and 100 mg/kg of diet, respectively. The basal dietary α-tocopherol level of grower and finisher diets were 7 and 6 mg/kg, respectively. Supplementation of vitamin E tended to improve growth and feed utilization of birds during 0–3 weeks of age, but the performance from 0 to 6 weeks of age were not influenced. The hepatic α-tocopherol concentrations of 6-week-old chicks linearly increased with the dietary vitamin E levels (R²=0.98, P<0.001). The content of TBARS in the thigh meat over 4 days of storage under 4°C was significantly decreased by increasing dietary vitamin E level (P<0.05). There was a significant inverse relationship between TBARS value in the thigh meat and the dietary vitamin E level (R²=0.93, P<0.01). Supplementation of vitamin E significantly improved the meat quality stability substantially against oxidative deterioration. Comparing the hepatic α-tocopherol levels of chicks in Expts 1 and 2, total allowance of dietary α-tocopherol of 20–30 mg/kg could sustain relatively constant hepatic α-tocopherol level at round about 2–2.5 μg/kg.     

Short-term supplementation with flavanol-rich cocoa improves lipid profile,antioxidant status and positively influences the AA/EPA ratio in healthy subjects

We evaluated the short-term effects of a flavanol-rich cocoa (FRC) on lipid profile and selected oxidative stress biomarkers such as oxidized low-density lipoprotein (oxLDL), glutathione (GSH), and F₂-isoprostane. We also assessed whether FRC modulates plasma levels of polyunsaturated fatty acids (PUFA) in healthy individuals. The subjects (n=48) were randomly assigned to a low-cocoa group (1 g/d; ~55 mg flavanols) (n=16), middle-cocoa group (2 g/d; ~110 mg flavanols) (n=16), or a high-cocoa group (4 g/d; ~220 mg flavanols) (n=16). The samples were collected at baseline, at 1, 2, and 4 h post initial consumption of FRC, and after 4 weeks of FRC supplementation. The peak plasma concentration of (−)-epicatechin metabolites reached a maximum level (578±61 nM; P<.05) at 2 h after ingestion of FRC. After 4 weeks, total cholesterol (−12.37±6.63; P<.0001), triglycerides (−3.81±2.45; P<.0001), plasma LDL (−14.98±6.77; P<.0001), and oxLDL (−95.61±41.69; P<.0001) decreased in the high-cocoa group, compared with baseline. We also found that plasma high-density lipoprotein (HDL) (+3.37±2.06; P<.0001) concentrations increased significantly in the same group. Total GSH significantly increased in all FRC-treated groups (+209.73±146.8; P<.0001), while urinary F₂-isoprostane levels decreased in the middle- (−0.73±0.16; P<.0001) and high-cocoa (−1.62±0.61; P<.0001) groups. At the end of the four-week study, a significant reduction of arachidonic acid (AA)/eicosapentaenoic acid (EPA) ratio was observed in the low-(−2.62±2.93; P=.003), middle- (−5.24±2.75; P<.0001) and high-cocoa (−7.76±4.96; P<.0001) groups, compared with baseline. Despite the small sample size used in this study, these data extend previous clinical and experimental studies, providing new insights into the health benefits of cocoa flavanols.     

