Dietary vitamin E prophylaxis and diabetic embryopathy: morphologic and biochemical analysis

OBJECTIVE

In this study we sought to determine whether dietary supplementation with vitamin E, a known antioxidant, would reduce the incidence of diabetic embryopathy in an in vivo rat model.

STUDY DESIGN

Eighty-day-old Sprague-Dawley rats were assigned to one of five groups: two control groups (groups 1 and 2) and three diabetic groups (groups 3, 4, and 5). One group of controls (group 2) and one group of diabetic rats (group 4) received dietary supplements of vitamin E (440 mg/day). The other three groups (groups 1, 3, and 5) received a normal diet only. Group 5 received insulin therapy to control glucose levels. On day 6 of gestation diabetes was induced in groups 3, 4, and 5 with streptozotocin (65 mg/kg). Animals were killed on day 12; embryos were examined for size, protein content, evidence of malformations, and superoxide dismutase activity.

RESULTS

In both groups (groups 3 and 4) of diabetic rats the mean blood glucose level than was significantly higher in controls. Insulin-treated animals (group 5) had glucose levels that were comparable to those of controls. The unsupplemented diabetic group had a neural tube defect rate of 21.48% +/- 9.6% (percentage of neural tube defects per rat) and a resorption rate of 21.37% +/- 20.39% (percentage of resorptions per rat) as compared with rates in the supplemented diabetic group of 6.92% +/- 4.08% and 2.17% +/- 3.74%, respectively (p < 0.01). Groups 1, 2, and 5 had similar neural tube defect rates (6.63% +/- 5.0%, 5.01% +/- 4.87%, and 3.55% +/- 5.92%, respectively. Vitamin E levels, measured by high-performance liquid chromatography, were significantly higher in maternal serum and embryos in the supplemented groups (p < 0.001) than in controls. Superoxide dismutase activity was reduced in the diabetes groups and was not affected by vitamin E therapy.

CONCLUSIONS

Supplementation with the antioxidant vitamin E confers a significant protective effect against diabetic embryopathy and may potentially serve as a dietary prophylaxis in the future. We postulate that this protective effect is mediated by a reduction in the oxidative load induced by hyperglycemia.

Alpha-tocopherol in the ventricular cerebrospinal fluid of Parkinson's disease patients: dose-response study and correlations with plasma levels

OBJECTIVE

To determine if ventricular cerebrospinal fluid (vCSF) alpha-tocopherol levels in Parkinson's disease (PD) patients can be increased by oral alpha-tocopherol supplementation and whether vCSF levels are linearly related to plasma alpha-tocopherol levels.

BACKGROUND

In spite of its putative neuroprotective properties, alpha-tocopherol has failed to alter PD clinical progression. However, the ability of supplemental alpha-tocopherol to affect brain or vCSF levels has never been assessed in humans nor has a dose response curve for alpha-tocopherol in vCSF been established.

METHODS

Five PD patients with Ommaya catheters received oral dl-alpha-tocopherol over 5 months. Each patient ingested alpha-tocopherol daily with monthly dosage increases (400, 800, 1,600, 3,200, 4,000 IU/day). Plasma and vCSF samples were obtained at baseline and at the end of each month. Alpha-tocopherol levels were determined in triplicate by high-pressure liquid chromatography with fluorometric and electrochemical detection.

RESULTS

At baseline, endogenous alpha-tocopherol was detected in plasma and vCSF, with a greater than one-hundred-fold difference between the fluid compartments (mean plasma level 18.76 microM/l (SD +/- 4.69) versus mean CSF level 0.114 microM/l (SD +/- 0.084). A clear dose-response curve occurred in plasma, with statistically significant increases over baseline developing even with 400 IU/d. With higher doses, a significant increase continued without evidence of saturation. However, there was no significant increase in vCSF alpha-tocopherol levels at any dose, including the supraclinical (4,000 IU/d). There was no correlation between plasma and vCSF alpha-tocopherol levels.

CONCLUSION

Oral alpha-tocopherol supplementation, even at supraclinical doses, fails to increase vCSF alpha-tocopherol levels. This lack of change may be due to limited passage across the blood-brain barrier or very rapid alpha-tocopherol metabolism. All prior negative studies on efficacy of alpha-tocopherol in PD may need reevaluation in light of these pharmacologic data.

