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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Lipid peroxidation is a free radical process which is implicated in the formation of atherosclerosis. Vitamins C and E are important natural antioxidants which inhibit lipid peroxidation and a high intake of these vitamins, particularly vitamin E, is related to a reduced incidence of ischaemic heart disease. Hypertension is an independent risk factor for atherosclerosis and its relationship to antioxidant status is undetermined. In this study, we investigated free radical activity by measuring plasma malondialdehyde (MDA) using high-performance liquid chromatography (HPLC), vitamin C status measured as plasma ascorbic acid and vitamin E status measured as plasma lipid standardized alpha-tocopherol and erythrocyte alpha-tocopherol. We compared 28 patients with essential hypertension to 31 healthy subjects. Results showed that in comparison with the healthy subjects, the hypertensive patients had significantly higher plasma MDA levels (0.95 +/- 0.28 vs 0.69 +/- 0.21 mumol/l, mean +/- SD, p < 0.001) and significantly lower levels of plasma ascorbic acid (34.83 +/- 12.88 vs 51.76 +/- 13.34 mumol/L, p < 0.01). In addition, erythrocyte alpha-tocopherol concentration, which may reflect vitamin E protection in cell membranes, was significantly lower in hypertensive patients when compared with the normotensive controls (3.87 +/- 0.53 vs 4.82 +/- 1.01 mumol/l, p < 0.001), although plasma alpha-tocopherol levels were similar in the two groups (25.07 +/- 10.45 vs 23.96 +/- 6.07 mumol/l). Our results suggest that hypertensive patients may have increased lipid peroxidation and reduced protection from vitamins C and E. This may contribute to the propensity in such patients to develop atherosclerosis.
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PMID:Lipid peroxidation and antioxidant vitamins C and E in hypertensive patients. 882 28

Atherosclerosis is the leading cause of morbidity and mortality in western society. The most important risk factors for atherosclerosis include smoking, hypertension, dyslipidemia, diabetes and a family history of premature atherosclerosis. Several studies indicate that an increased plasma low density lipoprotein (LDL) cholesterol constitutes a major risk factor for atherosclerosis. Many data support a proatherogenic role for oxidized LDL, and its in vivo existence. The oxidative susceptibility of LDL is increased with established cardiovascular risk factors, such as diabetes, smoking and dyslipidemia. Supplementation with antioxidants such as ascorbate and alpha to copherol can decrease LDL oxidation as well as cardiovascular mortality and thus shows promise in the prevention of atherosclerosis
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PMID:Oxidized low-density lipoprotein and atherosclerosis. 890 49

Approximately 50% of the mortality in hemodialysis patients is due to cardiovascular disease. Antioxidant vitamins and carotenoids may be protective because oxidation of low-density lipoproteins appears to be a necessary prerequisite for the development of atherogenesis, and hemodialysis itself may stimulate the generation of oxygen reactive species. African Americans comprise a substantial proportion of dialysis patients because they have higher rates of hypertension, glomerulonephritis, and diabetic end-stage renal disease than do whites. The purpose of this cross-sectional study was to determine the plasma concentrations of antioxidant vitamins and carotenoids in hemodialysis patients and to investigate whether differences in these concentrations in the major racial or ethnic groups exist. Plasma concentrations of alpha- and gamma-tocopherol, carotenoids, and retinol were measured with HPLC and plasma vitamin C was measured with a spectrophotometric method in 109 white and African American hemodialysis patients. Dietary intakes of selected micronutrients were also compared by using data from a food-frequency questionnaire. Overall, plasma vitamin C and alpha-tocopherol concentrations were comparable but plasma carotenoid concentrations were lower than those reported for other populations. African American patients had significantly higher mean plasma concentrations of retinol (P < 0.04), lutein (P < 0.02), and total carotenoids minus lycopene (P < 0.04); whites had significantly higher mean plasma concentrations of alpha-tocopherol (P < 0.02), independent of age and plasma lipid concentrations. Diabetes comorbidity had an independent negative association with plasma beta-carotene concentration but was not associated with other measures.
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PMID:Racial group differences in plasma concentrations of antioxidant vitamins and carotenoids in hemodialysis patients. 906 38

Social class differences in health are seen at all ages, with lower socioeconomic groups having greater incidence of premature and low birthweight babies, heart disease, stroke, and some cancers in adults. Risk factors including lack of breast feeding, smoking, physical inactivity, obesity, hypertension, and poor diet are clustered in the lower socioeconomic groups. The diet of the lower socioeconomic groups provides cheap energy from foods such as meat products, full cream milk, fats, sugars, preserves, potatoes, and cereals but has little intake of vegetables, fruit, and wholewheat bread. This type of diet is lower in essential nutrients such as calcium, iron, magnesium, folate, and vitamin C than that of the higher socioeconomic groups. New nutritional knowledge on the protective role of antioxidants and other dietary factors suggests that there is scope for enormous health gain if a diet rich in vegetables, fruit, unrefined cereal, fish, and small quantities of quality vegetable oils could be more accessible to poor people.
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PMID:Socioeconomic determinants of health. The contribution of nutrition to inequalities in health. 947 37

