Paula Zemel

Salt sensitivity in blacks. Salt intake and natriuretic substances.

Accumulating evidence suggests that hypertension in blacks is manifested in part by impaired renal excretion of salt. Consequently, this study was performed to determine if hypertensive and normotensive black subjects differ in their ability to generate known natriuretic substances. Fourteen normotensive and 11 hypertensive blacks were maintained on constant metabolic diets containing either 40 or 180 mmol of salt per day for 14 days each. During the last 4 days of each salt intake period, urine was collected for measurement of sodium, dopamine, and norepinephrine. On the last day of each 14-day dietary period, blood pressures were measured, blood was collected for measurement of plasma atrial natriuretic factor (ANF) and aldosterone, and urine was collected over 2 hours for measurement of prostaglandin E2 (PGE2). Both the normotensive and the hypertensive groups manifested salt sensitivity; then- mean arterial pressure rose by 7 ± 0.2 and 6 ± 0.2%, respectively, when salt intake was increased from 40 to 180 mmoJ/day. The hypertensive group exhibited decreased (p < 0.05) dopamme excretion as compared with the normotensive group for both dietary salt intakes. Plasma ANF levels increased (p < 0.05) in the hypertensive group, but not in the normotensive group, with increasing dietary salt. Plasma aldosterone and urinary norepinephrine and PGE2 were comparable in the two groups for both dietary salt Intakes. These data suggest that salt sensitivity is not unique to hypertensive blacks but occurs in normotensive blacks as well. Decreased renal production of dopamme may be a pathogenic factor in the development and maintenance of hypertension in blacks.

Altered platelet calcium metabolism as an early predictor of increased peripheral vascular resistance and preeclampsia in urban black women.

BACKGROUND Although preeclampsia is an important and relatively common medical problem, its pathophysiology remains unresolved and the search for a biochemical marker that precedes the hemodynamic abnormalities of preeclampsia continues. We designed a study to investigate the hemodynamic changes that characterize preeclampsia and to evaluate the metabolism of platelet intracellular calcium as a possible predictor of the development of preeclampsia. METHODS Hemodynamic measurements and spectrofluorometric determinations of the levels of intracellular calcium in platelets in the basal state and after stimulation with an agonist were performed in 48 nulliparous black women during each trimester of pregnancy. The data on the 14 women (29 percent) in whom preeclampsia developed were then compared with the data on the other 34, who served as normotensive controls. RESULTS There was no significant difference between the two groups in the basal levels of intracellular calcium at any time. In contrast, the levels measured after arginine vasopressin was administered during the first trimester indicated an exaggerated response in the group with preeclampsia as compared with the control group (1494 +/- 388 [+/- SEM] percent vs. 545 +/- 55 percent of base line; P less than 0.0002), which was sustained through the second and third trimesters. All but three of the women with preeclampsia had responses higher than the highest response among the controls. Platelet intracellular calcium responses to arginine vasopressin during the first trimester were a sensitive predictor of the subsequent development of preeclampsia (P less than 0.00009). Although vascular resistance was similar in the two groups during the first trimester, it subsequently decreased in the control group (P less than 0.02) but not in the group with preeclampsia. CONCLUSIONS Our findings indicate that preeclampsia is characterized by the absence of the normal pregnancy-related decrease in vascular resistance, which is preceded in most instances by an exaggerated response of platelet intracellular calcium to arginine vasopressin early in pregnancy. We therefore propose that an increase in the sensitivity of platelet calcium to arginine vasopressin can be used as an early predictor of subsequent preeclampsia.

Sexual dysfunction in the diabetic patient with hypertension

The prevalence of diabetes mellitus and hypertension in the United States is increasing partly because of the incidence of these diseases in the growing geriatric population. Diabetes and hypertension have been associated with sexual dysfunction in both men and women. Neuropathy, vascular insufficiency and psychological problems have been implicated in impotence, impaired ejaculation and decreased libido in men and in decreased vaginal lubrication, orgasmic dysfunction and decreased libido in women. Several investigations of women with diabetes suggest fewer reports of sexual dysfunction than have been reported by diabetic men. However, there have been few evaluations of sexual dysfunction in women and no standard methods for assessment. Antihypertensive agents, especially diuretics, sympathetic inhibitors and beta-blocking agents have been associated with sexual dysfunction due to autonomic and hormonal effects. An estimated 40 to 80% of diabetic hypertensives have reported sexual dysfunction in several investigations. Clearly, the diabetic hypertensive patient should be evaluated for sexual dysfunction, and appropriate therapy, including changes in medication or referral for sex counseling, should become routine in clinical care.

