Medical uses of vitamin E

Neurovascular coupling impairment as a mechanism for cognitive deficits in COVID-19

Components that comprise our brain parenchymal and cerebrovascular structures provide a homeostatic environment for proper neuronal function to ensure normal cognition. Cerebral insults (e.g. ischaemia, microbleeds and infection) alter cellular structures and physiologic processes within the neurovascular unit and contribute to cognitive dysfunction. COVID-19 has posed significant complications during acute and convalescent stages in multiple organ systems, including the brain. Cognitive impairment is a prevalent complication in COVID-19 patients, irrespective of severity of acute SARS-CoV-2 infection. Moreover, overwhelming evidence from in vitro, preclinical and clinical studies has reported SARS-CoV-2-induced pathologies in components of the neurovascular unit that are associated with cognitive impairment. Neurovascular unit disruption alters the neurovascular coupling response, a critical mechanism that regulates cerebromicrovascular blood flow to meet the energetic demands of locally active neurons. Normal cognitive processing is achieved through the neurovascular coupling response and involves the coordinated action of brain parenchymal cells (i.e. neurons and glia) and cerebrovascular cell types (i.e. endothelia, smooth muscle cells and pericytes). However, current work on COVID-19-induced cognitive impairment has yet to investigate disruption of neurovascular coupling as a causal factor. Hence, in this review, we aim to describe SARS-CoV-2's effects on the neurovascular unit and how they can impact neurovascular coupling and contribute to cognitive decline in acute and convalescent stages of the disease. Additionally, we explore potential therapeutic interventions to mitigate COVID-19-induced cognitive impairment. Given the great impact of cognitive impairment associated with COVID-19 on both individuals and public health, the necessity for a coordinated effort from fundamental scientific research to clinical application becomes imperative. This integrated endeavour is crucial for mitigating the cognitive deficits induced by COVID-19 and its subsequent burden in this especially vulnerable population.

Vitamin E Supplement Protects Against Gestational Diabetes Mellitus in Mice Through nuclear factor-erythroid factor 2-related factor 2/heme oxygenase-1 Signaling Pathway

Background

Gestational diabetes mellitus (GDM) is the most common pregnant disorder worldwide. In this study, we aimed to explore whether vitamin E (VE) treatment alone could protect against GDM in a mouse model.

Methods

6-week-old C57BL/6J female mice were fed on high-fat diet for two weeks and continued with high-fat diet after pregnancy to induce GDM. The pregnant mice were orally administrated with 2.5, 25 or 250 mg/kg VE twice per day during pregnancy together with high-fat diet. Oral glucose tolerance test, insulin amounts, oxidative stress and inflammation were then measured.

Results

Only 250 mg/kg VE could improve glucose tolerance and insulin level in pregnant mice. VE (250 mg/kg) effectively inhibited GDM-induced hyperlipidemia, and secretion of inflammatory cytokines such as tumor necrosis factor-α and interleukin-6. VE also significantly ameliorated maternal oxidative stress at the late stage of pregnancy, and also improved reproductive outcomes, including increasing the litter size and birth weight in GDM mice. Moreover, VE also activated GDM-reduced nuclear factor-erythroid factor 2-related factor 2 (Nrf2) / heme oxygenase-1 signaling pathway in the maternal liver tissues of GDM mice.

Conclusion

Our data clearly demonstrated that 250 mg/kg VE twice a day during pregnancy could significantly ameliorate the symptoms of GDM by alleviating oxidative stress, inflammation, hyperglycemia, and hyperlipidemia through Nrf2/HO-1 signaling pathway in GDM mice. Thus, additional VE supplement might be beneficial to GDM.

Molecular mechanisms and therapeutic effects of different vitamins and minerals in COVID-19 patients

COVID-19 is a rapidly spreading disease, which has caught the world by surprise. Millions of people suffer from illness, and the mortality rates are dramatically high. Currently, there is no specific and immediate treatment for this disease. Remedies are limited to supportive regiments and few antiviral and anti-inflammatory drugs. The lack of a definite cure for COVID-19 is the reason behind its high mortality and global prevalence. COVID-19 can lead to a critical illness with severe respiratory distress and cytokine release. Increased oxidative stress and excessive production of inflammatory cytokines are vital components of severe COVID-19. Micronutrients, metalloids, and vitamins such as iron, manganese, selenium, Zinc, Copper, vitamin A, B family, and C are among the essential and trace elements that play a pivotal role in human nutrition and health. They participate in metabolic processes that lead to energy production. In addition, they support immune functions and act as antioxidants. Therefore, maintaining an optimal level of micronutrients intake, particularly those with antioxidant activities, is essential to fight against oxidative stress, modulate inflammation, and boost the immune system. Therefore, these factors could play a crucial role in COVID-19 prevention and treatment. In this review, we aimed to summarize antiviral properties of different vitamins and minerals. Moreover, we will investigate the correlation between them and their effects in COVID-19 patients.

Pretreatment Dietary Patterns, Serum Carotenoids and Tocopherols Influence Tumor Immune Response in Head and Neck Squamous Cell Carcinoma

BACKGROUND

Tumor infiltrating lymphocytes (TILs) aid in informing treatment for head and neck squamous cell carcinoma (HNSCC). Nevertheless, little is known about the role of diet on TILs.

METHODS

Immunohistologic expression of CD4, CD8, CD68, CD103, CD104 and FOXP3 were assessed in tissue microarrays from 233 previously untreated HNSCC patients. Associations between these markers and pretreatment dietary patterns were evaluated using linear regression. Associations between baseline serum carotenoids, tocopherols and TILs were assessed using logistic regression. Cox models evaluated the association between diet and TILs on overall and recurrence-free survival.

RESULTS

Consumption of a Western dietary pattern was associated with lower CD8+ and FOXP3+ infiltrates (p-value:0.03 and 0.02, respectively). Multivariable logistic regression models demonstrated significantly higher CD8+ (OR:2.21;p-value:0.001) and FOXP3+ (OR:4.26;p-value:<0.0001) among patients with high gamma tocopherol. Conversely, high levels of xanthophylls (OR:0.12;p-value:<0.0001), lycopene (OR:0.36;p-value:0.0001) and total carotenoids(OR:0.31;p-value: <0.0001) were associated with significantly lower CD68+. Among those with high CD4+ (HR:1.77;p-value:0.03), CD68+ (HR:2.42;p-value:0.004), CD103+ (HR:3.64;p-value:0.03) and FOXP3+ (HR:3.09;p-value:0.05), having a high Western dietary pattern increased the risk of overall mortality when compared to a low Western dietary pattern.

CONCLUSION

Dietary patterns and serum carotenoids may play an important role in modifying TILs, and ultimately, outcome after diagnosis with HNSCC.

Could Vitamins Help in the Fight Against COVID-19?

