Blood pressure and echocardiographic measures in children: the Bogalusa Heart Study

M mode echocardiograms were obtained from 654 healthy subjects, 7 to 22 years of age, whose diastolic blood pressure levels remained in the same height-, race-, and sex-specific decile during two biannual examinations. Echocardiographic measures of heart size, obtained according to the recommendations of the American Society for Echocardiography, were compared across the entire systolic and diastolic blood pressure distributions. Echocardiographic indexes of left heart size varied as a function of both blood pressure levels and body size. Significant positive correlations were present between systolic blood pressure and different measures of left ventricular size. Left ventricular wall thickness in systole correlated with systolic blood pressure (r = .42, p less than .0001), and persistence of this relationship was noted after adjustment for body size. Left ventricular wall thickness in diastole correlated with blood pressure before adjustment (r = .31, p less than .0001), but the relationship was not significant after adjustment for body size. The ratio of left ventricular thickness to chamber size (systole) correlated with systolic blood pressure levels both before and after adjustment for body size (r = .20 and r = .22, p less than .001). Male subjects of both races demonstrated significantly higher adjusted left ventricular mass, left ventricular wall thickness, and left ventricular chamber size. Adjusted left ventricular wall stress was significantly related to both systolic (r = .14) and diastolic blood pressure levels (r = .14, p less than .001). Measures of left ventricular wall thickness increased throughout the entire blood pressure distribution, indicating a consistent trend rather than a threshold effect seen only in the highest blood pressure groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Plasma lipid concentrations in nondiabetic African American adults: associations with insulin resistance and the metabolic syndrome

Despite higher rates of cardiovascular disease, African Americans have a more favorable lipid profile. The purpose of the study was to examine the association between plasma lipid concentrations and insulin resistance in African Americans and to determine if insulin resistance is present at a lower triglyceride (TG) threshold than is used for metabolic syndrome criteria. Data were examined on 185 nondiabetic African American men (n = 61) and women (n = 124), mean age, 39.8 years. Measurements included blood pressure, anthropometrics, oral glucose tolerance test, and insulin sensitivity (M) by insulin clamp. The relationship between lipids and insulin sensitivity was analyzed by correlation analysis and by comparing TG levels among tertiles of M. Despite relatively low mean (+/- SD) TG level (87.8 +/- 55.2 mg/dL), there were statistically significant correlations of M with TG (r = -0.23, P < .002), high-density lipoprotein cholesterol (HDL-C; r = 0.19, P < .01), and TG/HDL-C ratio (r = -0.23, P < .002). The correlations were strongest in men. Subjects with TG in an intermediate range (110-149 mg/dL) had insulin resistance equivalent to that of the high-TG group (>/=150 mg/dL). In African Americans, TG levels below the current metabolic syndrome threshold criterion are associated with insulin resistance.     

Serum apolipoprotein E in children and adolescents: the Bogalusa Heart Study

Serum apolipoprotein (apo) E levels and its relationship to lipids and lipoprotein cholesterol fractions were examined in a random subsample (n = 561) of children and adolescents (7 to 17 years of age) from a total biracial community. Mean (+/- SD) levels of apo E were higher in blacks (males 4.8 +/- 1.8 mg/dL; females 5.2 +/- 1.8 mg/dL) than in whites (males 3.9 +/- 1.2 mg/dL; females 4.3 +/- 1.0 mg/dL) irrespective of sex (P less than .001). The black-white difference in apo E persisted after controlling for the covariates: sexual maturation, age, adiposity, cigarette smoking, alcohol use, and oral contraceptive use (P less than .001). A sex differential (females greater than males, P less than .01) for apo E was seen in both racial groups. Apo E levels were inversely associated with age (P less than .01) and sexual maturation (P less than .05) only in white males. Apo E related positively and significantly to total cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol fractions (HDL2-C and HDL3-C) in certain race-sex groups. Race, HDL2-C, triglycerides (very-low density lipoprotein cholesterol), HDL3-C, and sex were identified as predictor variables for apo E, in that order, and accounted for 21% of its variability in serum. It is conceivable that the observed race-sex differences in apo E may be related to apo E-HDL subfraction, which is thought to participate in the reverse cholesterol transport.     