Anti-oxidant treatment for shock: vitamin E but not vitamin C improves survival

Anti-oxidant therapy has been effective for treatment of experimental shock. In this study, the efficacy of Trolox (Aldrich Chemical Co., Milwaukee, WI), a water-soluble vitamin E analogue, and ascorbic acid (vitamin C) was evaluated in a rat model of hemorrhagic shock and resuscitation. In two prospective trials, rats were phlebotomized (27 mL/kg) and left in shock for 45 minutes. Resuscitation was then instituted by continuous IV infusion with lactated Ringer's (LR) (54 mL/kg) over 60 min. In Trial 1, rats were randomized to receive either placebo (LR) or Trolox (50 mg/kg) in LR. In Trial 2, rats were randomized to LR alone or ascorbic acid (50 mg/kg) in LR. Survival for ascorbic acid-treated rats (35 per cent) was not different than for control rats (35 per cent). However, the addition of Trolox to infusion significantly improved 72 hour survival, 75 per cent versus 40 per cent respectively, for Trolox-treated and control animals. These data demonstrate that Trolox is of survival benefit when added to resuscitation in this model. This benefit does not appear to be related to blood pressure or white cell adhesion. Trolox is more effective than ascorbic acid in this model.

Effect of alpha-tocopherol on isoproterenol induced myocardial infarction in rats--electrocardiographic biochemical and histological evidences

The effect of alpha-tocopherol (6 mg/100 g body wt, orally, daily for 90 days) pretreatment in isoproterenol (20 mg/100 g body wt, subcutaneously, twice at an interval of two days at the end of the alpha-tocopherol pretreatment) induced myocardial infarction was studied in rats. Isoproterenol administered rats showed electrocardiographic changes suggestive of myocardial infarction with marked ST segment elevation, Q waves appearance and a significant increase in heart rate. In isoproterenol administered rats, a significant decrease was observed in the activities of marker enzymes such as aspartate amino transferase, alanine amino transferase, lactate dehydrogenase and creatine kinase in heart and aorta with a significant increase in their activities in serum. The levels of lipid peroxides in terms of "TBA reactants" increased significantly in serum, heart and aorta on isoproterenol administration. The histology of heart and aorta showed marked fragmentation of muscle fibres and necrotic lesions in isoproterenol administered rats. alpha-Tocopherol pretreated rats showed a near normal ECG pattern, levels of lipid peroxides, activities of marker enzymes and a near normal histology of heart and aorta on isoproterenol administration.

Effect of modest vitamin E supplementation on blood glycated hemoglobin and triglyceride levels and red cell indices in type I diabetic patients

OBJECTIVE

The glycation of proteins and elevated triglyceride (TG) levels are two of the major risk factors in the development of complications of diabetes. Previous studies have found some beneficial effects of supplementation of pharmacological doses (900-2000 IU/day) of vitamin E in Type II diabetic patients. This study examined whether supplementation with a modest dose of vitamin E (100 IU/day) had any effect on blood glucose, glycated hemoglobin (GHb), TG or red cell counts in Type I diabetic patients.

METHODS

35 diabetic patients were supplemented with either DL-alpha-tocopherol (vitamin E) capsules (orally, 100 IU/day) or a placebo for 3 months in a double-blind clinical trial. Fasting blood was collected from each diabetic patient before and after vitamin E or placebo supplementation. Data were analyzed using paired "t" tests and the Wilcoxon Signed Rank Test.

RESULTS

Levels of GHb (mean +/- SEM) were 11.5 +/- 0.4 and 12.8 +/- 0.9% (p < 0.05); glucose, 8.8 +/- 1.2 and 11.6 +/- 1.3 mM; and TG, 2.2 +/- 0.2 and 2.9 +/- 0.3 mM (p < 0.03) after vitamin E supplementation versus before supplementation. There were no differences in these parameters after supplementation with the placebo. There was no effect on blood RBC, hematocrit, and hemoglobin levels after supplementation of vitamin E or the placebo. There were no differences in ages and duration of diabetes between placebo and vitamin E-supplemented groups.