There are limited proven therapeutic options for the prevention and treatment of COVID-19. The role of vitamin and mineral supplementation or "immunonutrition" has previously been explored in a number of clinical trials in intensive care settings, and there are several hypotheses to support their routine use. The aim of this narrative review was to investigate whether vitamin supplementation is beneficial in COVID-19. A systematic search strategy with a narrative literature summary was designed, using the Medline, EMBASE, Cochrane Trials Register, WHO International Clinical Trial Registry, and Nexis media databases. The immune-mediating, antioxidant and antimicrobial roles of vitamins A to E were explored and their potential role in the fight against COVID-19 was evaluated. The major topics extracted for narrative synthesis were physiological and immunological roles of each vitamin, their role in respiratory infections, acute respiratory distress syndrome (ARDS), and COVID-19. Vitamins A to E highlighted potentially beneficial roles in the fight against COVID-19 via antioxidant effects, immunomodulation, enhancing natural barriers, and local paracrine signaling. Level 1 and 2 evidence supports the use of thiamine, vitamin C, and vitamin D in COVID-like respiratory diseases, ARDS, and sepsis. Although there are currently no published clinical trials due to the novelty of SARS-CoV-2 infection, there is pathophysiologic rationale for exploring the use of vitamins in this global pandemic, supported by early anecdotal reports from international groups. The final outcomes of ongoing trials of vitamin supplementation are awaited with interest.

Treatment of tardive dyskinesias with vitamin E*

The hypothesis that tardive dyskinesias observed after long-term administration of neuroleptics are due to the formation of free radicals following this medication has prompted studies on the use of vitamin E (α-tocopherol), an antioxidant to treat patients suffering from such side-effects. The present study aimed at reproducing earlier encouraging results in treating 23 patients with vitamin E, using a double-blind crossover design. Inclusion criteria were: duration of tardive dyskinesia for at least 3 months, appearance of the symptoms during neuroleptic treatment or after stopping this kind of medication. The 10 subjects in the first group (Gl) were treated for 14 days with 1 200 mg vitamin E per day and then for 14 days with placebo. For the second group (G2) with 9 subjects, the treatment periods were inversed. The 2 dropouts in each group were not due to experimental problems: there was no complication due to vitamin E intake, or only negligible side-effects. Side-effects were rated on the AIM scale on days 0, 14 and 28. The results of the present study do not confirm earlier reports: there was no significant difference in the therapeutic effect between placebo and vitamin E in any of the groups. However, the fact of taking these symptoms into account in the physician-patient relationship has contributed significantly to a decrease of tardive dyskinesia in both groups, from the beginning until the end of the investigation period, during which both neuroleptic and tranquilizing treatments were kept constant. Further studies should include longer treatment periods with vitamin E or even test the preventive effect of vitamin E in the production of tardive dyskinesia by neuroleptics.

Vitamin E and Discoid Lupus Erythematosus

We treated seven patients with discoid lupus erythematosus (DLE) with Vitamin E in an oral dose of 400 mg three times per day for 12 weeks. All other systemic and topical treatments were discontinued 1 month before initiation of the trial. The drug was then stopped and follow-up continued for at least another 4 weeks. No patient showed clearing of lesions. The trial was conducted during summer, when DLE is likely to be most active. There was no deterioration in any patient. No side effects were noted.

Anti-depressant and anxiolytic potential of Acacia hydaspica R. Parker aerial parts extract: Modulation of brain antioxidant enzyme status

BACKGROUND

Oxidative stress may link to psychiatric disorders, and is being regarded as a plausible mechanism that can affect the regulation of these illnesses. The present study was undertaken to investigate the antidepressant and anxiolytic potential of A. hydaspica R. parkers. Brain oxidative stress enzyme levels were analyzed to correlate depression and stress with brain antioxidant status.

METHODS

Antidepressant and anxiolytic effect of methanol extract of A. hydaspica and its derived soluble fractions [n-hexane (AHH), ethyl-acetate (AHE), chloroform (AHC), n-butanol (AHB) and remaining aqueous fraction (AHA)] was investigated by using three behavioral models; the Forced swimming test, Tail suspension test and Elevated plus-maze test (EPM). Chronic unpredictable mild stress (CMS) was employed to induce stress in rats. AHM and AHE (200 mg/kg, p.o), fluoxetine (5 mg/kg, i.p) and diazepam (DZM) (1 mg/kg, p.o) were administered during the 7 day stress exposure period, and rats were assessed for antidepressant and anxiolytic behavioral despair paradigms. Antioxidant enzymes and oxidative stress markers were measured in brain tissue of depressed rats. Phytochemical analysis was done by GCMS experimentation.

RESULTS

AHM and AHE (acute dose) significantly (p < 0.0001) reduced the immobility time and ameliorated climbing behavior as compared to the control in FST and TST, and similar to fluoxetine. AHM and AHE showed significant (p < 0.0001) anxiolytic potential in EPM, and comparable to DZM (1 mg/kg b.w., i.p). Significant decrease in antioxidant enzyme levels and increase in MDA, H2O2 and NO level were observed in stressed rats. AHM and AHE (for 7 days/CMS) significantly improved behavior in FST, TST and EPMT. Treatment also improved antioxidant enzyme level and controlled the oxidative stress markers in brain tissues. GCMS analysis indicated the presence of 10 different chemical constituents in A. hydaspica.

CONCLUSION

The present study revealed that A. hydaspica exerts an antidepressant and anxiolytic effect by improving brain antioxidant status. The observed activities might be due to the presence of diverse phytochemicals.

Vitamin E Nicotinate

Vitamin E refers to a family of compounds that function as lipid-soluble antioxidants capable of preventing lipid peroxidation. Naturally occurring forms of vitamin E include tocopherols and tocotrienols. Vitamin E in dietary supplements and fortified foods is often an esterified form of α-tocopherol, the most common esters being acetate and succinate. The vitamin E esters are hydrolyzed and converted into free α-tocopherol prior to absorption in the intestinal tract. Because its functions are relevant to many chronic diseases, vitamin E has been extensively studied in respect to a variety of diseases as well as cosmetic applications. The forms of vitamin E most studied are natural α-tocopherol and the esters α-tocopheryl acetate and α-tocopheryl succinate. A small number of studies include or focus on another ester form, α-tocopheryl nicotinate, an ester of vitamin E and niacin. Some of these studies raise the possibility of differences in metabolism and in efficacy between vitamin E nicotinate and other forms of vitamin E. Recently, through metabolomics studies, we identified that α-tocopheryl nicotinate occurs endogenously in the heart and that its level is dramatically decreased in heart failure, indicating the possible biological importance of this vitamin E ester. Since knowledge about vitamin E nicotinate is not readily available in the literature, the purpose of this review is to summarize and evaluate published reports, specifically with respect to α-tocopheryl nicotinate with an emphasis on the differences from natural α-tocopherol or α-tocopheryl acetate.

Reducing Cancer Risk with Vitamins C, E, and Selenium

Current research has provided evidence that nearly 90 percent of all cancers may be related to diet, environment, and lifestyle. Of this number, 30 to 40 percent of cancers in men and up to 60 percent of cancers in women may be related to diet and nutrition. The two-stage process in the formation of many cancers, defined as initiation and promotion, is influenced by many dietary components. Vitamins C, E, and the mineral selenium are nutrients that function as antioxidants, reducing potential cancer-causing chemicals in the body. These natural anticarcinogens are thought to alter the cancer process and are currently under study for their cancer prevention properties. The functions, Recommended Dietary Allowances, food sources, research evidence for cancer prevention, and recommendations for supplementation are presented for these three nutrients. Research suggests that the proper and prudent use of nutrients, along with a healthy diet and lifestyle, may offer protection against this devastating disease.

