Whole-mount Immunohistochemistry to Visualize Mouse Embryonic Dermal Lymphatic Vasculature

Lymphatic vessels are abundant in the skin where they regulate interstitial fluid uptake and immune surveillance. Defects in dermal lymphatic vessels, such as fewer vessels and abnormal lymphatic vessel coverage with mural cells, are frequently associated with lymphedema and other lymphatic disorders. Whole-mount immunohistochemistry allows the visualization of dermal lymphatic vessels and identifies morphogenetic defects. Most dermal lymphatic vessels start growing during embryogenesis from lymph sacs that are located close to the axilla towards the dorsal and ventral midlines. Here, we present an approach that we have developed to permeabilize, immunolabel, clear, and visualize the lymphatic vessels. These simple and inexpensive techniques reproducibly generate images of dermal lymphatic vessels with great clarity.

Mothers' sense of coherence and oral health related quality of life of preschool children in Udupi Taluk

OBJECTIVE

To assess the relationship between mothers' Sense of Coherence (SOC) and oral health related quality of life (OHRQoL) of 3-5 year old preschool children in Udupi Taluk.

PARTICIPANTS

388 mothers aged 24-48 years old and their preschool children.

BASIC RESEARCH DESIGN

A cross sectional study of mother-child pairs, randomly selected from 8 preschools.

METHOD

Information was obtained about mothers' sociodemographic factors along with the short version (SOC 13) of Antonovsky's sense of coherence scale and children's OHRQoL using the early childhood oral health impact scale (ECOHIS). Chi-square tests and multivariate logistic regression were used for analysis.

MAIN OUTCOME MEASURES

Mothers' SOC and children's OHRQoL.

RESULTS

Mothers' SOC and fathers' education were significantly associated with children's OHRQoL in multivariate analysis. Children of mothers with high SOC were 12.9 times as likely to have high OHRQoL as mothers with low SOC (p < 0.01). Children of fathers with college/university education were twice as likely to have high OHRQoL as those with primary education (p < 0.05).

CONCLUSION

Our results suggest that mother's SOC could be a psychosocial determinant of the OHRQoL of their preschool children. Family environment should be considered when designing interventions to promote or improve the oral health as well as OHRQoL of preschool children.

Common genetic variation near the connexin-43 gene is associated with resting heart rate in African Americans: a genome-wide association study of 13,372 participants

BACKGROUND

Genome-wide association studies have identified several genetic loci associated with variation in resting heart rate in European and Asian populations. No study has evaluated genetic variants associated with heart rate in African Americans.

OBJECTIVE

To identify novel genetic variants associated with resting heart rate in African Americans.

METHODS

Ten cohort studies participating in the Candidate-gene Association Resource and Continental Origins and Genetic Epidemiology Network consortia performed genome-wide genotyping of single nucleotide polymorphisms (SNPs) and imputed 2,954,965 SNPs using HapMap YRI and CEU panels in 13,372 participants of African ancestry. Each study measured the RR interval (ms) from 10-second resting 12-lead electrocardiograms and estimated RR-SNP associations using covariate-adjusted linear regression. Random-effects meta-analysis was used to combine cohort-specific measures of association and identify genome-wide significant loci (P≤2.5×10(-8)).

RESULTS

Fourteen SNPs on chromosome 6q22 exceeded the genome-wide significance threshold. The most significant association was for rs9320841 (+13 ms per minor allele; P = 4.98×10(-15)). This SNP was approximately 350 kb downstream of GJA1, a locus previously identified as harboring SNPs associated with heart rate in Europeans. Adjustment for rs9320841 also attenuated the association between the remaining 13 SNPs in this region and heart rate. In addition, SNPs in MYH6, which have been identified in European genome-wide association study, were associated with similar changes in the resting heart rate as this population of African Americans.

CONCLUSIONS

An intergenic region downstream of GJA1 (the gene encoding connexin 43, the major protein of the human myocardial gap junction) and an intragenic region within MYH6 are associated with variation in resting heart rate in African Americans as well as in populations of European and Asian origin.

Longitudinal versus cross-sectional evaluations of leukocyte telomere length dynamics: age-dependent telomere shortening is the rule

BACKGROUND

Leukocyte telomere length (LTL) is considered a biomarker of human aging and based on cross-sectional studies it shortens with age. However, longitudinal studies reported that many adults display LTL lengthening.

METHODS

Using Southern blots, we compared cross-sectional rates of age-related LTL change across a ∼20 year age range with those based on longitudinal evaluations in three surveys (S1, S2, and S3) with three time intervals: S1-S2 (5.8 years), S2-S3 (6.6 years), and S1-S3 (12.4 years). Hierarchical linear modeling was used to explore LTL dynamics using LTL data from S1, S2, and S3.