α-tocopherol β-oxidation localized to rat liver mitochondria

Approximately 40% of Americans take dietary supplements, including vitamin E (α-tocopherol). Unlike other fat-soluble vitamins, α-tocopherol is not accumulated to toxic levels. Rather tissue levels are tightly regulated, in part via increased hepatic metabolism and excretion that could, theoretically, alter metabolism of drugs, environmental toxins, and other nutrients. To date, in vivo subcellular location(s) of α-tocopherol metabolism have not been identified. The proposed pathway of α-tocopherol metabolism proceeds via ω-hydroxylation to 13′-OH-α-tocopherol, followed by successive rounds of β-oxidation to form α-CEHC. To test the hypothesis that α-tocopherol ω-hydroxylation occurs in microsomes while β-oxidation occurs in peroxisomes, rats received daily injections of vehicle, 10 mg α-tocopherol, or 10 mg trolox/100 g body wt for 3 days, and then microsomes, mitochondria, and peroxisomes were isolated from liver homogenates. Homogenate α-tocopherol levels increased 16-fold in α-tocopherol-injected rats, while remaining unchanged in trolox- or vehicle-injected rats. Total α-tocopherol recovered in the three subcellular fractions represented 93 ± 4% of homogenate α-tocopherol levels. In α-tocopherol-injected rats, microsome α-tocopherol levels increased 28-fold, while mitochondria and peroxisome levels increased 8- and 3-fold, respectively, indicating greater partitioning of α-tocopherol to the microsomes with increasing liver α-tocopherol. In α-tocopherol-injected rats, microsome 13′-OH-α-tocopherol levels increased 24-fold compared to controls, and were 7-fold greater than 13′-OH-α-tocopherol levels in peroxisome and mitochondrial fractions of α-tocopherol-injected rats. An unexpected finding was that α-CEHC, the end product of α-tocopherol metabolism, was found almost exclusively in mitochondria. These data are the first to indicate a mitochondrial role in α-tocopherol metabolism.     

Response to different sources of vitamin E orally injected and to various doses of vitamin E in calf starter on the plasma vitamin E level in calves around weaning

Calves often face a lower plasma vitamin E level than the recommended level (3 µg/ml for adult cows) after weaning, a level which has been related to a good immune response. Two experiments were performed to determine the most effective source and level of vitamin E to be included in a calf starter to maintain the plasma vitamin E level above the recommended level after weaning. Experiment 1 (Exp 1) and experiment 2 (Exp 2) included a total of 32 and 40 calves, respectively, from 2 weeks before weaning until 2 weeks after weaning. In Exp 1, calves were orally injected a daily dose of different vitamin E sources including, no α-tocopherol (0 dose; Control), 200 mg/d of RRR-α-tocopherol (ALC), 200 mg/d of RRR-α-tocopheryl acetate (ACT), or 200 mg/d of all-rac-α-tocopheryl acetate (SYN). In Exp 2, a dose response study was carried out with 0, 60, 120, and 200 mg/kg of ALC in a pelleted calf starter. Final BW (100 ± 16 and 86 ± 11 kg) and average daily gain (956 ± 303 and 839 ± 176 g/d in Exp 1 and 2, respectively; mean ± SD) were unaffected by either source or level of α-tocopherol. In Exp 1, the plasma RRR-α-tocopherol level was affected by α-tocopherol source (P < 0.001), week (P < 0.001), and interaction between them (P < 0.001). At weaning time, the plasma RRR-α-tocopherol was 2.7, 2.1, 1.1, and 0.8 μg/ml in ALC, ACT, SYN, and Control, respectively. In Exp 2, the plasma α-tocopherol level was affected by ALC dose (P = 0.04), week (P < 0.001), and a tendency for an interaction between them was observed (P = 0.06). At weaning, a 36, 31, and 28% reduction in plasma α-tocopherol level was observed compared to the beginning of the experiment with 0, 60, and 120 mg/kg of ALC, respectively; however, with 200 mg/kg of ALC, a 9% increase in the plasma α-tocopherol level was observed. In addition, 200 mg/kg of ALC was able to maintain plasma α-tocopherol after weaning higher than the recommended level. The results showed that the ALC was the most efficient source of α-tocopherol supplementation to be used in a calf starter. In addition, the 200 mg/kg of ALC in the calf starter was the only effective dose to maintain the postweaning plasma vitamin E concentration at the recommended level after weaning and α-tocopherol similar to that observed before weaning.     