Nutritional status and its response to treatment of children, with and without HIV infection, hospitalized for the management of tuberculosis

BACKGROUND

The association of childhood tuberculosis (TB) and malnutrition is known, but treatment response, the influence of the acute-phase response (APR) and concomitant HIV infection are not well documented.

AIM

To evaluate the nutritional response and APR in HIV-infected and uninfected children hospitalised for the treatment of TB and receiving standard anti-tuberculosis chemotherapy.

METHODS

During a study of the pharmacokinetics of standard anti-tuberculosis agents, anthropometric parameters were measured and blood concentrations of nutrients and C-reactive protein (CRP) determined at 1 and 4 months after initiation of chemotherapy.

RESULTS

24 HIV-infected and 34 HIV-uninfected children were studied. On enrollment, 31.6% of HIV-infected and 2.9% of HIV-uninfected children were underweight, and 31.6% and 14.7%, respectively, were stunted. Mean values of weight, height/length, head circumference and mid-upper-arm circumference on enrollment and at 4-month assessment in HIV-infected and uninfected children did not differ. Mean triceps skinfold (TSF) (8.17 and 9.73 cm) and subscapular skinfold (SSF) thicknesses (5.75 and 7.5 cm) on enrollment differed significantly (P = 0.03 and P = 0.003); by 4 months, TSF had declined to 5.97 cm (P<0.001) and 8.87 cm (P = 0.05), respectively, and SSF to 5.57 cm (P = 0.79) and 6.73 cm (P = 0.04); the arm muscle area (AMA) was low in a majority of children on enrollment and remained so at the second assessment. CRP was raised in 66.6% and 53.3% of HIV-infected and -uninfected children on enrollment, but at 4-month assessment was raised in 63.2% and 15.2%, respectively. Other micronutrient and haematological findings probably reflect an APR, but no children had sub-normal zinc or magnesium values; most selenium and vitamin C and E values were normal. An elevated platelet count (> 420 × 10(9)/L) was significantly more common in HIV-uninfected children, and was still raised in 39% at 4 months.

CONCLUSION

A majority of HIV-infected and uninfected children had an APR but it had resolved by 4 months in most HIV-uninfected children. In both groups, low and declining skinfolds and a persistently low AMA indicate a persistent disturbance of fat and protein metabolism, despite successful chemotherapy.

Asymmetric dimethylarginine (ADMA) determines the improvement of hepatic endothelial dysfunction by vitamin E in cirrhotic rats

BACKGROUND

Hepatic endothelial dysfunction (HED), which is caused by decreased hepatic nitric oxide (NO) bioavailability and increased lipid peroxidation, contributes to portal hypertension, which is a characteristic of cirrhosis. Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase (NOS), is involved in cirrhosis-related HED and portal hypertension.

AIMS

We evaluated the effect of vitamin E treatment on the lipid peroxidation, HED and portal hypertension in cirrhotic rats.

METHODS

The common bile duct ligation (BDL)-induced cirrhotic rats were treated orally either with vehicle or with vitamin E for 1 month immediately after BDL. Systemic and portal haemodynamics, the magnitude of the increase in portal pressure induced by volume expansion, HED, oxidative stress, levels of ADMA, various proteins and mRNAs were then measured.

RESULTS

In the vitamin E-treated BDL rats, a decrease in portal pressure was associated with an attenuation of the increased portal pressure induced by volume expansion. In isolated and perfused BDL rat livers, the vitamin E treatment significantly inhibited the (paradoxical) vasoconstriction response to methoxamine and acetylcholine (HED), and this was abolished by the presence of NOS. Vitamin E decreased ADMA synthesizing enzyme PRMT1 expression and the level of thiobarbituric acid-reactive substances (TBARS) in the liver, while increasing the levels of hepatic ADMA metabolizing enzyme DDAH2, eNOS, phosphor-eNOS, ADMA level and superoxide dismutase activity.

CONCLUSIONS

The administration of vitamin E suppressed hepatic ADMA and oxidative stress in the cirrhotic liver circulation, and therefore increases NO bioavailability, which improved HED and portal hypertension.

Dose-response relationship for α-tocopherol prevention of ultraviolet radiation induced cataract in rat

The purpose of this study is to establish the dose response relationship for α-tocopherol protection of ultraviolet radiation (UVR) induced cataract in the rat. Four groups of 20 six-week-old albino Sprague Dawley rats received 5, 25, 50, and 100 IU/day α-tocopherol, whilst another group of 20 rats without any α-tocopherol feeding was the control group. After 4 weeks of feeding, each rat was unilaterally exposed to 8 kJ/m(2) UVR-300 nm for 15 min. At 1 week after exposure, the rats were sacrificed and lens light scattering was measured quantitatively. Lens total reduced (GSH) and oxidized (GSSG) glutathione; glutathione reductase (GR) and peroxidase (GPx) were determined spectrophotometrically. The UVR-exposed lenses in the α-tocopherol fed groups developed superficial cataract, whereas lenses in the control group developed cortical and equatorial opacities. Light scattering in lenses from the α-tocopherol-supplemented rats was lower than in lenses from the control group. The difference of light scattering between the exposed and contralateral non-exposed lens decreased with increasing doses of α-tocopherol to an asymptote level. UVR-exposure caused a significant depletion of lens GSH in rats without or at low α-tocopherol supplementation. The depletion of GSH became less with higher α-tocopherol supplementation. There was no detectable difference in lens GSSG, GR or GPx at any level of α-tocopherol supplementation. Orally administered α-tocopherol dose dependently protects against UVR-induced cataract. The protection is associated with an α-tocopherol dose-dependent GSH depletion secondary to UVR exposure. UVR-induced light scattering only occurs if the GSH depletion exceeds a threshold.

Vitamin E in human health and disease

Vitamin E in nature is comprised of a family of tocopherols and tocotrienols. The most studied of these is alpha-tocopherol (alpha-TOH), because this form is retained within the body, and vitamin E deficiency is corrected with this supplement. alpha-TOH is a lipid-soluble antioxidant required for the preservation of cell membranes, and it potentially acts as a defense against oxidative stress. Many studies have investigated the metabolism, transport, and efficacy alpha-TOH in the prevention of sequelae associated with cardiovascular disease (CVD). Supplementation with vitamin E is considered to provide health benefits against CVD through its antioxidant activity, the prevention of lipoprotein oxidation, and the inhibition of platelet aggregation. However, the results from large prospective, randomized, placebo-controlled clinical trials with alpha-TOH have been largely negative. A recent meta-analysis suggests that alpha-TOH supplements may actually increase all-cause mortality; however, the mechanism for this increased risk is unknown. In vitro studies performed in human cell cultures and animal models suggest that vitamin E might increase the hepatic production of cytochrome P450s and MDR1. Induction of CYP3A4 or MDR1 by vitamin E could potentially lower the efficacy of any drug metabolized by CYP3A4 or MDR1. Other possibilities include an adverse effect of alpha-TOH on blood pressure in high-risk populations. Because of the wide popularity and use of vitamin E supplements, further research into potential adverse effects is clearly warranted.