RESULTS

Cross-sectionally, mean LTL shortenings were 24.6, 25.4, and 23.6 bp/y at S1, S2, and S3, respectively. Longitudinally, more variation was observed in the rate of LTL change during the shorter than longer follow-up periods. Furthermore, using simple differences in LTL, 14.4% and 10.7% of individuals displayed LTL lengthening during S1-S2 and S2-S3, respectively, but only 1.5% during S1-S3 (p < 0.001). The estimated mean rate of LTL shortening based on averaging empirical Bayes' estimates of LTL from a parsimonious hierarchical linear modeling model was 31 bp/y with a range from 23 to 47 bp/y with none of the participants showing LTL lengthening over the average 12.4 years of follow-up.

CONCLUSIONS

As aging displays a unidirectional progression, it is unlikely that LTL elongates with age. LTL elongation in longitudinal studies primarily reflects measurement errors of LTL in relation to the duration of follow-up periods.

Influence of lipoprotein lipase gene Ser447Stop and β1-adrenergic receptor gene Arg389Gly polymorphisms and their interaction on obesity from childhood to adulthood: the Bogalusa Heart Study

OBJECTIVE

To investigate the influence of lipoprotein lipase (LPL) Ser447Stop and beta1-adrenergic receptor (ADRB1) Arg389Gly gene polymorphisms, individually and in combination, on obesity from childhood to adulthood.

DESIGN AND SUBJECTS

A community-based cohort of 1331 subjects (30% black and 70% white subjects) was followed over an average period of 23 years from childhood (age range: 4-17 years) to adulthood (age range:18-44 years).

MEASUREMENT

Body mass index (BMI, kg/m2) and LPL Ser447Stop and the ADRB1 Arg389Gly genotypes.

RESULTS

The frequency of the ADRB1 Gly389 allele was 0.25 in white subjects vs 0.39 in black subjects (P < 0.001); 0.08 vs 0.05 (P = 0.280) for the LPL Stop447 allele. There was no association between the LPL Stop447 allele and BMI among white and black subjects either in childhood and adulthood levels or annual change from childhood to adulthood. The ADRB1 Gly389 allele was associated with lower BMI only in black adults (P = 0.017). Further, the interaction effect of the LPL Stop447 allele and ADRB1 Gly389 allele on adult BMI or its annual change was significant in white subjects and in the total sample (P = 0.03-0.006). Childhood values tended to show a similar trend. Having both ADRB1 Gly389 allele and LPL Stop447 allele was associated with 71% (95% confidence interval: 26-89%) less odds for developing obesity from childhood to adulthood after adjusting for age, race, sex, and childhood BMI.

CONCLUSION

While Gly389 allele of the ADRB1 gene lowers obesity in black subjects, this allele in conjunction with Stop447 allele of the LPL gene lowers obesity in adults and attenuates the development of obesity from childhood to adulthood. These findings underscore the importance of gene-gene interaction in the assessment of genetic influences on complex traits such as obesity.

Correlates of carotid artery stiffness in young adults: The Bogalusa Heart Study

Decreased arterial elasticity, an independent risk factor for cardiovascular (C-V) disease, is associated with C-V risk factors in middle-aged and older individuals. However, information is limited in this regard in young adults. This aspect was examined in a community-based sample of 516 black and white subjects aged 25-38 years (71% white, 39% male). The common carotid artery elasticity was measured from M-mode ultrasonography as Peterson's elastic modulus (Ep) and relative wall thickness-adjusted Young's elastic modulus (YEM). Blacks and males had higher Ep (P < 0.05); males had higher YEM (P < 0.0001); and blacks had higher wall thickness (P < 0.01). For the entire sample adjusted for race and gender both Ep and YEM correlated significantly (P < 0.05-0.0001) with age, BMI, waist, systolic and diastolic blood pressures, heart rate, product of heart rate and pulse pressure, triglycerides, total cholesterol to HDL cholesterol ratio, insulin and glucose. In a multivariate regression model that included hemodynamic variables, systolic blood pressure, product of heart rate and pulse pressure, age, triglycerides, BMI, and male gender (for YEM only) were independent correlates of Ep (R2 = 0.38) and YEM (R2 = 0.25). When the hemodynamic variables were excluded from the model, age, triglycerides, BMI, black race (Ep only), male gender, parental history of hypertension, HDL cholesterol (inverse association), and insulin (marginal significance) remained independent correlates of Ep (R2 = 0.20) and YEM (R2 = 16). Both Ep and YEM increased (P for trend P < 0.0001) with increasing number of independent continuous risk factors (defined as values above or below the age, race, and gender-specific extreme quintiles) that were retained in the regression models. The observed increasing arterial stiffness (or decreased elasticity) with increasing number of risk factors related to insulin resistance syndrome in free-living, asymptomatic young adults has important implications for prevention.