α-Tocopherol injections in rats up-regulate hepatic ABC transporters, but not cytochrome P450 enzymes

The role of hepatic xenobiotic regulatory mechanisms in modulating hepatic α-tocopherol concentrations during excess vitamin E administration remains unclear. We hypothesized that increased hepatic α-tocopherol would cause a marked xenobiotic response. Thus, we assessed cytochrome P450 oxidation systems (phase I), conjugation systems (phase II), and transporters (phase III) after daily α-tocopherol injections (100mg/kg body wt) for up to 9days in rats. α-Tocopherol injections increased hepatic α-tocopherol concentrations nearly 20-fold, along with a 10-fold increase in the hepatic α-tocopherol metabolites α-CEHC and α-CMBHC. Expression of phase I (CYP3A2, CYP3A1, CYP2B2) and phase II (SULT2A1) proteins and/or mRNAs was variably affected by α-tocopherol injections; however, expression of phase III transporter genes was consistently changed by α-tocopherol. Two liver efflux transporter genes, ABCB1b and ABCG2, were up-regulated after α-tocopherol injections, whereas OATP, a liver influx transporter, was down-regulated. Thus, an overload of hepatic α-tocopherol increases its own metabolism and increases expression of genes of transporters that are postulated to lead to increased excretion of both vitamin E and its metabolites.     

Supplementation of Merino ewes with vitamin E plus selenium increases α-tocopherol and selenium concentrations in plasma of the lamb but does not improve their immune function

Vitamin E and selenium have been reported to improve immune function across a range of species. Ewes lambing on poor-quality dry pasture in autumn in Western Australia are at risk of being deficient in vitamin E and selenium at lambing thus predisposing their lambs to deficiencies and increasing the risk of infection and disease. This study tested the hypotheses that (i) supplementation of autumn-lambing ewes with vitamin E plus selenium in late gestation will increase the concentrations of vitamin E and selenium in plasma in the ewe and lamb and (ii) that the increased concentrations of vitamin E and selenium in plasma in the lambs will improve their innate and adaptive immune responses and thus survival. Pregnant Merino ewes were divided into a control group (n=58) which received no supplementation or a group supplemented with vitamin E plus selenium (n=55). On days 111, 125 and 140 of pregnancy ewes in the vitamin E plus selenium group were given 4 g all-rac-α-tocopherol acetate orally. On day 111 the ewes were also given 60 mg of selenium as barium selenate by subcutaneous injection. The concentrations of α-tocopherol and selenium were measured in ewes and/or lambs from day 111 of pregnancy to 14 weeks of age±10 days (weaning). Immune function of the lamb was assessed by analysing the numbers and phagocytic capacities of monocytes and polymorphonuclear leucocytes and plasma IgG and anti-tetanus toxoid antibody concentrations between birth and 14 weeks of age±10 days. Maternal supplementation with vitamin E plus selenium increased the concentration of α-tocopherol in plasma (1.13 v. 0.67 mg/l; P<0.001) and selenium in whole blood (0.12 v. 0.07 mg/l; P<0.01) of the ewes at lambing compared with controls. Supplementation also increased the concentration of α-tocopherol (0.14 v. 0.08 mg/l; P<0.001) and selenium (0.08 v. 0.05 mg/l; P<0.01) in lambs at birth compared with controls. There was no significant effect of supplementation on immune function or survival in the lambs.     

Association between the plasma proteome and plasma α-tocopherol concentrations in humans

Vitamin E is a lipophilic antioxidant that has been inversely associated with certain chronic diseases; however, the biological processes regulated by this vitamin have not been fully elucidated. The objective of the present study was to examine the association between the most biologically active and abundant form of vitamin E in the circulation, α-tocopherol, and the plasma proteome. Subjects were from the Toronto Nutrigenomics and Health Study and included men and women (n=1,022) who completed a general health and lifestyle questionnaire and 196-item food frequency questionnaire, and provided a fasting blood sample. Plasma α-tocopherol concentrations were measured by high-performance liquid chromatography and 54 plasma proteins were assayed by a mass spectrometry-based multiple reaction monitoring method. Analysis of covariance was used to compare mean concentrations of plasma proteins across tertiles of α-tocopherol. Plasma concentrations of apolipoprotein C-III, fibrinogen alpha, beta, and gamma chains, fibronectin and fibrinopeptide A were significantly and positively associated with plasma α-tocopherol, while intermediate levels of α-tocopherol were significantly associated with higher levels of alpha-1B-glycoprotein (all P<.0009). These findings show that circulating levels of α-tocopherol are significantly associated with specific plasma proteins and suggest novel physiological effects of vitamin E.     