Longitudinal serum lipoprotein changes in white males during adolescence: the Bogalusa Heart Study

Determinants of follow-up levels of low-density lipoprotein-cholesterol (LDL-C), high-density lipoprotein-cholesterol (HDL-C) and the ratio of LDL-C to HDL-C were analyzed in a longitudinal study. White boys (n = 81) aged 11 to 12 years, when examined in 1973-1974 (year 1) were reexamined in 1978-1979 (year 6) at ages 16 to 17 years. During follow-up, mean levels of LDL-C increased from 87.6 mg/dL to 89.8 mg/dL, mean levels of HDL-C decreased from 67.0 mg/dL to 48.4 mg/dL and the mean LDL-C/HDL-C ratio increased from 1.45 to 2.12. Cross-sectional associations between the serum lipoproteins and weight, triceps skinfold thickness, and ponderosity (wt/ht3) were stronger in year 6 than in year 1. A persistence of ranks was observed between year 1 and year 6 for LDL-C (r = 0.61), HDL-C (r = 0.51), and LDL-C/HDL-C (r = 0.50). Multiple linear regression indicated that year 6 LDL-C levels were positively related to year 1 LDL-C, year 1 Tanner stage (an indication of sexual maturation), and the change in skinfold thickness during follow-up. Follow-up LDL-C/HDL-C was related both to change in height (negatively) and to change in weight (positively), after controlling for year 1 LDL-C/HDL-C. These longitudinal findings were similar to those obtained from earlier cross-sectional analyses and were further verified on an independent cohort of white boys also followed for five years (1976-1977 through 1981-1982).(ABSTRACT TRUNCATED AT 250 WORDS)     

Fasting plasma glucose and insulin levels and their relationship to cardiovascular risk factors in children: Bogalusa Heart Study

Plasma glucose and insulin levels were determined in a total biracial community of 3313 children, ages 5-17 years. Black children have significantly higher insulin and lower glucose levels than white children of comparable age and sex. Children of diabetic parents have elevated levels of age- and weight-adjusted fasting cholesterol. Moderate tracking (r = 0.31) of glucose levels over a 3-year period was seen. Insulin levels, however, track well (r = 0.36) only in older children (ages 9-14 years at initial examination). Fasting insulin levels are positively related to measures of obesity, systolic and diastolic blood pressure, triglyceride, beta-lipoprotein cholesterol and pre-beta-lipoprotein cholesterol levels. In addition, insulin levels are negatively related to alpha-lipoprotein cholesterol levels. Fasting glucose levels are positively related to systolic and diastolic blood pressure, triglycerides, pre-beta-lipoprotein cholesterol, and obesity levels. The relationship of plasma glucose and insulin levels to the traditional cardiovascular risk factors in children emphasizes the importance of subtle abnormalities in carbohydrate metabolism in the early natural history of cardiovascular disease.     

Aldosterone and aldosterone: renin ratio associations with insulin resistance and blood pressure in African Americans

African Americans have more hypertension and hypertension-related morbidity than whites. Aldosterone, in presence of a high salt intake, contributes to hypertension and tissue injury. Inappropriately elevated aldosterone levels could explain this racial disparity. Our study was conducted to determine if aldosterone is associated with elevated blood pressure (BP) or insulin resistance, independent of obesity. A study was conducted on 483 young adult African Americans without cardiovascular or renal disease. Measurements included anthropometrics, BP, lipids, glucose, insulin, aldosterone, and renin. Urine sodium and potassium estimated sodium intake. The cohort was stratified by tertiles of aldosterone and tertiles of aldosterone/renin ratio (ARR). Average urine sodium/potassium ratio was >3.0 in all groups. Insulin resistance, estimated by homeostasis model, was lowest in the low aldosterone group (geometric mean 1.5 [0.6, 2.2]) compared with the high aldosterone group (1.7 [0.9, 2.7], P < .01). Adjusted analyses detected a significant association of aldosterone with insulin resistance, independent of other variables. BP was significantly higher in the high ARR group compared with low and mid ARR groups (P < .01). The significant association of ARR with BP with high dietary sodium suggests that insufficiently suppressed aldosterone may contribute to BP sensitivity to sodium in African Americans.     