CONCLUSIONS

This study suggests that modest vitamin E supplementation (100 IU/day) can significantly lower blood GHb and TG levels and does not have any effect on red cell indices in Type I diabetic patients.

Effects of vitamin E on endothelium-dependent coronary flow in hypercholesterolemic dogs

The authors studied the effect of vitamin E on endothelium-dependent coronary flow in hypercholesterolemic dogs. Adult mongrel dogs weighing 7.4 +/- 1.0 kg were divided into control, hypercholesterolemic and vitamin E groups. The animals in the hypercholesterolemic group were fed a diet enriched with cholesterol (5% w/w) and coconut oil (10% w/w) for 40 days. The vitamin E group received the same diet plus 400 IU of vitamin E during the last 15 days of the experiment. Total serum cholesterol levels were evaluated at the beginning and at the end of the experiment using a commercial enzyme kit and a Beckman analyzer. The coronary flow was determined by electromagnetic flowmetry using a probe positioned in the left anterior descending coronary artery, near the ostium. A needle connected to a perfusion pump was introduced into the coronary artery for the administration of acetylcholine and sodium nitroprusside at a rate of 5 micrograms/kg per min. The aorta was cannulated for the measurement of arterial blood pressure via a pressure transducer coupled to a Siemens multi-channel recorder. The tissue cholesterol content and malonic dialdehyde (MDA) were also measured in isolated coronary vessel specimens. At the end of 40 days, the serum cholesterol levels had increased by 226% and 190% in the hypercholesterolemic and vitamin E groups, respectively. However, the difference in the levels of these two groups was not significant (P > 0.05). The aortic blood pressure and heart rate remained unchanged during acetylcholine administration. In contrast, systolic and diastolic pressure fell and the heart rate increased during the infusion of sodium nitroprusside. The tissue cholesterol content and MDA were significantly (P < 0.05) increased in coronary artery specimens from the hypercholesterolemic compared to control animals. Vitamin E was able to reduce these increases in cholesterol treated animals (P < 0.05). The percent change in coronary flow during acetylcholine administration was significantly lower in the hypercholesterolemic group when compared with control animals (P < 0.05) but was unaltered in the vitamin E group (P > 0.05). During sodium nitroprusside administration, the coronary flow increased in the vitamin E group (P < 0.05). The authors conclude that hypercholesterolemia reduces endothelium-dependent coronary flow and increases the tissue cholesterol content and MDA of coronary arteries. Vitamin E decreases the MDA and the tissue cholesterol content without significantly affecting the total serum cholesterol level. Vitamin E may thus restore coronary flow by reverting endothelial dysfunction.

Isolated vitamin E deficiency

A 22-year-old man presented with progressive gait instability, tremor, and dysarthria since childhood. Electrophysiologic studies revealed a sensorimotor polyneuropathy. Laboratory studies documented vitamin E deficiency; however, no gastrointestinal, hepatic, or lipoprotein disorder could be identified. Vitamin E therapy normalized the serum level, but there was no neurologic improvement. Isolated vitamin E deficiency, in the absence of lipid malabsorption, should be considered in the evaluation of children and adults with ataxia and peripheral neuropathy.

Wheat kernel ingestion protects from progression of muscle weakness in mdx mice, an animal model of Duchenne muscular dystrophy

A simple, reproducible test was used to quantify muscle weakness in mdx mice, an animal model of Duchenne muscular dystrophy. The effect of bedding on wheat kernels and of dietary supplementation of alpha-tocopherol on the progression of muscle weakness was investigated in mdx mice. When measured during the first 200 d of life, mdx mice developed muscle weakness, irrespective of bedding and diet. When kept on wood shavings and fed a conventional rodent diet, mdx mice showed progressive muscle weakness over the consecutive 200 d, and eventually showed a significant weight loss during the next 200-d observation period. Progression of muscle weakness and weight loss were almost completely prevented in mdx mice that were kept on wheat kernel bedding. In contrast, only incomplete maintenance of muscle strength and body weight was observed in mdx mice kept on wood shavings and fed the alpha-tocopherol-supplemented diet. It is concluded from these experiments that a component of wheat kernels other than alpha-tocopherol is essential to prevent the progression of muscle weakness in mdx mice.