Plasma tocopherol,retinol, and carotenoid concentrations in free-ranging Humboldt penguins (Spheniscus humboldti) in Chile

Plasma retinol and α-tocopherol concentrations were measured in heparinized blood samples collected from 51 free-ranging adult Humboldt penguins (Sphenicus humboldti) residing at two colonies off the Chilean coast. Thirty samples were collected in April 1992 from penguins inhabiting the Ex-islote de los Pájaros Niños in Algarrobo, Chile. In September 1992, 21 samples were collected from birds inhabiting Isla de Cachagua, Chile. Samples were assayed for retinol, retinyl palmitate, α-tocopherol, γ-tocopherol, lutein, β-cryptoxanthin, lycopene, α-carotene, and β-carotene. Retinol, α-tocopherol, and lutein were detected in all samples, while lycopene and γ-tocopherol were not detected in any. A significantly higher percentage of samples had detectable levels of retinyl palmitate and α-carotene in April (P < 0.001): for β-cryptoxanthin the percentage was higher in September (P < 0.001). Plasma concentrations of α-tocopherol and lutein were higher in September. Alpha-tocopherol concentrations were 1,877.1 ± 99.0 (SEM) μg/dl in April compared to 2.289 ± 122.3 μg/dl in September (P < 0.05); lutein concentrations were 4.16 ± 0.43 μg/dl in April vs. 10.68 ± 1.02 μg/dl in September (P < 0.001). Retinol concentrations were not significantly different (117 ± 8.0 μg/dl in April vs. 105.3 ± 7.6 μg/dl in September). Both physiologic changes associated with season, and the change in locale may have contributed to the differences seen in the assay means and the number of samples with detectable levels. © 1996 Wiley-Liss, Inc.     

Photochemiluminescent detection of antiradical activity; IV: testing of lipid-soluble antioxidants

A new method for quantification of antiradical properties of pure lipid-soluble antioxidants and for measurement of integral antioxidant capacity in the lipid phase (ACL) of polycomponent systems, such as blood plasma or tissue homogenates, is developed. It is based on an antioxidant-sensitive inhibition of a photo-induced, chemiluminescence accompanied autoxidation of luminol. The sensitivity of the photochemiluminescent (PCL) assay lies within nmol quantities of substances, the measuring range for α-tocopherol is between 0.1 and 3 nmol. The interassay variability of the method is lower than 5%, the intraassay variability <2%. The antioxidant efficiency of γ-tocopherol was found to be 43% of α-tocopherol. The results of the PCL measurements on pure antioxidants and on lipid extracts from blood plasma were compared with the level of, ‘vitamin E’ (VE) determined as a sum of α- and γ-tocopherol by HPLC. Very good coincidence of both methods was observed for pure substances (r = 0.998, P<0.001). The ACL of human blood plasma was found to be 27.98 ± 0.68 μmol equivalents of α-tocopherol/l (mean ± mean error, n = 142), it is ∼ 25% more than the concentration of VE found in the same samples (22.09 ± 0.59 μmol/l). In this case, the correlation of both parameters was lower: r = 0.811, P<0.001. The animal experiments showed that synthetic antioxidants may not only increase the value of ACL of blood plasma but in the same time reduce the concentration of biological antioxidants, e.g. VE drastically. The prooxidant activity of synthetic antioxidants in vivo or the replacing of structured α-tocopherol from its position can be the cause. This important circumstance has to be considered during the testing of new antioxidants for clinical application.     

EFFECT OF VITAMIN E SUPPLEMENTATION AND PARTIAL SUBSTITUTION OF POLY- WITH MONO-UNSATURATED FATTY ACIDS IN PIG DIETS ON MUSCLE,AND MICROSOME EXTRACT a-TOCOPHEROL CONCENTRATION AND LIPID OXIDATION