Vitamin E and selenium supplementation and risk of prostate cancer in the Vitamins and lifestyle (VITAL) study cohort

OBJECTIVE

Vitamin E and selenium are promising nutrients for the prevention of prostate cancer, and both are currently being tested in a large randomized trial for prostate cancer. However, results are not expected for at least 6 years. We aimed to investigate the association of vitamin E and selenium supplementation with prostate cancer in the VITamins And Lifestyle (VITAL) study, a cohort study specifically designed to examine supplement use and future cancer risk.

METHODS

In a prospective design, 35,242 men recruited between 2000 and 2002 from western Washington State completed a questionnaire, including detailed questions about vitamin E and selenium supplement intake during the past 10 years from brand-specific multivitamins and single supplements. Using linkage to the western Washington SEER cancer registry, we documented 830 new cases of prostate cancer from baseline through December 2004.

RESULTS

A 10-year average intake of supplemental vitamin E was not associated with a reduced prostate cancer risk overall [hazard ratio (HR) 0.86, 95% confidence interval (CI) 0.65-1.1 for > or =400 IU/day vs. non-use, p for trend 0.36]; however, risk for advanced prostate cancer (regionally invasive or distant metastatic, n = 123) decreased significantly with greater intake of supplemental vitamin E (HR 0.43, 95% CI 0.19-1.0 for 10-year average intake > or =400 IU/day vs. non-use, p for trend 0.03). There was no association between selenium supplementation and prostate cancer risk (HR 0.90, 95% CI 0.62-1.3 for 10-year average intake >50 microg/day vs. non-use, p for trend 0.97).

CONCLUSIONS

In this prospective cohort, long-term supplemental intake of vitamin E and selenium were not associated with prostate cancer risk overall; however, risk of clinically relevant advanced disease was reduced with greater long-term vitamin E supplementation.

The interplay between uric acid and antioxidants in relation to physical function in older persons

OBJECTIVES

To investigate the relationship between circulating uric acid (UA) levels and plasma antioxidants and whether antioxidant levels modulate the association between UA and physical function.

DESIGN

Cross-sectional.

SETTING

Community-based.

PARTICIPANTS

Nine hundred sixty-six elderly persons participating in the baseline assessment of the Invecchiare in Chianti Study.

MEASUREMENTS

UA, carotenoid, tocopherol, and selenium concentrations were assayed. Physical function was measured using the Short Physical Performance Battery (SPPB) and difficulties in instrumental activities of daily living (IADLs). Potential confounders were assessed using standardized methods.

RESULTS

Total carotenoids (P=.008), in particular alpha-carotene (P=.02), lutein (P<.001), zeaxanthin (P<.001), lycopene (P=.07), cryptoxanthin (P=.29), and selenium (P=.04) were inversely associated with UA levels. Total tocopherols (P=.06) and alpha-tocopherol (P=.10) had a positive trend across UA levels. SPPB (P=.01) and IADL disability (P=.002) were nonlinearly distributed across the UA quintiles. Participants within the middle UA quintile (4.8-5.3 mg/dL) were less disabled in IADLs and had better SPPB scores than those in the extreme UA quintiles. There was a significant interaction between UA and selenium in the model predicting SPPB score (P=.02).

CONCLUSION

UA levels are inversely associated with circulating carotenoids and selenium. Participants with intermediate UA levels had a higher prevalence of good physical functions, higher SPPB scores, and lower IADL disability. This study suggests that older subjects with intermediate UA levels may have an optimum balance between proinflammatory and antioxidant compounds that may contribute to better physical performance.

“Over-The-Counter” Drug Toxicities in Companion Animals

A truly astonishing variety of "over-the-counter" drugs not taken under the auspices of a physician or veterinarian and not regulated by the Federal Drug Administration (FDA) are currently available to the American public. Many of these are widely advertised, readily available, remarkably inexpensive, and universally taken. Although most of the over-the-counter medications are fairly safe, the potential for toxic episodes exists due in large part simply on account of the amounts curious unsupervised animals may ingest. Another part of the problem is that since they are over the counter a large proportion of the public perceives them as totally harmless. In this article, we will investigate the most frequently seen non-prescription intoxications, their mechanism of action, clinical signs, diagnosis management, and prevention.

Advances in the use of tocols as drug delivery vehicles

There has been increasing interest in recent years in the drug delivery applications of tocols and their derivatives. Their biocompatibility and potential to deliver both poorly soluble and water-soluble drugs make tocols attractive as drug delivery vehicles. This review article will focus primarily on topical, oral, and parenteral drug administration using tocols, although other routes of delivery such as pulmonary and nasal will also be discussed. After an overview of the tocol structures, physicochemical properties with emphasis on their solvent properties, functions, and metabolism, specific case studies will be discussed where tocols have been successfully used in topical, oral, and parenteral drug formulations and marketed drug products. Case studies will be extended to those where tocol-based formulations were administered pulmonarily and nasally. As more clinical data and marketed drug products emerge, the utility and therapeutic value of tocols will certainly increase.

Protective role of Vitamin E pre-treatment on N-nitrosodiethylamine induced oxidative stress in rat liver

Nitrosamine compounds are known hepatic carcinogens. In the metabolism of nitrosamines, such as N-nitrosodiethylamine (NDEA), there is evidence of the formation of reactive oxygen species (ROS) resulting in oxidative stress, which may be one of the factors in the etiology of cancer. The formation of ROS may alter the antioxidant system, while the presence of Vitamin E may counteract NDEA induced oxidative stress. This study was planned to determine whether pre-treatment with Vitamin E (40 mg/kg body weight, i.p., twice a week for 4 weeks) to NDEA induced rats provides protection against oxidative stress in liver caused by the carcinogen. A single necrogenic dose of NDEA (200mg/kg body weight) was administered i.p. to the male albino rats with or without Vitamin E pre-treatment and the animals were sacrificed on Days 7, 14 or 21 after the administration of NDEA. The result showed enhanced levels of hepatic lipid peroxidation (LPO) and conjugated dienes of NDEA treated rats as the indices of oxidative stress, however, Vitamin E pre-treated rats administered NDEA showed decreased LPO and conjugated dienes (Day 21). Superoxide dismutase (SOD) activity in liver was not altered significantly in NDEA treated rats with or without Vitamin E pre-treatment. Catalase (CAT) activity was inhibited with NDEA treatment, however, Vitamin E pre-treatment showed recovery in hepatic CAT activity (Days 14 and 21). Total and Se-glutathione peroxidase (GSH-Px) activities and glutathione-S-transferase (GST) activity in liver increased in NDEA treated rats irrespective of Vitamin E pre-treatment. Glutathione reductase (GSH-R) activity as well as total glutathione (GSH) content in liver decreased in NDEA treated animals, both of which were recovered in Vitamin E pre-treated rats administered NDEA. Activities of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) were increased significantly following NDEA treatment to rats with or without Vitamin E pre-treatment. The activities of AST and ALT enzymes were significantly reduced on Days 14 and 21 and ALP activity was reduced on Day 21 in NDEA+Vitamin E treated animals when compared to NDEA treated alone. LDH enzyme activity was normalized on Day 14 in Vitamin E pre-treated animals administered NDEA. However, the AST, ALT and ALP enzyme activities remained high in all treatment groups as compared to control group. Normal control and Vitamin E treated alone rats revealed normal histology of liver. On the other hand, NDEA treated animals showed alterations in normal hepatic histoarchitecture, which comprised of necrosis and vacuolization of the cells. However, the rats treated with Vitamin E+NDEA showed that the liver cells were normal, with very little necrosis (Day 21). This study concludes that the pre-treatment with Vitamin E prior to the administration of NDEA, reduced the degree of oxidative stress, although this vitamin produced only slight changes in the hepatic injury, in a time-dependent manner.