Lipid peroxidation and human sperm motility: protective role of vitamin E

Asthenospermia is the main factor of male infertility among patients consulting the Asir Infertility Center in Abha, Saudi Arabia. Lipid peroxidation occurring in both the seminal plasma and spermatozoa was estimated by malondialdehyde (MDA) concentration. Spermatozoal MDA concentration was higher in men with decreased sperm motility. The MDA concentration in the seminal plasma exhibited no relationship with sperm concentration, sperm motility, the number of immotile spermatozoa, or even the absence of spermatozoa. The MDA concentration in sperm pellet suspensions of asthenospermic and oligoasthenospermic patients was almost twice that of the normospermic males. The MDA concentration in the sperm pellet suspension from normospermic or oligospermic patients was about 10% that in the seminal plasma. However, the MDA concentration in the sperm pellet suspension of asthenospermic or oligoasthenospermic patients was about 15% that in the seminal plasma. Treatment of asthenospermic patients with oral Vitamin E significantly decreased the MDA concentration in spermatozoa and improved sperm motility. Eleven out of the 52 treated patients (21%) impregnated their spouses; nine of the spouses successfully ended with normal term deliveries, whereas the other two aborted in the first trimester. No pregnancies were reported in the spouses of the placebo-treated patients.

Vitamin E and vitamin C supplement use and risk of all-cause and coronary heart disease mortality in older persons: the Established Populations for Epidemiologic Studies of the Elderly

We examined vitamin E and vitamin C supplement use in relation to mortality risk and whether vitamin C enhanced the effects of vitamin E in 11,178 persons aged 67-105 y who participated in the Established Populations for Epidemiologic Studies of the Elderly in 1984-1993. Participants were asked to report all nonprescription drugs currently used, including vitamin supplements. Persons were defined as users of these supplements if they reported individual vitamin E and/or vitamin C use, not part of a multivitamin. During the follow-up period there were 3490 deaths. Use of vitamin E reduced the risk of all-cause mortality [relative risk (RR) = 0.66; 95% CI: 0.53, 0.83] and risk of coronary disease mortality (RR = 0.53; 95% CI: 0.34, 0.84). Use of vitamin E at two points in time was also associated with reduced risk of total mortality compared with that in persons who did not use any vitamin supplements. Effects were strongest for coronary heart disease mortality (RR = 0.37; 95% CI: 0.15, 0.90). The RR for cancer mortality was 0.41 (95% CI: 0.15, 1.08). Simultaneous use of vitamins E and C was associated with a lower risk of total mortality (RR = 0.58; 95% CI: 0.42, 0.79) and coronary mortality (RR = 0.47; 95% CI: 0.25, 0.87). Adjustment for alcohol use, smoking history, aspirin use, and medical conditions did not substantially alter these findings. These findings are consistent with those for younger persons and suggest protective effects of vitamin E supplements in the elderly.

Role of oxidative stress in transition of hypertrophy to heart failure

OBJECTIVES

In an attempt to define the role of increased oxidative stress in the transition from compensatory hypertrophy to heart failure, this study examined the effects of long-term vitamin E therapy on the occurrence of heart failure subsequent to chronic pressure overload in guinea pigs.

BACKGROUND

Hyperfunctional heart hypertrophy has been shown to be accompanied by an increase in the endogenous antioxidant reserve, whereas congestive heart failure is accompanied by a decrease in this reserve. The effects of vitamin E, a naturally occurring antioxidant, on the development of heart failure from a hypertrophic stage were examined.

METHODS

The ascending aorta in guinea pigs was coarcted. For vitamin treatment, slow-release pellets were implanted at the time of the operation. The animals were assessed at 10 and 20 weeks for hemodynamic function, myocardial structure, antioxidant agents and oxidative stress.

RESULTS

Banding of the ascending aorta in guinea pigs resulted in hyperfunctional hypertrophy at 10 weeks, which was followed by congestive heart failure at 20 weeks. Hypertrophied hearts showed decreased oxidative stress, as evidenced by a higher oxidation-reduction (redox) state and less lipid peroxidation, whereas the failure stage was characterized by increased oxidative stress. Supplementation of animals with timed-release vitamin E tablets resulted in an increased myocardial content of the vitamin, and the banded animals did not develop any signs of heart failure at 20 weeks. Hemodynamic function at 20 weeks in these vitamin E-treated animals was also better maintained. The myocardial reduced glutathione/oxidized glutathione ratio of vitamin E-treated animals at 20 weeks was higher and lipid peroxidation was less compared with the untreated animals. Ultrastructural abnormalities were significantly less in the vitamin E-treated hearts compared with the untreated failing hearts at 20 weeks.