The experiment was organized in a 3×2 factorial arrangement with three dietary fat blends and a basal (20 mg kg^?1 diet) or supplemented (220 mg kg^?1) level of α-tocopheryl acetate. Dietary vitamin E and monounsaturated to polyunsaturated fatty acid ratio (dietary MUFA/PUFA) affected muscle α-tocopherol concentration (α-tocopherol [log μg g^?1]=0.18 (±0.105)+0.0034 (±0.0003)·dietary α-tocopherol [mg kg^?1 diet] (P<0.0001)+0.39 (±0.122)·dietary MUFA/PUFA (P<0.0036)). An interaction between dietary α-tocopherol and dietary MUFA/PUFA exists for microsome α-tocopherol concentration (α-tocopherol [log μg g^?1]=1.14 (±0.169) (P<0.0001)+0.0056 (±0.00099)·dietary α-tocopherol [mg kg^?1 diet] (P<0.0001)+0.54 (±0.206)·dietary MUFA/PUFA (P<0.0131)?0.0033 (±0.0011)·dietary α-tocopherol [mg kg^?1)]×dietary MUFA/PUFA (P<0.0067)), and hexanal concentration in meat (hexanal [ng·g^?1]=14807.9 (±1489.8)?28.8 (±10.6) dietary α-tocopherol [mg·kg^?1] (P<0.01)?8436.6 (±1701.6)·dietary MUFA/PUFA (P<0.001)+24.0 (±11.22)·dietary α-tocopherol·dietary MUFA/PUFA (P<0.0416)). It is concluded that partial substitution of dietary PUFA with MUFA lead to an increase in the concentration of α-tocopherol in muscle and microsome extracts. An interaction between dietary α-tocopherol and fatty acids exists, in which at low level of dietary vitamin E inclusion, a low MUFA/PUFA ratio leads to a reduction in the concentration of α-tocopherol in microsome extracts and a concentration of hexanal in meat above the expected values.     

Nonalcoholic fatty liver disease impairs the cytochrome P-450-dependent metabolism of α-tocopherol (vitamin E)

This study aims to investigate in in vivo and in vitro models of nonalcoholic fatty liver disease (NAFLD) the enzymatic metabolism of α-tocopherol (vitamin E) and its relationship to vitamin E-responsive genes with key role in the lipid metabolism and detoxification of the liver. The experimental models included mice fed a high-fat diet combined or not with fructose (HFD+F) and HepG2 human hepatocarcinoma cells treated with the lipogenic agents palmitate, oleate or fructose. CYP4F2 protein, a cytochrome P-450 isoform with proposed α-tocopherol ω-hydroxylase activity, decreased in HFD and even more in HFD+F mice liver; this finding was associated with increased hepatic levels of α-tocopherol and decreased formation of the corresponding long-chain metabolites α-13-hydroxy and α-13-carboxy chromanols. A decreased expression was also observed for PPAR-γ and SREBP-1 proteins, two vitamin E-responsive genes with key role in lipid metabolism and CYP4F2 gene regulation. A transient activation of CYP4F2 gene followed by a repression response was observed in HepG2 cells during the exposure to increasing levels of the lipogenic and cytotoxic agent palmitic acid; such gene repression effect was further exacerbated by the co-treatment with oleic acid and α-tocopherol and was also observed for PPAR-γ and the SREBP isoforms 1 and 2. Such gene response was associated with increased uptake and ω-hydroxylation of α-tocopherol, which suggests a minor role of CYP4F2 in the enzymatic metabolism of vitamin E in HepG2 cells. In conclusion, the liver metabolism and gene response of α-tocopherol are impaired in experimental NAFLD.     

Dietary α- and γ-tocopherol supplementation attenuates lipopolysaccharide-induced oxidative stress and inflammatory-related responses in an obese mouse model of nonalcoholic steatohepatitis