Beta-adrenergic receptor genes are associated with arterial stiffness in black and white adults: the Bogalusa Heart Study

BACKGROUND: Sympathetic nervous activity, which is regulated by the beta-adrenergic receptor (beta-AR), is an important determinant of the arterial wall-stiffening process. This study examines the genetic influence of beta-AR gene polymorphisms (beta(1)-AR Arg389Gly, beta(2)-AR Arg16Gly, and beta(3)-AR Trp64Arg) on arterial stiffness in black and white young adults. METHODS: The study cohort included 366 black and 891 white adults, aged 19 to 44 years, enrolled in the Bogalusa Heart Study. Aorta-femoral pulse-wave velocity (af-PWV) was measured by echo-Doppler in a subsample (n = 614). RESULTS: Pulse pressure and heart rate were significantly associated with af-PWV in both races, but not with the three polymorphisms. The af-PWV values differed significantly among the beta(1)-AR Arg389Gly genotype groups in whites (P = .007) and in the total sample (P = .005), with those who were homozygous for Gly389 showing higher values than those who were homozygous for Arg389, after adjusting for cardiovascular risk factors. The beta(3)-AR Arg64 allele was associated with higher af-PWV values in blacks (P = .022) and in the total sample (P = .015). The beta(2)-AR Arg16 allele was associated with af-PWV only in blacks (P = .020). In multivariate regression analysis for the total sample, age, pulse pressure, heart rate, beta(1)-AR Arg389Gly, beta(3)-AR trp64Gly, and smoking status were, in descending order, associated with af-PWV. Furthermore, af-PWV values significantly increased with the increasing number of beta(1)-AR Gly389, beta(2)-AR Arg16, and beta(3)-AR Arg64 alleles (P for trend = .0003). CONCLUSIONS: These results indicate that the beta-AR gene polymorphisms influence arterial stiffness in black and white young adults in an additive manner.     

Influence of persistent obesity in children on cardiovascular risk factors: the Bogalusa Heart Study

The relationship between body fat indexes, lipid and lipoprotein levels, and blood pressure was studied in 2230 children, each examined during 1973, 1976, and 1978. The children were grouped with the use of seven percentile (P) intervals of triceps skinfold thickness that were specific for race, sex, and age; cardiovascular risk factor variables were assessed over time. Of the 238 children initially in the lowest P group (less than 15P), 44% remained there, and 65% had skinfold thicknesses below 30P on the three occasions. Of the 352 children in the highest P group (greater than or equal to 85P), who were considered to be very obese, 39% remained at this level while 69% remained at 70P or greater. Of the 366 considered to be obese (greater than or equal to 70, less than 85%P), 38% remained at or above 70P. At baseline, children in the seven groups differed in weight, ponderosity (wt/ht3), systolic and diastolic blood pressures, serum triglyceride levels, and pre-beta- and beta-lipoprotein cholesterol levels. Pairwise comparison of data from children in each of the six other groups with those from children in the middle range (greater than or equal to 40, less than 60P) showed that the obese and very obese children had significantly higher systolic blood pressures (p less than .05), while only those in the highest P group had significantly greater diastolic blood pressures (p less than .05). These differences increased and diverged over time. Those in the obese and very obese groups showed a striking drop over time in alpha-lipoprotein cholesterol levels and increases in pre-beta-lipoprotein cholesterol levels and systolic blood pressure. Triglyceride levels decreased over time for the lowest and middle range groups but remained at higher levels in obese and very obese children. There was a strong tendency for tracking (remaining in the same P group over time) in lean, obese, and very obese children. Those who tracked showed definite differences in risk factor variables at the baseline level and over time when compared with the middle range group. Since consistent obesity in early life enhances cardiovascular risk, the measurement over time of skinfold thickness in children is a useful method to detect the potential for adult cardiovascular disease.     

Serum lipoprotein profile in children from a biracial community: the Bogalusa Heart Study.