CONCLUSIONS

An improved myocardial redox state with vitamin E therapy, coupled with the modulation of the development of heart failure, may indicate a pathophysiologic role for increased oxidative stress in the pathogenesis of heart failure. This study suggests the potential therapeutic value of long-term antioxidant treatment in modulating or preventing the pathogenesis of heart failure.

Vitamin C prevents oxidative damage

Ascorbate-deficiency leads to extensive oxidative damage of proteins and protein loss in the guinea pig tissue microsomes as evidenced by sodium dodecyl sulfate polyacrylamide gel electrophoresis, accumulation of carbonyl, bityrosine as well as by tryptophan loss. Oxidative damage is reversed by ascorbate therapy. Oxidative damage in ascorbate deficiency also leads to lipid peroxidation in guinea pig tissue microsomes as evidenced by accumulation of conjugated dienes, malondialdehyde and fluorescent pigment. Lipid peroxides, disappear after ascorbate therapy but not by vitamin E. The observations substantiate the previous in vitro findings that ascorbate specifically prevents oxidative degradation of microsomal membranes. The results indicate that vitamin C may exert a powerful protection against degenerative diseases associated with oxidative damage and play a critical role in wellness and health maintenance.

Intake of vitamins A, C, and E and postmenopausal breast cancer. The Iowa Women's Health Study

The association between dietary antioxidant vitamin intake and the risk of breast cancer was examined in a prospective study of 34,387 postmenopausal women in Iowa. Intakes of vitamins A, C, and E and of retinol and carotenoids were assessed in 1986 by mailed semiquantitative food frequency questionnaire. Through December 31, 1992, 879 incident breast cancer cases occurred in this cohort. There was little suggestion that breast cancer risk was associated with differences in intake of these vitamins. For example, from the lowest to highest total vitamin A intake categorized by quintiles, the age-adjusted relative risks of breast cancer were 1.0, 0.95, 1.17, 1.20, and 0.90 (p trend = 0.92). Similarly unremarkable relative risk patterns were seen for the intakes of vitamins C and E and of retinol and carotenoids. These findings were not altered after adjustment for breast cancer risk factors or in analyses confined to women who reported no supplemental vitamin intake. Exclusion of cases that occurred in the first 2 years of follow-up, under the assumption that women may have increased intake of these vitamins in response to preclinical symptoms of breast cancer, did not suggest an inverse association of these vitamins with the risk of breast cancer. Women who reported consuming at least 500 mg/day of supplemental vitamin C had a relative risk of breast cancer of 0.79 compared with women who did not take supplemental vitamin C, and women who reported consuming more than 10,000 IU/day of vitamin A had a corresponding relative risk of 0.73. However, these relative risks were not statistically significant. These results provide little evidence that intake of these vitamins is associated with breast cancer risk.

Vitamin E deficiency in variant angina

BACKGROUND

Oxidative modification of LDL has been suggested to increase coronary vasoreactivity to agonists. A deficiency of vitamin E, a major antioxidant, may be related to the occurrence of coronary artery spasm.

METHODS AND RESULTS

Vitamin E levels were determined with the use of high-performance liquid chromatography in normolipidemic subjects, including 29 patients with active variant angina (group 1), 13 patients with inactive stage of variant angina without anginal attacks during the past 6 months (group 2), 32 patients with a significant (>75%) organic coronary stenosis and stable effort angina (group 3), and 30 patients without coronary artery disease (group 4). Total lipid levels in blood were calculated as total cholesterol plus triglyceride levels. The plasma alpha-tocopherol levels as well as alpha-tocopherol/lipids were significantly lower in group 1 than in groups 2 through 4. Also, the plasma gamma-tocopherol levels were significantly lower in group 1 than in groups 2 through 4. The vitamin E levels were not significantly different between group 1 patients with and those without a significant organic stenosis. In group 1, both alpha- and gamma-tocopherol levels were significantly elevated after a > or = 6-month angina-free period. The alpha-tocopherol levels in the LDL fraction were significantly lower in group 1 than in group 4. Plasma alpha-tocopherol levels were significantly correlated with those in the LDL fractions. In 6 patients of group 1 still having anginal attacks while receiving calcium channel blockers, the addition of vitamin E acetate (300 mg/d) significantly elevated plasma alpha-tocopherol levels and inhibited the occurrence of angina.