Oxidative stress contributes towards the development of nonalcoholic steatohepatitis (NASH). Thus, antioxidants may decrease oxidative stress and ameliorate the events contributing to NASH. We hypothesized that α- or γ-tocopherol would protect against lipopolysaccharide (LPS)-triggered NASH in an obese (ob/ob) mouse model. Five-week-old obese mice (n=18/dietary treatment) were provided 15 mg/kg each of α- and γ-tocopherol or 500 mg/kg of α- or γ-tocopherol for 5-weeks. Then, all mice were injected ip once with LPS (250 μg/kg) before being sacrificed at 0, 1.5 or 6 h. Body weight and hepatic steatosis were unaffected by tocopherols and LPS. Hepatic α- and γ-tocopherol increased (P<.05) ~9.8- and 10-fold in respective tocopherol supplemented mice and decreased in response to LPS. LPS increased serum alanine aminotransferase (ALT) by 86% at 6 h and each tocopherol decreased this response by 29–31%. By 6 h, LPS increased hepatic malondialdehyde (MDA) and tumor necrosis factor-α by 81% and 44%, respectively, which were decreased by α- or γ-tocopherol. Serum ALT was correlated (P<.05) to hepatic tumor necrosis factor-α (r=0.585) and MDA (r=0.592), suggesting that inflammation and lipid peroxidation contributed to LPS-triggered hepatic injury. α- and γ-Tocopherol similarly attenuated LPS-triggered increases in serum free fatty acid, and α-tocopherol only maintained the LPS-triggered serum triacylglycerol responses at 6 h. These findings indicate that increasing hepatic α- or γ-tocopherol protected against LPS-induced NASH by decreasing liver damage, lipid peroxidation, and inflammation without affecting body mass or hepatic steatosis. Further study is needed to define the mechanisms by which these tocopherols protected against LPS-triggered NASH.     

Oral a-tocopherol Supplementation Inhibits Lipid Oxidation in Established Human Atherosclerotic Lesions

Background: Much experimental evidence suggests that lipid oxidation is important in atherogenesis and in epidemiological studies dietary antioxidants appear protective against cardiovascular events. However, most large clinical trials failed to demonstrate benefit of oral antioxidant vitamin supplementation in high-risk subjects. This paradox questions whether ingestion of antioxidant vitamins significantly affects lipid oxidation within established atherosclerotic lesions. Methods and results: This placebo-controlled, double blind study of 104 carotid endarterectomy patients determined the effects of short-term α-tocopherol supplementation (500 IU/day) on lipid oxidation in plasma and advanced atherosclerotic lesions. In the 53 patients who received α-tocopherol there was a significant increase in plasma α-tocopherol concentrations (from 32.66±13.11 at baseline to 38.31±13.87 (mean±SD) μmol/l, p&lt;0.01), a 40% increase (compared with placebo patients) in circulating LDL-associated α-tocopherol (p&lt;0.0001), and their LDL was less susceptible to ex vivo oxidation than that of the placebo group (lag phase 115.3±28.2 and 104.4±15.7 min respectively, p&lt;0.02). Although the mean cholesterol-standardised α-tocopherol concentration within lesions did not increase, α-tocopherol concentrations in lesions correlated significantly with those in plasma, suggesting that plasma α-tocopherol levels can influence lesion levels. There was a significant inverse correlation in lesions between cholesterol-standardised levels of α-tocopherol and 7β-hydroxycholesterol, a free radical oxidation product of cholesterol. Conclusions: These results suggest that within plasma and lesions α-tocopherol can act as an antioxidant. They may also explain why studies using &lt;500 IU α-tocopherol/day failed to demonstrate benefit of antioxidant therapy. Better understanding of the pharmacodynamics of oral antioxidants is required to guide future clinical trials.     

High-energy breakfast based on whey protein reduces body weight,postprandial glycemia and HbA1C in Type 2 diabetes