Decreasing the oxidant stress from paraquat in isolated perfused rat lung using captopril and niacin

The abilities of captopril and niacin to protect against the lung toxicity of paraquat (PQ) were studied. The anti-oxidative action of captopril, an angiotensin-converting enzyme inhibitor, appears to be attributable to the sulphahydryl group (SH) in the compound, which gives captopril the ability to scavenge reactive oxygen species. Niacin replenishes the NAD and ATP depletion caused by reactive oxygen species. PQ causes lung damage in man and in several species of laboratory animals. The damage is initially manifested by hemorrhage and edema, and later by consolidation of the lung and fibrosis development. In this study, the lungs of male Wistar rats (250-300 g in weight) were perfused by Krebs-Ringer buffer alone (control), niacin (150 microM), captopril (10 microM) and PQ (600 microM) in perfusion fluid, and the biochemical changes that occurred in isolated rat lung were examined within 1 h and compared to PQ alone. The results show that captopril significantly decreases the lung weight/body weight ratio when used as a pretreatment and a post-treatment to captopril (p<0.0001). The results also show that captopril (10 microM) and niacin (150 microM) significantly decreases PQ-induced lung toxicity. Lactate dehydrogenase (LDH) activity significantly decreased in treatment groups as compared to the PQ group (p<0.0001). This study suggests that paraquat causes increased lipid peroxidation and LDH activity and decreased glutathione (GSH) and total protein in isolated perfused rat lung. These effects are reduced under these experimental conditions by captopril and niacin.

Vitamin E intake and risk of amyotrophic lateral sclerosis

Oxidative stress may contribute to the pathogenesis of amyotrophic lateral sclerosis (ALS). We therefore examined prospectively whether individuals who regularly use supplements of the antioxidant vitamins E and C have a lower risk of ALS than nonusers. The study population comprised 957,740 individuals 30 years of age or older participating in the American Cancer Society's Cancer Prevention Study II. Information on vitamin use was collected at time of recruitment in 1982; participants then were followed up for ALS deaths from 1989 through 1998 via linkage with the National Death Index. During the follow-up, we documented 525 deaths from ALS. Regular use of vitamin E supplements was associated with a lower risk of dying of ALS. The age- and smoking-adjusted relative risk was 0.99 (95% confidence interval [CI], 0.69-1.41) among occasional users, 0.59 (95% CI, 0.36-0.96) in regular users for less than 10 years, and 0.38 (95% CI, 0.16-0.92) in regular users for 10 years or more as compared with nonusers of vitamin E (p for trend = 0.004). In contrast, no significant associations were found for use of vitamin C or multivitamins. These results suggest that vitamin E supplementation could have a role in ALS prevention.

Intratympanic treatment of hearing loss with novel and traditional agents

As knowledge of the cellular and molecular pathophysiology behind otopathologies expands, the possibility exists of preventing sensorineural hearing loss and perhaps reversing the loss. Cellular and molecular mechanisms seem to be similar in hearing loss secondary to aging, drug ototoxicity, noise, or other mechanisms. A final common pathway may hinge upon apoptosis. It is likely that anti-apoptotic factors will increasingly be realized as an important intervention strategy for sensorineural hearing loss. Furthermore, it is also possible that mounting a staged attack at the various regions in the pathway leading to cellular damage using a combination of several protective substances such as steroids, antioxidants, neurotrophic factors, anti-apoptotic compounds, and mitochondrial enhancers may prevent hearing loss and even reverse it in some situations. This article has presented some of the molecular and cellular mechanisms for hearing loss and potential ways of treating them. In theory, the delivery of these medications to the inner ear transtympanically would decrease systemic side effects and be more target specific. Because most of the studies conducted to date have been animal studies, randomized, double-blind, placebo-controlled clinical trials would be necessary before the use of these therapies becomes common practice.

Amlodipine and carvedilol prevent cytotoxicity in cortical neurons isolated from stroke-prone spontaneously hypertensive rats

We previously reported that vitamin E prevents apoptosis in neurons during cerebral ischemia and reperfusion in stroke-prone spontaneously hypertensive rats (SHRSP). In this paper, we analyzed the effects of antihypertensives as well as vitamin E, which were added to neuron cultures after reoxygenation (20% O2) following hypoxia (1% O2). When added after hypoxia before reoxygenation, vitamin E conferred significant protection to neuronal cells. It was also shown that vitamin E conferred complete protection from neural cell death when added hypoxia and again before reoxygenation. At higher concentrations of vitamin E, strong neuroprotection was observed. Moreover, we verified that pretreatment with either amlodipine, carvedilol or dipyridamole consistently prevented cell death during hypoxia and reoxygenation (H/R). On the other hand, nilvadipine, a dihydropyridine-type calcium entry blocker, had no apparent effect on neuroprotection during H/R. The order of neuroprotective potency was vitamin E > dipyridamole > carvedilol > or = amlodipine > nilvadipine. In parallel experiments, we examined whether these antihypertensive agents were more effective when combined with vitamin E and dipyridamole. The results suggested that in our in vitro model system, antioxidants were the most important agents for the reduction of oxygen-free radical damage in cortical neurons. These findings suggest that amlodipine and carvedilol, with their antioxidant properties and antihypertensive activity, would be useful to inhibit neuronal cell death in the treatment of cerebrovascular stroke and neurodegenerative diseases in hypertensive patients.