The authors conducted a case-control study among the multi-ethnic population of Hawaii to examine the role of dietary soy, fiber, and related foods and nutrients on the risk of endometrial cancer. Endometrial cancer cases (n = 332) diagnosed between 1985 and 1993 were identified from the five main ethnic groups in the state (Japanese, Caucasian, Native Hawaiian, Filipino, and Chinese) through the rapid-reporting system of the Hawaii Tumor Registry. Population controls (n = 511) were selected randomly from lists of female Oahu residents and matched to cases on age (+/-2.5 years) and ethnicity. All subjects were interviewed using a diet history questionnaire that included over 250 food items. Non-dietary risk factors for endometrial cancer included nulliparity, never using oral contraceptives, fertility drug use, use of unopposed estrogens, a history of diabetes mellitus or hypertension, and a high Quetelet's index (kg/cm2). Energy intake from fat, but not from other sources, was positively associated with the risk of endometrial cancer. The authors also found a positive, monotonic relation of fat intake with the odds ratios for endometrial cancer after adjustment for energy intake. The consumption of fiber, but not starch, was inversely related to risk after adjustment for energy intake and other confounders. Similar inverse gradients in the odds ratios were obtained for crude fiber, non-starch polysaccharide, and dietary fiber. Sources of fiber, including cereal and vegetable and fruit fiber, were associated with a 29-46% reduction in risk for women in the highest quartiles of consumption. Vitamin A and possibly vitamin C, but not vitamin E, were also inversely associated with endometrial cancer, although trends were not strong. High consumption of soy products and other legumes was associated with a decreased risk of endometrial cancer (p for trend = 0.01; odds ratio = 0.46, 95% confidence interval 0.26-0.83) for the highest compared with the lowest quartile of soy intake. Similar reductions in risk were found for increased consumption of other sources of phytoestrogens such as whole grains, vegetables, fruits, and seaweeds. Ethnic-specific analyses were generally consistent with these results. The observed dietary associations appeared to be largely independent of other risk factors, although the effects of soy and legumes on risk were limited to women who were never pregnant or who had never used unopposed estrogens. These data suggest that plant-based diets low in calories from fat, high in fiber, and rich in legumes (especially soybeans), whole grain foods, vegetables, and fruits reduce the risk of endometrial cancer. These dietary associations may explain in part the reduced rates of uterine cancer in Asian countries compared with those in the United States.
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PMID:Association of soy and fiber consumption with the risk of endometrial cancer. 927 Apr 8

Consuming a diet rich in plant foods will provide a milieu of phytochemicals, nonnutritive substances in plants that possess health-protective benefits. Nuts, whole grains, fruits, and vegetables contain an abundance of phenolic compounds, terpenoids, pigments, and other natural antioxidants that have been associated with protection from and/or treatment of chronic disease such as heart disease, cancer, diabetes, and hypertension as well as other medical conditions. The foods and herbs with the highest anticancer activity include garlic, soybeans, cabbage, ginger, licorice, and the umbelliferous vegetables. Citrus, in addition to providing an ample supply of vitamin C, folic acid, potassium, and pectin, contains a host of active phytochemicals. The phytochemicals in grains reduce the risk of cardiovascular disease and cancer.
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PMID:Phytochemicals: guardians of our health. 933 91

We report here the first orally active, selenium-based antihypertensive agent, and we demonstrate its restricted CNS permeability using inductively coupled plasma/mass spectroscopy (ICP/MS) and operant behavioral analysis. The biochemistry and pharmacology of selenium are subjects of intense current interest. As a consequence of the redox chemistry of the selenium moiety, phenylaminoalkyl selenides possess the remarkable characteristic of propagating a cycle of turnover-dependent local depletion of reduced ascorbate when processed by the key enzyme of catecholamine metabolism, dopamine-beta-monooxygenase. ICP/MS analysis was used to determine the pharmacokinetic parameters for selenide compounds after i.v. administration to anesthetized rats. Analysis of the data using a two-compartment pharmacokinetic model established very rapid initial clearance and a short beta-elimination half-life from blood. We developed an oxidative procedure for digestion and processing of tissue samples in order to obtain ICP/MS data on the tissue distributions of Se-containing metabolites after the administration of selenide compounds. The results establish that aromatic ring hydroxylation of the selenides results in a marked reduction in brain levels of Se-containing metabolites. The comparative effects of selenide compounds on locomotor activity and operant behavior were then investigated, and the results fully corroborate the ICP/MS analytical results. The novel compound, 4-hydroxy-alpha-methyl-phenyl-2-aminoethyl selenide, exhibits both restricted CNS permeability and oral antihypertensive activity in spontaneously hypertensive rats. This compound is the first orally active selenium-based antihypertensive agent ever reported, and it possesses properties that are highly desirable in pharmacological agents being developed for treatment of chronic diseases such as hypertension.
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PMID:An orally active selenium-based antihypertensive agent with restricted CNS permeability. 935 59