Acute studies show that addition of whey protein at breakfast has a glucose-lowering effect through increased incretin and insulin secretion. However, whether this is a long-term effect in Type 2 diabetes is unknown. Fifty-six Type 2 diabetes participants aged 58.9±4.5 years, BMI 32.1±0.9 kg/m² and HbA_1C 7.8±0.1% (61.6±0.79 mmol/mol) were randomized to one of 3 isocaloric diets with similar lunch and dinner, but different breakfast: 1) 42 g total protein, 28 g whey (WBdiet, n=19); 2) 42 g various protein sources (PBdiet, n=19); or 3) high-carbohydrate breakfast, 17 g protein from various sources (CBdiet, n=18). Body weight and HbA_1C were examined after 12 weeks. All participants underwent three all-day meal challenges for postprandial glycemia, insulin, C-peptide, intact glucagon-like peptide 1 (iGLP-1), ghrelin and hunger and satiety scores. Overall postprandial AUC_glucose was reduced by 12% in PBdiet and by 19% in WBdiet, compared with CBdiet (P<.0001). Compared with PBdiet and CBdiet, WBdiet led to a greater postprandial overall AUC for insulin, C-peptide, iGLP-1 and satiety scores, while postprandial overall AUC for ghrelin and hunger scores were reduced (P<.0001). After 12 weeks, HbA_1C was reduced after WBdiet by 0.89±0.05% (11.5±0.6 mmol/mol), after PBdiet by 0.6±0.04% (7.1±0.31 mmol/mol) and after CBdiet by 0.36±0.04% (2.9±0.31 mmol/mol) (P<.0001). Furthermore, the participants on WBdiet lost 7.6±0.3 kg, PBdiet 6.1±0.3 kg and CBdiet 3.5±0.3 kg (P<.0001). Whey protein-based breakfast is an important adjuvant in the management of Type 2 diabetes.     

Vitamin E attenuates acute lung injury in sheep with burn and smoke inhalation injury

Abstract

Introduction: A decrease in α-tocopherol (vitamin E) plasma levels in burn patients is typically associated with increased mortality. We hypothesized that vitamin E supplementation (α-tocopherol) would attenuate acute lung injury induced by burn and smoke inhalation injury.

Materials and Methods: Under deep anesthesia, sheep (33 ± 5 kg) were subjected to a flame burn (40% total body surface area, third degree) and inhalation injury (48 breaths of cotton smoke, < 40°C). Half of the injured group received α-tocopherol (1000 IU vitamin E) orally, 24 h prior to injury. The sham group was neither injured nor given vitamin E. All three groups (n = 5 per group) were resuscitated with Ringer's lactate solution (4 ml/kg/%burn/24 h), and placed on a ventilator (PEEP = 5 cmH₂O; tidal volume = 15 ml/kg) for 48 h.

Results: Plasma α-tocopherol per lipids doubled in the vitamin E treated sheep. Vitamin E treatment prior to injury largely prevented the increase in pulmonary permeability index and moderated the increase in lung lymph flow (52.6 ± 6.2 ml/min, compared with 27.3 ± 6.0 ml/min, respectively), increased the PaO₂/FiO₂ ratio, ameliorated both peak and pause airway pressure increases, and decreased plasma conjugated dienes and nitrotyrosine.

Conclusions: Pretreatment with vitamin E ameliorated the acute lung injury caused by burn and smoke inhalation exposure.     

Vitamin A metabolism: α-Tocopherol modulates tissue retinol levels in vivo,and retinyl palmitate hydrolysis in vitro

The steady-state concentrations of retinol in rat tissues varied as a function of dietary α-tocopherol. The liver, kidney, and intestinal retinol concentrations increased in animals fed an α-tocopherol-deficient diet despite a decrease (liver) or no change (kidney and intestine) in the concentrations of total vitamin A. In contrast, in lung the concentrations of both retinol and total vitamin A decreased. α-Tocopherol inhibited retinyl palmitate hydrolase in vitro in liver, kidney, and intestine; had minimal effect on the testes hydrolase; and stimulated the lung hydrolase. Fifty percent inhibition of the liver hydrolase was provided by an α-tocopherol concentration (100 μm), close to that reported in livers of rats fed a purified diet, constituted with moderately low amounts of α-tocopheryl acetate. Phylloquinone (vitamin K₁) inhibited the retinyl palmitate hydrolase in vitro in all tissues tested, and was about fivefold more potent than α-tocopherol. The effects of phylloquinone and α-tocopherol on the liver hydrolase were additive, not synergistic. The antioxidant N,N′-diphenyl-p-phenylenediamine, the most effective synthetic vitamin E substitute known, had little effect on the hydrolase. These data show that α-tocopherol effects vitamin A metabolism in several tissues, and suggest that it may be a physiological effector of tissue retinol homeostasis.     