Anticlastogenic effects of Aevitum intake in a group of chemical industry workers

The incidence of chromosome aberrations (CAs) was investigated in cultured lymphocytes of 109 styrene-, formaldehyde-, and phenol-exposed workers in comparison with 64 controls. There was a marked increase in the incidence of the structural chromosome aberrations in the first mitotic division metaphases of occupationally exposed workers (3.59 +/- 0.26 CAs/100 cells vs 1.47 +/- 0.14 in controls (P < 0.01). 22 occupationally-exposed workers were selected for the trial including 1-month administration of a drug Aevitum (100,000 U of retinol palmitate plus 0.1 g of alpha-tocopherol acetate dissolved in 0.2 ml of oil) at a daily dose of 1-2 capsules for 5 days a week. The frequency of chromosome aberrations before, after the administration of a cumulative Aevitum dose of 2.0, 4.0 and 8.0 ml, and 6 weeks after the cessation of vitamin intake was 5.68 +/- 0.63, 4.33 +/- 0.45, 2.67 +/- 0.34, 2.00 +/- 0.25, and 2.64 +/- 0.21 per 100 cells, respectively. Thus, Aevitum was found to cause a significant decrease in occupationally-induced chromosome damage in human lymphocytes.

Pharmacologic Manipulation of the Labyrinth with Novel and Traditional Agents Delivered to the Inner Ear

We describe the methodology and rationale behind the delivery of therapeutic medicines to the inner ear. The inner ear has long been impervious to pharmacologic manipulation. This is most likely the result of a protective mechanism called the blood-labyrinth barrier, whose function closely resembles that of the blood-brain barrier. This protective barrier impedes the clinician's ability to treat inner ear diseases with systemically administered medications. Since 1935, otolaryngologists have attempted to manipulate the inner ear with transtympanically injected medicines. Success has varied widely, but medicinal ablation of vestibular function can be achieved in this manner. Unfortunately, the auditory system is also at great risk from any medicine that is delivered to the inner ear via the middle ear. Over the past 10 years, significant improvements in drug delivery have allowed for more “titratable” treatment, which has reduced (but not eliminated) the risk of permanent hearing loss. In this article, we discuss both novel and time-tested methods of delivering medicines to the inner ear. We also review the classes of medications that alter inner ear function and the attendant risks of such treatments.

Delivery systems for antioxidant nutrients

The novel role of oxidants and antioxidants as part of cell signaling cascades has opened new areas of research in several disease states and their therapeutic strategies. For successful therapeutic manipulation of reactive oxygen species (ROS)-mediated cellular signaling pathways, it would necessitate control of the critical balance of oxidants/antioxidants in the target site by the antioxidant. Another way of controlling the critical balance is to avoid excessive generation of ROS from nutrients and/or drugs. From the viewpoint of controlling the balance between the oxidant and antioxidant status, this review focuses on the prodrug approach for delivery systems of vitamin E, a major antioxidant nutrient in the membrane, and on the reductive activation-independent delivery system of vitamin K hydroquinone by a prodrug approach, which can avoid excessive generation of ROS synchronized with the activation process of vitamin K.

The effect of dietary menhaden, olive, and coconut oil fed with three levels of vitamin E on plasma and liver lipids and plasma fatty acid composition in rats

The effect of dietary fats with varying degrees of unsaturation in the presence of different concentrations of vitamin E on tissue lipid levels was studied in rats. Rats were fed either menhaden oil, olive oil or coconut oil at 15% levels with either 0.1, 0.3 or 0.6 mg/g of vitamin E as alpha-tocopherol for four weeks. Rat serum and liver were analyzed for total cholesterol, HDL-cholesterol, triacylglycerol and phospholipids. In addition, fatty acid composition of serum lipids was also analyzed. Serum total cholesterol and triacylglycerol were significantly lower in rats fed menhaden oil than in those fed olive or coconut oil, while the HDL-cholesterol was significantly higher in serum of rats fed menhaden and olive oil than in those fed coconut oil. Levels of vitamin E in the diet had only a significant effect on serum cholesterol and liver phospholipids. The Pearson correlation coefficient showed a significant positive relationship between serum triacylglycerol and total cholesterol, and a negative correlation between triacylglycerol and HDL-cholesterol, and between total and HDL-cholesterol.In the liver, total cholesterol was significantly higher in rats fed coconut oil than in rats fed menhaden oil. Total liver phospholipids were lower in rats fed either coconut oil or olive oil compared to those fed menhaden oil, especially with higher levels of vitamin E intake. Higher levels of vitamin E in the diet appear to increase triacylglycerol and phospholipids in livers of rats fed menhaden oil. In the liver a significant negative correlation was observed between phospholipids and cholesterol. The type and degree of unsaturation (polyunsaturated fatty acids in menhaden oil, monounsaturated fatty acids in olive oil and saturated fatty acids in coconut oil) significantly affected plasma and tissue lipids.

Incorporation of alpha-tocopherol in marine lipid-based liposomes: in vitro and in vivo studies

Liposomes made from a natural marine lipid extract and containing a high polyunsaturated n-3 fatty lipid ratio were envisaged as oral route vectors and a potential alpha-tocopherol supplement. The behavior of vesicles obtained by simple filtration and of giant vesicles prepared by electroformation was investigated in gastrointestinal-like conditions. The influence of alpha-tocopherol incorporation into liposomes was studied on both physical and chemical membrane stability. Propanal, as an oxidation product of n-3 polyunsaturated fatty acids, was quantified by static headspace gas chromatography when alpha-tocopherol incorporation into liposome ratios ranged from 0.01 to 12 mol%. Best oxidative stability was obtained for liposomes that contained 5 mol% alpha-tocopherol. Compared to the other formulas, propanal formation was reduced, and time of the oxidation induction phase was longer. Moreover, alpha-tocopherol induced both liposome structural modifications, evidenced by turbidity, and phospholipid chemical hydrolysis, quantified as the amount of lysophospholipids. This physicochemical liposome instability was even more pronounced in acid storage conditions, i.e., alpha-tocopherol incorporation into liposome membranes accelerated the structural rearrangements and increased the rate of phospholipid hydrolysis. In particular, giant vesicles incubated at pH 1.5 underwent complex irreversible shape transformations including invaginations. In parallel, the absorption rate of alpha-tocopherol was measured in lymph-cannulated rats when alpha-tocopherol was administrated, as liposome suspension or added to sardine oil, through a gastrostomy tube. Alpha-tocopherol recovery in lymph was increased by almost threefold, following liposome administration. This may be related to phospholipids that should favor alpha-tocopherol solubilization and to liposome instability in the case of a high amount of alpha-tocopherol in the membranes. A need to correlate results obtained from in vitro liposome behavior with in vivo lipid absorption was demonstrated by this study.