Between 1986 and 1991, 29,584 persons took part in a randomized nutritional intervention trial in Linxian, China, an area whose residents had chronically low intakes of several nutrients and high rates of esophageal and gastric cardia cancer as well as stroke. Using a one-half replicate of a 2(4) factorial design, we randomized individuals to one of eight groups which received combinations of four supplements: retinol and zinc (factor A); riboflavin and niacin (factor B); vitamin C and molybdenum (factor C); and beta-carotene, alpha-tocopherol (vitamin E), and selenium (factor D). Deaths that occurred during 5 years of supplementation were ascertained and classified according to cause. At the end of the supplementation period, we measured blood pressure readings and determined the prevalence of hypertension. Participants who received factor D had reductions in total mortality (9%) and total cancer mortality (13%). These individuals also had the largest reduction in stroke mortality (relative risk = 0.91; 95% confidence interval = 0.76-1.07). End-of-trial hypertension, however, was not less prevalent among those receiving factor D. Our findings contrast with the larger reductions in stroke death and hypertension found in a parallel trial of Linxian subjects with esophageal dysplasia who received a multivitamin/mineral supplement, suggesting an effect largely derived from nutrients other than those received in the present study.
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PMID:Do nutritional supplements lower the risk of stroke or hypertension? 943 Feb 58

Low-density lipoprotein oxidation and antioxidant vitamins E and C were investigated in white-coat hypertension in comparison with sustained hypertension and normotension. We selected 21 sustained hypertensive subjects, 21 white-coat hypertensive subjects, and 21 normotensive subjects matched for gender, age, and body mass index. White-coat hypertension was defined as clinical hypertension and daytime ambulatory blood pressure <139/90 (subjects were also reclassified using 134/90 and 135/85 mm Hg as cutoff points for daytime blood pressure). Blood samples were drawn for lipid profile determination, assessment of fluorescent products of lipid peroxidation in native LDL, evaluation of susceptibility to LDL oxidation in vitro (lag phase and propagation rate), and determination of LDL vitamin E and plasma vitamins E and C contents. Compared with sustained hypertensive subjects, white-coat hypertensives had significantly lower fluorescent products of lipid peroxidation (15.4+/-3.4 versus 10.2+/-3 units of relative fluorescence/mg LDL protein, P<.05), longer lag phase (54+/-10 versus 88+/-10 minutes, P<.05), lower propagation rate (8.2+/-2.5 versus 5.95+/-2.1 nmol diene/min per mg LDL cholesterol, P<.05), higher LDL vitamin E content (8.3+/-1.1 versus 10.1+/-1.8 nmol/mg LDL cholesterol, P<.05), and plasma vitamin C content (40+/-13 versus 57+9 micromol/L, P<. 05). No significant difference was observed between white-coat hypertensive and normotensive subjects. The results did not change after reclassification of subjects. Our data show that white-coat hypertensive subjects do not show an enhanced propensity to LDL oxidation or reduction in antioxidant vitamins. Given the role of LDL oxidation in the development of atherosclerosis and that of vitamin E and C in protecting against it, these findings suggest that white-coat hypertension per se carries a low atherogenic risk.
Hypertension 1998 Feb
PMID:Low-density lipoprotein oxidation and vitamins E and C in sustained and white-coat hypertension. 946 Dec 31

Endothelial dysfunction is a key feature of diabetes mellitus and is thought to be the major cause of vascular complications associated with the disease. The vascular endothelium demonstrates impaired synthesis of vasodilators and increased release of procoagulants and vasoconstrictors, defects which theoretically could explain the increased incidence of atherosclerosis and hypertension found within this patient group. The pathways mediating endothelial cell layer dysfunction are unknown, although many candidates have been proposed. This review concentrates on the hypothesis that increased oxidative stress combined with abnormal plasma lipid composition leads to reduced synthesis of endothelial vasodilators and hence endothelial dysfunction. Free radical generation is undoubtedly raised in diabetes but the evidence for decreased antioxidant status is debatable. The role of antioxidant and lipid-lowering therapy is considered, but few studies have directly investigated the effect of treatment on vascular function. Concern arises from individual studies of vitamin E in diabetic animals which have proved deleterious. Current literature implies that a combination therapy of vitamin E and vitamin C may be beneficial, but this needs to be investigated further in both animal and human diabetes.
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PMID:Oxidative stress and lipids in diabetes: a role in endothelium vasodilator dysfunction? 954 38


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