Serum lipoprotein profiles in 3182 children, ages 5-14 years, were studied in a biracial community as part of the Bogalusa Heart Study to describe the early natural history of atherosclerosis. White and black children showed similar mean levels of beta-lipoproteins. Pre-beta-lipoprotein levels, however, were significantly higher in white shildren, while significantly higher levels of alpha-lipoprotein were found in black children. Girls had generally higher levels of beta- and pre-beta-lipoprotein and lower levels of alpha-lipoprotein than boys, although the differences were not significant at each age group. With age there was little change in alpha-lipoprotein levels, a significant increase in pre-beta-lipoprotein levels and a slight but significant decrease between 11 and 14 years in beta-lipoprotein levels. The correlation of alpha-lipoprotein was negative with beta-lipoprotein and, to a greater extent, with pre-beta-lipoprotein. The above inverse relationships were significantly greater in white children than in black children, suggesting differences in lipoprotein profiles in the two groups. Lipoprotein values from a total community study are now available for comparison with the currently recommended upper normal limits for lipoproteins. Since only a very small percentage of children could be considered as hyperlipoproteinemic by those specific levels in this community, we suggest that distributions and percentiles be used to evaluate children for hyperlipoproteinemia.     

Insight into a bad omen for white men: coronary artery disease--the Bogalusa Heart Study

Clinical experience of diagnostic and interventional procedures, including cardiac surgery, indicates a greater prevalence of coronary heart disease in white men than in other race-gender groups. Studies of children and young adults in the Bogalusa Heart Study have provided evidence that might account for this race-gender contrast. A variety of anthropometric and metabolic parameters influencing serum lipid and lipoprotein levels places white boys and young white men selectively at high risk for the development of atherosclerotic coronary artery disease. Obesity and greater central body fat, subtle aberrations in carbohydrate-lipid metabolic relations and variability in sex hormone profiles appear to underlie a trend to adverse lipoprotein changes in white men. A lower high-density lipoprotein cholesterol level and apolipoprotein A-l at puberty and a dramatic increase of low-density lipoprotein cholesterol are seen in young white men; such adverse changes identify them to be at greater risk. It is noteworthy that children whose fathers had myocardial infarction tend to be white. These children also have relatively high ratios of apolipoprotein B/apolipoprotein A-l and apolipoprotein B/low-density lipoprotein cholesterol. Studies of risk factors in children emphasize their importance in the early natural history of coronary artery disease. These findings show the need for beginning prevention of adult heart disease in childhood.     

Plasma leptin concentrations and obesity in relation to insulin resistance syndrome components among school children in Taiwan--The Taipei Children Heart Study

OBJECTIVE: Leptin, an adipose tissue-derived product of the obesity (OB) gene, is an important regulator of energy metabolism and may be associated with the occurrence of insulin resistance and diabetes in humans. The purpose of this study was to evaluate the association of plasma leptin concentration with obesity and the components of insulin resistance syndrome (IRS) among school children in Taiwan. METHODS: After multistage sampling of 85 junior high schools in Taipei, we randomly selected 1,264 children (617 boys and 647 girls) aged 12-16y. Obesity measurements included body mass index (BMI) and waist-to-hip circumference ratio (WHR). We calculated an IRS summary score for each individual by adding the quartile ranks from the distribution of systolic blood pressure (BP), serum triglyceride (TG), HDL-cholesterol (inverse), and insulin levels. RESULTS: Boys had a higher BMI and WHR, BP and IRS score and lower leptin, insulin, TG and HDL-C levels than girls. BMI, WHR and plasma leptin levels were significantly associated with the IRS summary score and each of its components in both genders. Children with higher plasma leptin levels (> 75th percentiles) have significantly higher BP, TG, insulin levels and IRS score than children with low leptin levels. The associations between plasma leptin level and the IRS components and score were still significant after adjusting for BMI in boys, but less so in girls. In both genders, after adjusting for WHR, plasma leptin levels were still significantly associated with the IRS components and summary score (P< 0.001). The final model that included the standard covariates, BMI and leptin, but not WHR, was the most predictive of the IRS summary score among school children. CONCLUSIONS: Insulin resistance syndrome in childhood, characterized by high blood pressure, dyslipidemia, and hyperinsulinemia, may be an early marker of cardiovascular risk. From the present BMI and leptin in combination are the most predictive markers of insulin resistance syndrome among school children in Taiwan.     

Plasma renin and risk of cardiovascular disease and mortality: the Framingham Heart Study.