An autosomal genome scan for loci influencing longitudinal burden of body mass index from childhood to young adulthood in white sibships: The Bogalusa Heart Study

OBJECTIVE

To examine genetic loci linked to a long-term burden and trend of obesity traits, such as body mass index (BMI), from childhood to adulthood.

DESIGN

: Longitudinal study using serial measurements of BMI from childhood.

SUBJECTS

A total of 782 unselected white siblings (representing 521 full and 39 half sib-pairs) from 342 families enrolled in the Bogalusa Heart Study.

MEASUREMENTS

A total of 357 microsatellite markers with an average spacing of 9.0 cM spanning the 22 autosomal chromosomes were typed. A quadratic growth curve was developed using a random effects model based on serial measurements of BMI from childhood to adulthood. The serial changes in BMI were measured in terms of long-term burden (area under the curve (AUC) divided by follow-up years) and the long-term trend (incremental AUC, calculated as total AUC-baseline AUC).

RESULTS

Heritability estimates of long-term measures were 0.78 for total AUC and 0.43 for incremental AUC. In a variance-component-based multipoint linkage analysis with SOLAR, linkage to the long-term measures of BMI was observed on chromosomes 1, 5, 7, 12, 13 and 18. For total AUC, LOD scores were 3.0 at 110 cM on chromosome 12, 2.9 at 26 cM and 2.4 at 52 cM on chromosome 7, and 2.2 at 126 cM on chromosome 5. For incremental AUC, LOD scores were 2.9 at 26 cM, 2.1 at 97 cM and 2.3 at 110 cM on chromosome 12, 2.2 at 69 cM on chromosome 7, 2.2 at 91 cM and 2.5 at 150 cM on chromosome 1, 2.0 at 119 cM on chromosome 5, 2.0 at 54 cM on chromosome 13 and 2.0 at 7 cM on chromosome 18. Several important obesity-related candidate genes are located in the regions or near the markers showing positive linkage.

CONCLUSION

Linkage evidence found in this study indicates that regions on these chromosomes might harbor genetic loci that affect the propensity to develop obesity from childhood.

Longitudinal changes in risk variables underlying metabolic Syndrome X from childhood to young adulthood in female subjects with a history of early menarche: the Bogalusa Heart Study

OBJECTIVES

To examine the longitudinal changes in adiposity and related risk variables of Syndrome X from childhood to young adulthood with respect to early onset of menarche.

DESIGN

Community-based longitudinal cohort of female subject (65% white, 35% blacks subjects) who participated in two or more surveys from childhood to young adulthood and had reported their menarcheal age (<12 y, n=437 vs > or =12 y, n=1042).

RESULTS

In childhood (5-11 y), adolescence (12-18 y), and young adulthood (19-37 y), females with early menarche displayed significantly higher body mass index (BMI) and triceps skinfold thickness; higher stature in childhood and adolescence; higher fasting insulin and homeostasis model assessment index of insulin resistance (HOMA-IR) in childhood and adulthood; and higher fasting glucose in adulthood. Blood pressure and lipoprotein variables showed no early menarche-related differences. Longitudinal rates of change in BMI (P=0.002), triceps skinfold thickness (P=0.05), insulin (P=0.09), and HOMA-IR (P=0.05) were positive and faster among female subjects with early menarche; fasting glucose decreased slowly in this group (P=0.006). In a multivariate analysis, body fatness and insulin related independently to early menarche (P<0.001). This association was stronger in white subjects (P=0.0008). In adulthood, the prevalence of clustering of three to four risk factors of syndrome X (highest quartile of: (1) BMI, (2) fasting insulin, (3) systolic or mean arterial pressure, and (4) total cholesterol to HDL cholesterol or triglycerides to HDL cholesterol ratio specific for age, race, and study year) was higher among those with early menarche (10.7 vs 6.2%, P=0.002). The odds for developing such clustering in adulthood among those with early menarche was 1.54 (95% CI=1.14-2.07), regardless of race.

CONCLUSION

Early menarche is characterized by excess body fatness and insulin beginning in early childhood and higher prevalence of clustering of adverse levels of risk variables of metabolic Syndrome X in young adulthood.

