Interactive influences of ethnicity, gender and parental hypertension on hemodynamic responses to behavioral challenge.

To determine the independent and interactive influences of ethnicity, gender and parental hypertension on the magnitude and patterning of hemodynamic responses to standardized laboratory stressors, 112 normotensive, young adult African-American and Caucasian subjects (56 women, 56 men) completed a four-task protocol: three psychological stressors (the Stroop Color Word task, mental arithmetic and mirror tracing) and the forehead cold pressor test. Blood pressure (BP), heart rate (HR) and impedance derived measures of cardiac pre-ejection period and stroke volume were measured at rest and during each task; calculated indices of cardiac output and total peripheral resistance were also computed. Women responded to the psychological stressors with significantly larger increases in HR and cardiac output, less change in total peripheral resistance and greater attenuation of cardiac pre-ejection period than did men; however, blood pressure responses did not vary by gender, ethnicity or parental history of hypertension. Across tasks, African Americans showed larger elevations in total peripheral resistance than did Caucasians; conversely Caucasian subjects showed a more pronounced cardiac responsivity to stress, as evidenced by an elevated cardiac output and concomitant decrease in cardiac pre-ejection period, compared to their African-American counterparts. The ethnic differences in reactivity to psychological stressors were more apparent among males, while the gender differences were generally more pronounced among African Americans. Finally, the cold pressor test elicited larger increases in systolic blood pressure (SBP) among Caucasian subjects with family history positive (FH+), relative to family history negative (FH-) subjects, and also caused a greater reduction in HR among males compared to females.

The role of socioeconomic status and serum fatty acids in the relationship between intake of animal foods and cardiovascular risk factors.

Little is known regarding the relationship of serum fatty acids to cardiovascular risk factors in Nigerian populations. Civil servants with higher socioeconomic status (SES) in Nigeria appear to be in cultural transition toward a more Westernized lifestyle. For this study the food intakes of 397 civil servants were estimated from two 24-h recalls. Fatty acids in serum total lipids were measured in both absolute weight concentration and percentage composition. Daily meat intake was 43.5 g, and fish intake was 70.5 g. The intakes of meat, eggs, and milk were higher in high SES Nigerians than in low SES Nigerians. The concentration of total fatty acids (TFA, the sum of 12 serum fatty acids) was also higher in high SES men and women, as compared with low SES men and women (2064, 2060, 1831, and 1776 mg/L, respectively). There were significant direct associations between meat intake and serum level of arachidonic acid, and between fish intake and serum levels of eicosapentaenoic acid and docosahexaenoic acid. TFA was positively associated with cholesterol, low-density-lipoprotein cholesterol (LDLc), and triglycerides across gender and SES groups after adjustment for body mass index, fasting insulin level, and age. Nigerian women were compared with two groups of American women. We concluded that fatty acids in absolute weight concentration reflected the amount of fat intake. The level of TFA was directly related to cardiovascular risk factors in Nigerians. Follow-up of such populations in cultural transition can facilitate the understanding of the true roles of animal food intake in the early evolution of atherosclerosis.

Absence of enhanced sympathoadrenal activity and behaviorally evoked cardiovascular reactivity among offspring of hypertensives.

To determine whether offspring of hypertensives show enhanced sympathetic nervous system activity, we evaluated several indices of sympathoadrenal activation and cardiovascular responsiveness to behavioral stimuli among 90 normotensive, young adult men having either one or two hypertensive parents (PH+(-), PH++) or normotensive parents only (PH--) (n = 30/group). Measurements included heart rate (HR) and blood pressure (BP) reactions to three mental stressors (the Stroop test, mental arithmetic, mirror tracing), a cold pressor test, postural adjustment (60 degrees upright tilt), isometric exercise and bicycle ergometry, as well as the 24-h excretion of catecholamines (epinephrine [E], norepinephrine [NE]) and venous plasma catecholamine concentrations, both at rest (seated and supine) and in response to the Stroop test and upright tilt. The three groups did not differ in age, education, body mass index (BMI), estimated aerobic fitness, resting HR, cardiac preejection period (PEP) and PEP:LVET (left ventricular ejection time) ratio, 24-h Na or K excretion, or fasting lipids, insulin or plasma renin activity. Resting systolic and diastolic BP varied as a function of parental hypertension, and were significantly higher in PH++ than among PH-- subjects (P < .05). No significant group difference was observed on any measure of plasma or urinary catecholamines, nor did offspring of hypertensives (PH++ or PH+-) showed greater HR or BP reactions than PH-- subjects to any of the several laboratory challenges. In sum, we find no evidence of enhanced sympathetic activity or heightened cardiovascular responsiveness among normotensive young adults who are familially predisposed to essential hypertension.

Family history studies in hypertension research. Review of the literature.

Reviewed in the present article are over 150 family history studies of essential hypertension. By comparing normotensive individuals with and without a family history of hypertension, these investigations seek to identify potential pathophysiologic factors that predate the development of high blood pressure. The research literatures summarized here represent four general areas: 1) cellular salt transport mechanisms, 2) dietary sodium, intravascular volume, and renal function, 3) cardiovascular morphology and physiology, and 4) cardiovascular reactivity. There is strong evidence of early cardiac morphologic changes (greater left ventricular wall thickness and mass) and altered peripheral vascular capacity and responsivity to pressor stimuli among normotensive individuals with a positive family history. In contrast, cardiac output, sodium consumption, intravascular volume, and cardiovascular responses to isometric exercise and standing do not differ in persons with and without a family history of hypertension. Other articles are characterized by inconsistent results, which may be a reflection of the heterogeneity of essential hypertension, but also may be due to methodological weaknesses. The latter include failure to confirm the blood pressure status of ostensibly hypertensive or normotensive family members and the use of relatively weak study designs (eg, where a positive history is defined by a single, hypertensive first-degree relative).

Number-related discrimination and summation by squirrel monkeys (Saimiri sciureus sciureus and S. boliviensus boliviensus) on the basis of the number of sides of polygons.

In Experiment 1, with the number of sides or angles of irregular polygons as cues, programmed training, and a 90% correct criterion (36 of 40), 2 squirrel monkeys' (Saimiri sciureus sciureus and S. boliviensus boliviensus) best performances were to discriminate heptagons from octagons, a 3rd's best was hexagons from heptagons, and a 4th's best was pentagons from heptagons. In Experiment 2, on most trials 2 polygons on one or both discriminanda had to be summed to determine which discrimination had the total fewer sides. Only 1 monkey met criterion (27 of 30) on the 2 tasks, 6 vs. 8 and 7 vs. 8 sides, but the other 3 performed better than chance on the 6 vs. 8 task. We conclude that previous studies of animals' discrimination of polygons in terms of complexity were minimally relevant to this work, and counting and subitizing were rejected in favor of a prototype-matching process to explain our monkeys' performances.