AIMS: Previous studies relating plasma renin to cardiovascular disease (CVD) and mortality yielded conflicting results. We related plasma renin to incidence of CVD and mortality in 3408 individuals (mean age 59; 53% women) and in a hypertensive subset (n = 1413). METHODS AND RESULTS: On follow-up (mean 7.1 years), 176 participants (122 hypertensives) developed CVD and 215 individuals (127 hypertensives) died. Overall, log-renin was associated with mortality [multivariable-adjusted hazards ratio (HR) per SD increment: in whole sample, 1.14, 95% confidence interval (CI) 1.00-1.30, P = 0.046; hypertensives, 1.16, 95% CI 1.00-1.35, P = 0.046], but relations varied over time (P < 0.02). Log-renin was associated with mortality at 2.5 years of follow-up (HR per SD increment: whole sample at 2.5 years, 1.23, 95% CI 1.04-1.45; hypertensives at 2 years, 1.28, 95% CI 1.06-1.54), but not during longer follow-up (HR per SD increment at 5 years: whole sample, 1.02, 95% CI 0.80-1.29; hypertensives, 0.98, 95% CI 0.74-1.30). The time-dependent relation of renin and mortality risk was maintained upon excluding participants with prevalent CVD. Renin was not associated with CVD incidence (HR per SD increment log-renin: whole sample, 0.99, 95% CI 0.85-1.14; hypertensives, 0.96, 95% CI 0.82-1.12). CONCLUSION: Higher plasma renin was associated with greater short-term mortality but not with CVD incidence in the community.     

Interobserver reproducibility of heart rate variability in children (the Bogalusa Heart Study)

Changes in time and frequency domain measures of heart rate variability appear to correlate with morbidity and mortality in patients with congenital heart disease. This study demonstrates that these measures are highly reproducible in children, a finding that has been previously described only in adults.     

Obesity--a critical issue in preventive cardiology: the Bogalusa Heart Study

Obesity has become a major public health problem in the United States, with a marked upward trend occurring over the past three decades. It plays a critical role in the development of cardiovascular risk factors that mediate the evolution of asymptomatic cardiovascular disease. Longitudinal observations of children, adolescents, and young adults enrolled in the Bogalusa Heart Study show that obesity persists over time and is linked to the clustering of components of metabolic syndrome including hyperinsulinemia/insulin resistance, dyslipidemia, and hypertension, thereby creating a long-term burden of cardiovascular risk beginning in childhood. This burden is associated with subclinical and adverse structural and functional changes of the cardiovascular system in youth. Ultimately, these changes can result in morbidity from disease, as exemplified in the Framingham Heart Study. Obesity is governed by the interplay of both genetic and environmental factors. Unlike genetic factors, lifestyle behaviors are amenable to modification. Since obesity is so widespread and underlying cardiovascular disease is so prevalent, health education beginning in childhood is suggested as an approach to prevention.     

Childhood blood pressure predicts adult microalbuminuria in African Americans,but not in whites: the Bogalusa Heart Study

BACKGROUND: Microalbuminuria is considered as a strong predictor of cardiovascular diseases. However, limited information is available for childhood blood pressure (BP) levels and microalbuminuria in adulthood. METHODS: This study examined 2,122 individuals enrolled in the Bogalusa Heart Study as children, aged 5 to 17 years, and as adults, aged 20 to 37 years, with an average follow-up period of 16 years. Microalbuminuria is defined as urinary albumin (in milligrams per liter) to creatinine (mmoles per liter) ratio at or above the 90th percentile specific for age, ethnicity, and sex or urinary albumin levels >/=30 mg/L. RESULTS: As children, African American boys had higher BP than white boys. As adults, African Americans had higher BP and urinary albumin/creatinine ratio than whites. After adjusting for age, sex, and body mass index (BMI), African Americans with microalbuminuria in adulthood by either measure had higher systolic (P =.03) and diastolic (P =.02) BP as adults, and higher diastolic (P <.01) as children than those without this condition. On the other hand, whites showed no such significant association. In a multivariate regression analysis, adjusting for sex, childhood BMI, and age, and current smoking status, childhood BP and rate of change in BP from childhood to adulthood were significant predictors of increased urine albumin excretion in African Americans, but not in whites. CONCLUSIONS: Elevated BP beginning in childhood is associated with microalbuminuria in adulthood in African Americans, but not in whites, suggesting that African Americans may be more susceptible than whites to BP-related renal damage.