Reduction of carbon tetrachloride-induced rat liver injury by IRFI 042, a novel dual vitamin E-like antioxidant

Carbon tetrachloride (CCl4 )-induced hepatotoxicity is likely the result of a CCl4 -induced free radical production which causes membrane lipid peroxidation and activation of transcription factors regulating both the TNF-alpha gene and the early-immediate genes involved in tissue regeneration. IRFI 042 is a novel vitamin E-like compound having a masked sulphydryl group in the aliphatic side chain. We studied the effect of IRFI 042 on CCl4 -induced liver injury. Liver damage was induced in male rats by an intraperitoneal injection of CCl4 (1 ml/kg in vegetal oil). Serum alanine aminotransferase (ALT) activity, liver malondialdehyde (MAL), hydroxyl radical formation (OH*), calculated indirectly by a trapping agent, hepatic reduced glutathione (GSH) concentration, plasma TNF-alpha, liver histology and hepatic mRNA levels for TNF-alpha were evaluated 48 h after CCl4 administration. Hepatic vitamin E (VE) levels were evaluated, in a separate group of animals, 2 h after CCl4 injection. A control group with vitamin E (100 mg/kg) was also treated in order to evaluate the differences versus the analogue treated groups. Intraperitoneal injection of carbon tetrachloride produced a marked increase in serum ALT activity (CCl4 = 404.61 +/- 10.33 U/L; Controls= 28.54 +/- 4.25 U/L), liver MAL (CCl4 = 0.67 +/- 0.16 nmol/mg protein; Controls= 0.13 +/- 0.06 nmol/mg protein), OH(7) levels assayed as 2,3-DHBA (CCl4 = 8.73 +/- 1.46 microM; Controls= 0.45 +/- 0.15 microM) and 2,5-DHBA (CCl4 = 24.61 +/- 3.32 microM; Controls= 2.75 +/- 0.93 microM), induced a severe depletion of GSH (CCl4 = 3.26 +/- 1.85 micromol/g protein; Controls= 17.82 +/- 3.13 micromol/g protein) and a marked decrease in VE levels (CCl4 = 5.67 +/- 1.22 nmol/g tissue; Controls= 13.47 +/- 3.21 nmol/g tissue), caused liver necrosis, increased plasma TNF-alpha levels (CCl4 = 57.36 +/- 13.24 IU/ml; Controls= 7.26 +/- 2.31 IU/ml) and enhanced hepatic mRNA for TNF-alpha (CCl4 = 19.22 +/- 4.38 a.u.; Controls= 0.76 +/- 0.36 a.u.). IRFI 042 (100 mg/kg, 30 min after CCl4 injection) blunted liver MAL (0.32 +/- 0.17 nmol/mg protein), decreased the serum levels of ALT (128.71 +/- 13.23 U/L), and restored the hepatic concentrations of VE (9.52 +/- 3.21 nmol/g tissue), inhibited OH* production (2,3-DHBA= 3.54 +/- 1.31 microM; 2,5-DHBA= 7.37 +/- 2.46 microM), restored the endogenous antioxidant GSH (12.77 +/- 3.73 mmol/g protein) and improved histology. Furthermore IRFI 042 treatment suppressed plasma TNF-alpha concentrations (31.47 +/- 18.25 IU/ml) and hepatic TNF-alpha mRNA levels (11.65 +/- 3.21 a.u.). The acute treatment with vitamin E failed to exert any protective effect against CCl4 -induced hepatotoxicity. These investigations suggest that IRFI 042 treatment may be of benefit during free radical-mediated liver injury.

Reactive oxygen metabolites, antioxidants and head and neck cancer

This manuscript will review the probable role of reactive oxygen metabolites (ROM) in the etiopathogenesis of head and neck cancer (HNC). Cancer is a heterogeneous disorder with multiple etiologies including somatic and germ-line mutations, cellular homeostatic disturbances, and environmental triggers. Certain etiologies are characteristic of HNC and include infectious agents such as the Epstein-Barr virus, the use of tobacco, and consumption of alcohol. A large body of evidence implicates ROM in tumor formation and promotion. ROM species are formed in the process of cellular respiration, specifically during oxidative phosphorylation. These ubiquitous molecules are highly toxic in the cellular environment. Of the many effects of ROM, especially important are their effect on DNA. Specifically, ROM cause a variety of DNA damage, including insertions, point mutations, and deletions. Thus, it is hypothesized that ROM may be critically involved in the etiology of malignant disease through their possible impact on protooncogenes and tumor suppressor genes. Additionally, empirical evidence suggests that ROM may also affect the balance between apoptosis and cellular proliferation. If apoptotic mechanisms are overwhelmed, uncontrolled cellular proliferation may follow, potentially leading to tumor formation. Thus, this manuscript will critically review the evidence that supports the role of ROM in tumorigenesis. ROM scavengers and blockers have shown both in vivo and in vitro effects of attenuating the toxicity of ROM. Such compounds include the antioxidant vitamins (A, C, and E), nutrient trace elements (selenium), enzymes (superoxide dismutase, glutathione peroxidase, and catalase), hormones (melatonin), and a host of natural and synthetic compounds (lazaroids, allopurinol, gingko extract). Thus, this paper will also review the possible benefit derived from the use of such scavengers/blockers in the prevention of HNC.

Electrophysiologic recovery after vitamin E-deficient neuropathy

A case report is presented of an electrophysiologic recovery from vitamin E-deficient neuropathy after treatment with water-soluble vitamin E in a patient with chronic hepatobiliary disease. The patient was a 64-year-old man who had experienced progressive difficulty in ambulation, with ataxia, over the previous 3 years. The symptoms were associated with pain, tingling sensation in the extremities, and reduced fine motor activity. The patient had chronic hepatobiliary disease, with recurrent cholangitis and external drainage of bile acid through a T-tube for more than 20 years. Vitamin E level was barely detectable (<0.5 mg/L). Sensory conduction was absent in both sural nerves. Other sensory and motor conduction studies in the upper and lower extremities showed decreased amplitude. The patient was treated with water-soluble vitamin E. After 4 months of therapy, his ambulation function improved, but pain and tingling sensation in both hands remained. Sensory nerve action potentials appeared in both sural nerves, and amplitudes of other sensory nerves were increased. In a second follow-up study after 9 months, all of the evaluated parameters in the nerve conduction studies, as well as the vitamin E level, were normal. The authors conclude that vitamin E-deficient neuropathy is reversible and electrophysiologic recovery can occur with water-soluble vitamin E therapy.

Smoking, plasma vitamins C, E, retinol, and carotene, and fatal prostate cancer: seventeen-year follow-up of the prospective basel study

BACKGROUND

Prostate cancer has one of the highest incidence rates of all cancers. Vitamin intake and tobacco use may have an impact on incidence and mortality, but epidemiologic evidence is scarce and inconsistent.

METHODS

Plasma vitamins C, E, retinol, and carotene were measured in 1971-1973 in 2,974 men working in Basel, Switzerland. In 1990, the vital status of all participants was assessed.

RESULTS

Two hundred and ninety men had died from cancer, including 30 with prostate cancer. On average, prostate cancer cases were 15 years older and smoked slightly more frequently than survivors. The mean values of plasma carotene, and of vitamin C, were nonsignificantly lower in prostate cancer cases than in survivors. After calculation of relative risk using the Cox model with exclusion of mortality during the first 2 years of follow-up, low vitamin E levels in smokers were related to an increased risk for prostate cancer. Relative risks of low vitamin C and carotene levels were about 1. A slightly but nonsignificantly increased risk was observed for low levels of retinol.

CONCLUSIONS

Given the profound implication if the risk of prostatic cancer could be reduced, the relationship with vitamin E and smoking requires further study.