Solid Phase Synthesis of Mitochondrial Triphenylphosphonium-Vitamin E Metabolite Using a Lysine Linker for Reversal of Oxidative Stress

Mitochondrial targeting of antioxidants has been an area of interest due to the mitochondria''s role in producing and metabolizing reactive oxygen species. Antioxidants, especially vitamin E (α-tocopherol), have been conjugated to lipophilic cations to increase their mitochondrial targeting. Synthetic vitamin E analogues have also been produced as an alternative to α-tocopherol. In this paper, we investigated the mitochondrial targeting of a vitamin E metabolite, 2,5,7,8-tetramethyl-2-(2′-carboxyethyl)-6-hydroxychroman (α-CEHC), which is similar in structure to vitamin E analogues. We report a fast and efficient method to conjugate the water-soluble metabolite, α-CEHC, to triphenylphosphonium cation via a lysine linker using solid phase synthesis. The efficacy of the final product (MitoCEHC) to lower oxidative stress was tested in bovine aortic endothelial cells. In addition the ability of MitoCEHC to target the mitochondria was examined in type 2 diabetes db/db mice. The results showed mitochondrial accumulation in vivo and oxidative stress decrease in vitro.     

a-Tocopherol Content and a-Tocopherol Transfer Protein Expression in Leukocytes of Children with Acute Leukemia

α-Tocopherol (a form of vitamin E) is a fat-soluble vitamin that can prevent lipid peroxidation of cell membranes. This antioxidant activity of α-tocopherol can help to prevent cardiovascular disease, atherosclerosis and cancer. We investigated the α-tocopherol level and the expression of α-tocopherol transfer protein (α-TTP) in the leukocytes of children with leukemia. The plasma and erythrocyte α-tocopherol levels did not differ between children with leukemia and the control group. However, lymphocytes from children with leukemia had significantly lower α-tocopherol levels than lymphocytes from the controls (58.4±39.0 ng/mg protein versus 188.9±133.6, respectively; p&lt;0.05), despite the higher plasma α-tocopherol/cholesterol ratio in the leukemia group (5.83±1.64 μmol/mmol versus 4.34±0.96, respectively; p&lt;0.05). No significant differences in the plasma and leukocyte levels of isoprostanes (the oxidative metabolites of arachidonic acid) were seen between the leukemia patients and controls. The plasma level of acrolein, a marker of oxidative stress, was also similar in the two groups. Investigation of α-TTP expression by leukocytes using real-time PCR showed no difference between the two groups. These findings suggest that there may be comparable levels of lipid peroxidation in children with untreated leukemia and controls, despite the reduced α-tocopherol level in leukemic leukocytes.     

Excimer laser coronary angioplasty and intracoronary radiation for in-stent restenosis: Six-month angiographic and clinical outcomes

Background: The purpose of this study was to evaluate 6-month clinical and angiographic outcomes in patients treated with excimer laser coronary angioplasty (ELCA) and intracoronary radiation (ICR) for in-stent restenosis (ISR).Methods: A consecutive series of 175 patients with ISR treated with ELCA+ICR (gamma and beta emitters) were compared to 33 patients with ISR treated with ELCA alone. Baseline characteristics were similar between groups. ELCA+ICR and ELCA-alone patients had similar lesion lengths (25.0±12.0 vs. 24.0±16.8 mm, P=NS) in predominantly saphenous vein grafts (SVG, 38% vs. 42%, P=NS).Results: Procedural success was high (ELCA+ICR, 97.0% vs. ELCA alone, 98.5%, P=NS), with no perforations or acute vessel closures. ELCA+ICR therapy reduced target vessel revascularization (TVR; 27% vs. 64%, P<.0001) and major adverse cardiac events [MACE: death, myocardial infarction (MI), or TVR; 30% vs. 64%, P<.0001] compared to ELCA alone. Late loss was 0.66±0.90 mm in ELCA+ICR patients and 0.85±0.60 mm in ELCA-alone patients (P=NS). Angiographic binary restenosis (>50%) was significantly reduced with adjunctive ICR (28% vs. 54%, P=.014).Conclusion: Radiation therapy with ELCA significantly reduces angiographic binary restenosis at 6 months in patients with diffuse ISR, driven predominantly by reduced percutaneous TVR.