CONCLUSIONS

Plasma vitamin E levels were significantly lower in patients with active variant angina than in subjects without coronary spasm, suggesting an association between vitamin E deficiency and coronary artery spasm.

Supplementation with carotenoids corrects increased lipid peroxidation in children with cystic fibrosis

Evidence of lipid peroxidation previously documented in cystic fibrosis (CF) implies an imbalance between free radical generation and antioxidant defense mechanisms. The aim of the present study was to examine the relation between plasma concentrations of malondialdehyde, a marker of lipid peroxidation, and the exogenous antioxidant line of defense. Malondialdehyde concentrations (90.2 +/- 4.7 nmol/L) in 25 children with CF aged 9.6 +/- 0.8 y were higher (P < 0.001) than concentrations (69.1 +/- 2.6 nmol/L) in 17 children used as control subjects and were not correlated with any marker of disease severity. In contrast with their all-rac-alpha-tocopherol status, which was normal as a result of routine supplementation with a 200-mg dose of all-rac-alpha-tocopheryl acetate/d, beta-carotene was very low. A 2-mo open trial in which 12 children with CF aged 11.5 +/- 0.8 y were given 4.42 mg (8.23 mumol) beta-carotene three times per day led to normalization of the malondialdehyde concentration in all but 1 patient, in conjunction with an increase of plasma beta-carotene from 0.08 +/- 0.03 to 3.99 +/- 0.92 mumol/L. Their plasma concentrations were inversely correlated (r = -0.54, P = 0.006) [corrected] with malondialdehyde when the values measured pre- and posttreatment were pooled. We conclude that beta-carotene deficiency contributes to lipid peroxidation in CF and that supplementation may eventually prove to be a useful adjunct for the management of the disease.

Effectiveness of antioxidants (vitamin C and E) with and without sunscreens as topical photoprotectants

Considerable interest has been recently generated concerning the use of natural compounds, anti-oxidants in particular, in photoprotection. Two of the best known anti-oxidants are vitamins C and E, both of which have been shown to be somewhat effective in different models of photodamage. Very little has been reported, however, on the effectiveness of a combination of the two (known to be biologically the more relevant situation); nor have there been detailed studies on the ability of these antioxidants to augment commercial sunscreen protection against UV damage. We report that (in swine skin) vitamin C is capable of additive protection against acute UVB damage (sunburn cell formation) when combined with a UVB sunscreen. A combination of both vitamins E and C provided very good protection from a UVB insult, the bulk of the protection attributable to vitamin E. However, vitamin C is significantly better than vitamin E at protecting against a UVA-mediated phototoxic insult in this animal model, while the combination is only slightly more effective than vitamin C alone. When vitamin C or a combination of vitamin C and E is formulated with a commercial UVA sunscreen (oxybenzone), an apparently greater than additive protection is noted against the phototoxic damage. These results confirm the utility of anti-oxidants as photoprotectants but suggest the importance of combining the compounds with known sunscreens to maximize photoprotection.

[An antioxidant in pediatrics]

The authors review the state of the art regarding vitamin E in relation to its use during childhood. The report comments on a number of aspects which are still not entirely clear and stresses the prophylactic and therapeutic importance of antioxidants, even in pediatrics, and the severe damage that may result from free radicals even during this period of life.