Antioxidant transport by the human placenta

We investigated the transfer of three antioxidants - melatonin, S-adenosyl methionine (SAM) and various forms of vitamin E - across the term, normal human placenta. The transport technique involved the single, isolated placental cotyledon system in vitro. Melatonin crossed the placental rapidly, equally to the freely diffusible marker, antipyrine. There was no biotransformation of the agent. SAM was transferred slowly, similarly to passively transported L-glucose as a marker. There was a breakdown of SAM to at least one other derivative; the process appeared to be nonenzymatic. Vitamin E was transferred slowly, at a rate only 10% of L-glucose. The natural RRR (nonracemic) form of vitamin E was transported best. Free vitamin, rather than the acetate seems to be transferred best, a finding that will require further study.

The effect of Gingko biloba extract (Egb 761) as a free radical scavenger on the survival of skin flaps in rats. A comparative study

Free radicals may have a role in pedicle flap necrosis. We undertook this study to compare the effect of various antioxidants and scavengers of free radicals such as vitamin E, vitamin C, deferoxamine, and Gingko biloba extract (Egb 761) on McFarlane caudal-based dorsal rat flaps. Fifty rats were divided into five groups of 10 animals each. One group served as a control (saline) group. The remaining four groups were given vitamin C 340 mg/kg, deferoxamine 150 mg/kg, Egb 761 100 mg/kg, and vitamin E 20 mg/kg. The necrosed area of flap was significantly reduced in the deferoxamine (p < 0.001), Egb 761 (p < 0.001), and vitamin C (p < 0.05) groups compared with the control group. Vitamin E had no effect on distal flap necrosis (p = 0.20).

Prevention of diabetes-induced abnormal retinal blood flow by treatment with d-alpha-tocopherol

Hyperglycemia in diabetes mellitus has been shown to activate diacylglycerol (DAG)-protein kinase C (PKC) pathway in the vascular tissues, possibly altering vascular function. We have characterized the effects of vitamin E (d-alpha-tocopherol) on activation of PKC and DAG levels in retinal tissues of diabetic rats, and correlated its effects to retinal hemodynamics using video-based fluorescein angiography (VFA). Comparing streptozotocin-induced diabetic rats to controls, membranous PKC specific activities were increased by 71% (p < 0.05). Western blot analysis showed that the membranous PKC beta II isoform was significantly increased by 133 +/- 45% (p < 0.05). Intraperitoneal injection of d-alpha-tocopherol (40 mg/kg) every other day prevented the increases in membranous PKC specific activity and PKC beta II protein shown by immunoblots. Similar to PKC activities, total DAG levels were increased in the retina and were normalized by d-alpha-tocopherol treatment. Physiologically, abnormalities of retinal blood hemodynamics, as measured using VFA, which previously have been reported to be associated with increases of DAG and PKC levels in the diabetic rats, were prevented by d-alpha-tocopherol treatment in diabetic rats. The direct effect of d-alpha-tocopherol on total DAG and [3H]-palmitate incorporation into DAG were also examined using cultured bovine retinal endothelial cells (REC). Exposure of REC to 22 mM glucose for three days increased total DAG and [3H]-palmitate labeled DAG levels by 35 +/- 8% and 50 +/- 8%, respectively (p < 0.05). The presence of d-alpha-tocopherol (50 micrograms/ml) prevented the increase of both total DAG and [3H]-palmitate labeled DAG levels in cells exposed to 22 mM glucose. These findings suggested that the mechanism of the d-alpha-tocopherol's effect appears to be mediated by the normalization of the hyperglycemia-induced activation of the DAG-PKC pathway which leads to the normalization of abnormal retinal blood flow seen in diabetes mellitus.

Diet and nutrition in primary care. From antioxidants to zinc

This article reviews the role of diet in primary prevention based on current epidemiologic and clinical studies. Special consideration is given to circumstances which may require individualizing the dietary prescription. The role of dietary supplements in primary care is discussed. Particular emphasis is given to studies highlighting the clinical importance of specific minerals. Additionally, the practical application of antioxidant vitamins is presented in light of recent research findings.

Diet and prostate cancer: a case-control study

A case-control study, performed in two towns of Serbia (Yugoslavia) from 1990 to 1994, comprised 101 patients with histologically confirmed prostate cancer and 202 hospital controls individually matched by age (+/-2 years), hospital admittance and place of residence. Dietary information was obtained by using a standard questionnaire. After adjustment for possible confounders, risk factors for prostate cancer appeared to be the highest tertile of protein (odds ratio (OR) = 13.54, 95% confidence interval (CI) = 2.38-77.13), saturated fatty acid (OR = 3.63, 95% CI = 1.03-12.79), fibre (OR = 4.02, 95% CI = 1.38-11.73), and vitamin B12 intake (OR = 2.07, 95% CI = 1.08-3.97); a protective effect was found for the highest tertile of alpha-tocopherol (OR = 0.15, 95% CI = 0.05-0.53), calcium (OR = 0.37, 95% CI = 0.14-0.99) and iron intake (OR = 0.34, 95% CI = 0.12-0.95). There were significant (P < 0.05) linear trends in the odds ratios for alpha-tocopherol, vitamin B12, calcium and iron. According to logistic regression step by step analysis, risk factors for prostate cancer were dietary intake of retinol equivalent (OR = 1.64, 95% CI = 1.01-2.67) and vitamin B12 (OR = 1.87, 95% CI = 1.15-3.05), and a protective effect was found for dietary intake of iron (OR = 0.40, 95% CI = 0.27-0.58).

Oxidative stress and antioxidant therapy in Parkinson's disease

Parkinson's disease, known also as striatal dopamine deficiency syndrome, is a degenerative disorder of the central nervous system characterized by akinesia, muscular rigidity, tremor at rest, and postural abnormalities. In early stages of parkinsonism, there appears to be a compensatory increase in the number of dopamine receptors to accommodate the initial loss of dopamine neurons. As the disease progresses, the number of dopamine receptors decreases, apparently due to the concomitant degeneration of dopamine target sites on striatal neurons. The loss of dopaminergic neurons in Parkinson's disease results in enhanced metabolism of dopamine, augmenting the formation of H2O2, thus leading to generation of highly neurotoxic hydroxyl radicals (OH.). The generation of free radicals can also be produced by 6-hydroxydopamine or MPTP which destroys striatal dopaminergic neurons causing parkinsonism in experimental animals as well as human beings. Studies of the substantia nigra after death in Parkinson's disease have suggested the presence of oxidative stress and depletion of reduced glutathione; a high level of total iron with reduced level of ferritin; and deficiency of mitochondrial complex I. New approaches designed to attenuate the effects of oxidative stress and to provide neuroprotection of striatal dopaminergic neurons in Parkinson's disease include blocking dopamine transporter by mazindol, blocking NMDA receptors by dizocilpine maleate, enhancing the survival of neurons by giving brain-derived neurotrophic factors, providing antioxidants such as vitamin E, or inhibiting monoamine oxidase B (MAO-B) by selegiline. Among all of these experimental therapeutic refinements, the use of selegiline has been most successful in that it has been shown that selegiline may have a neurotrophic factor-like action rescuing striatal neurons and prolonging the survival of patients with Parkinson's disease.