Relation between lipids and atherosclerosis: Epidemiologie evidence and clinical implications

Coronary artery disease (CAD) is the leading cause of death in most developed countries. Therefore, elucidation of risk factors and associated mechanisms for CAD has been a high priority. Data from the Framingham Heart Study and other large-scale epidemiologic studies have identified major risk factors associated with CAD, demonstrating the adverse effects of increased total and low-density lipoprotein cholesterol levels and the protective effect of high-density lipoprotein cholesterol. Other more recent investigations, including the Lipid Research Clinics Trial and the Helsinki Heart Study, have shown that lowering total cholesterol and raising high-density lipoprotein cholesterol significantly reduce the risk for CAD. Because hypertension is also a significant risk factor for CAD, the assumption has been that blood pressure reduction should offer significant benefits in terms of CAD risk. However, despite their antihypertensive efficacy, diuretics and beta blockers have failed to significantly reduce CAD morbidity or mortality. The adverse effects of these antihypertensive agents on lipid profiles, glucose metabolism and other metabolic parameters may account for their disappointing performance in reducing CAD morbidity and mortality. As a result, newer agents such as angiotensin-converting enzyme inhibitors and calcium antagonists that appear to be free of such adverse effects have garnered considerable attention for their potential to reduce CAD risk.

Role of Nutrition in Black Hypertension: Calcium and Other Dietary Factors

A number of studies have shown that, on average, blacks in the Western Hemisphere have higher blood pressure than blacks from sub-Sahara Africa (2,77,92,123). Considerable regional variations in blood pressure also exist among blacks in the Western Hemisphere (6,42,49,90). This geographical heterogeneity in the prevalence of hypertension in various black populations around the world suggests that environmental factors play a critical role in determining the prevalence of hypertension in blacks (90). The importance of environment in contributing to the prevalence of hypertension in blacks is reinforced by the observation that when rural Africans undergo changes to more urban, Western lifestyles and diets, blood pressure increases (2,23,90,93, see Chapter 7, this volume). The information in this chapter examines one important environmental factor, nutrition, and its role in contributing to high blood pressure in urbanized, Westernized blacks (Table 8.1).

Effects of magnesium supplementation on erythrocyte cation transport in diuretic-treated hypertensives

Abstract Magnesium (Mg) deficiency increases vascular resistance in rats, and limited evidence suggests that Mg supplementation may reduce blood pressure, possibly due to activation of Na/K-ATPase and/or reduction of intracellular calcium. Further, treatment with thiazide and loop diuretics results in Mg depletion which may adversely affect cellular cation metabolism. Consequently, the present study was conducted to determine if such diuretic-induced alterations are preventable by Mg supplementation. Eleven diuretic-treated hypertensive patients completed a double blind randomized study with a 2-week single blind placebo period followed by 12 weeks on either placebo ((n=5) or 40 mEq Mg as Mg-Aspartate-HCl (n=6), and blood was collected for determination of erythrocyte intracellular cation levels and membrane Na/K- and Ca-ATPase activity. Mg supplementation resulted in increases (p

Use of statistical techniques in nutrition education research publications

Abstract We identified sources of statistical information and categorized statistical techniques used in research published in the Journal of Nutrition Education (JNE) and compared the statistical techniques to those used in nutrition and food science journals. We also evaluated the level of statistical knowledge required to interpret JNE research. We examined 101 JNE research articles published from 1980–86 and 120 research articles from a sample of nutrition and food science journals. The latter were selected based on frequency of citation in the JNE articles. Descriptive statistics, Pearson r , Students t -test, one-way ANOVA, and measures of reliability were used in at least 20% of both JNE and nutrition and food science research articles. The JNE articles used factor analysis, item analysis, and measures of reliability and validity significantly more often than did the nutrition and food science articles. JNE research articles used more complex statistical techniques, which required a higher level of statistical knowledge, and provided a more thorough explanation of the statistics used than did the nutrition and food science research. This study provides a baseline for evaluating trends in use of statistics in nutrition education research, it may help improve the communication of research needs and results between researchers and practitioners, and it can help academic programs in nutrition education to evaluate their curricula.