Influence of verapamil on the efficacy of vitamin E in preventing the ischemia-reperfusion-induced biochemical dearrangement in cerebral cortex of rat

The possibility that verapamil (CAS 52-53-9) may intensify the efficacy of vitamin E in preventing the ischemia-reperfusion-caused biochemical dearrangement in rat cerebral cortex was investigated. A daily injection of vitamin E at i.m. dose of 175 mg/kg b.wt. for 7 days prior to subjecting the rats to 1 h bilateral occlusion of the common carotid arteries followed by reperfusion for another 1 h, moderately diminished the ischemia-reperfusion-induced increase in the activity of lactate dehydrogenase and in formation of conjugated dienes as well as in the conversion of xanthine dehydrogenase-->xanthine oxidase in cerebral cortex of rats. However, concomitant injection of verapamil at i.m. dose of 0.68 mg/kg b.wt. 15 min prior to ischemia-reperfusion together with vitamin E pretreatment afforded an elegant combined therapy that effectively abolished the dearrangement caused by ischemia-reperfusion in the above parameters. These results indicated that the protective efficacy of vitamin E against ischemia/reperfusion-induced biochemical dearrangement in cerebral cortex was intensified by concomitant use of verapamil.

Perchloroethylene-induced alterations in glucose metabolism and their prevention by 2-deoxy-D-glucose and vitamin E in mice

The effect of 2-deoxy-D-glucose (2DG) and vitamin E on the alterations in glucose metabolism induced by perchloroethylene (PER) was studied in mice. Oral administration of PER (3 g kg-1 body wt. day-1) in sesame oil for 15 days caused a significant increase in liver weight, degeneration/necrosis of hepatocytes and increase in kidney weight, glomerular nephrosis and degeneration. These changes occurred concurrently with a significant decrease in blood glucose level, elevated activities of hexokinase, aldolase and phosphoglucoisomerase and decreased activity of gluconeogenic enzymes (glucose-6-phosphatase and fructose-1,6-diphosphatase), indicating the sensitivity of liver and kidney as target tissues in PER toxicity. Evidence is presented that both 2DG (500 mg kg-1 body wt. day-1 i.p.) and vitamin E (400 mg kg-1 body wt. day-1 by oral gavage) during concomitant administration prevented most of the above PER-induced biochemical and pathological alterations. These results suggest that early metabolic and pathological perturbations following exposure of PER in mice can provide the basis for its documented potential for chronic effects like cytotoxicity and may be involved in modulation of carcinogenicity.

Vitamin E: hype or hope

Unlike other vitamins, Vitamin E probably has received less attention in the past because humans are not likely to suffer from deficiency disorders. This fat soluble vitamin is available in many foods, is easily stored, and is readily reused by the body. The original research carried out in the 1920s found that a Vitamin E deficiency in rats produced problems in their reproductive capacity. The name given to the substance at that time, "tocopherol," reflects this action as it is taken from the Greek word, "tocos," meaning "to give birth."

Impairment of endothelium dependent relaxation in the diabetic rat heart: mechanisms and implications

An increased oxidative stress has been suggested to contribute to disturbances in the regulation of coronary flow and the increased cardiac risk in diabetes. Using the isolated perfused heart of streptozotocin-diabetic rats we could recently show [21] that the basal and the maximal coronary flow (tested by infusion of sodium nitroprusside) are not altered in diabetes, but that the 5-HT stimulated endothelial dependent increase in coronary flow becomes progressively impaired. This defect of the endothelium dependent vasodilatation was prevented by perfusion of the hearts with superoxide dismutase and pre-treatment of the diabetic rats with tocopherol-acetate. Perfusion of the hearts with indomethacin to inhibit the synthesis of vasoconstricting prostaglandin endoperoxides did not improve the disturbed 5-HT induced, endothelium dependent increase in coronary flow. Furthermore, acute variations of the glucose concentration in the perfusion medium did not affect the coronary flow significantly. In myocardium, the constitutive endothelial NO synthetase was nearly exclusively expressed with the highest activity in endothelium, as determined from experiments using isolated cardiac endothelial cells. The activity of NO synthetase determined by conversion of arginine to citrulline was significantly increased in diabetes. In line with this observation, the concentration of arginine in plasma was reduced, but that of citrulline elevated. Additionally, the renal elimination of nitrite was enhanced in diabetes. These data suggest that the impaired endothelium dependent relaxation observed in the diabetic myocardium is presumably not caused by a diminished synthesis and release of NO, but by an accelerated inactivation of NO by superoxide anions. We suggest that the increased NO generation reflects a compensatory mechanism to balance the enhanced inactivation of NO.