Inter-relationships among childhood BMI, childhood height, and adult obesity: the Bogalusa Heart Study

OBJECTIVE

Although the body mass index (BMI, mass index, kg/m2) is widely used as a surrogate measure of adiposity, it is moderately associated (r approximately 0.3) with height among children. We examined whether the resulting preferential classification of taller children as overweight is appropriate.

DESIGN

Cross-sectional analyses of children (ages, 3-17 y) examined the relation of height to adiposity (as assessed by BMI and skinfold thicknesses) and fasting levels of insulin. Longitudinal analyses examined the relation of childhood height and weight-height indices to adult (mean age, 25 y) levels of adiposity and fasting insulin.

SUBJECTS

Children (n=11,406) and adults (n=2911) who had participated in the Bogalusa Heart Study.

MEASUREMENTS

We constructed three weight-height indices: BMI, W/H3, and W/Hp. The triceps and subscapular skinfolds, as well as fasting levels of insulin, were also measured.

RESULTS

The classification of children as overweight (BMI-for-age > or =95th percentile) varied markedly by height, with a 10-fold difference in the prevalence of overweight across quintiles of height between the ages of 3 and 10 y. Childhood height, however, was also related to skinfold thicknesses and insulin levels, and all associations were modified in a similar manner by age. Furthermore, childhood height was related to adult adiposity, and of the three childhood weight-height indices, BMI showed the strongest associations with adult adiposity.

CONCLUSIONS

Because BMI reflects the positive association between height and adiposity among children, it is a better weight-height index than is either W/H3 or W/Hp.

Differences in body shape representations among young adults from a biracial (Black-White), semirural community: the Bogalusa Heart Study

In this study, the authors examined body image perception and body mass index (weight (kg)/height (m)(2)) among race-gender groups in a biracial (Black-White) population of young adults in Bogalusa, Louisiana. A mail-out survey was completed in 1994 by 3,698 (65%) participants aged 18.5-35 years in the Bogalusa Heart Study (mean age = 27.6 years). As part of the survey, body image perception was determined in terms of body shape representations from a figure rating scale. A body image discrepancy score was calculated from the difference between z-standardized values of body image perception and body mass index. A stepwise proportional odds model including the covariates income, employment, education, and physical activity was used to identify factors influencing lower perception of body shape. Mean body mass index was highest among Black females (p < 0.001). The odds of having a lower perception of body shape (vs. body mass index) were 1.72 times higher in Blacks (p < 0.001), 0.80 times lower in persons who were currently employed (p < 0.001), and 0.86 times lower in persons with a higher education (p = 0.032). Gender, income, and physical activity were not found to be significant predictors of body image perception (p > 0.05). The authors conclude that significant differences exist within racial groups concerning body image perception in relation to overweight status among young adults. This has implications for prevention and education programs.

Influence of the beta2-adrenergic receptor Arg16Gly polymorphism on longitudinal changes in obesity from childhood through young adulthood in a biracial cohort: the Bogalusa Heart Study

BACKGROUND

The beta2-adrenergic receptor (ADRB2) plays a major role in regulating energy expenditure by stimulating lipid metabolism in human adipose tissue. Polymorphisms in the ADRB2 gene have been associated with obesity and various weight-related traits in cross-sectional studies of adults, but little is known about the effects of the ADRB2 gene on childhood obesity or the propensity to gain weight over time.

OBJECTIVE

To assess the effects of a polymorphism in codon 16 (Arg16-->Gly) of the ADRB2 gene, which has been associated with a decrease in beta2-receptor density and efficiency, on longitudinal changes in obesity from childhood to young adulthood in a biracial cohort.

DESIGN

Seven cross-sectional screenings of children and five cross-sectional screenings of young adults who were previously examined as children produced longitudinal data from childhood to young adulthood.

METHODS

Height, weight and subscapular and triceps skinfolds were measured by trained examiners following identical protocols over the course of the study. Gender- and age-stratified analyses using random coefficients models were used to examine longitudinal genetic effects on obesity in 1151 African-American and Caucasian males and females who attended an average of six examinations over a 24 y period from childhood to young adulthood.

RESULTS

Age-stratified analyses showed no clear genetic relationships with changes in obesity measures over time in females, but an age-dependent association was observed in males, where the relationship between the Arg16Gly polymorphism and obesity became stronger with age. In males who were 4-9 y of age at the beginning of the study in 1973, body mass index (BMI) was 4% higher in Gly/Gly and Arg/Gly males compared to those with Arg/Arg by 26 y of age. Subscapular skinfold measurements in Gly/Gly males became significantly different from Arg/Arg males (20% higher) by age 20. In the oldest male cohort (10-14 y of age in 1973), BMI increased at a significantly greater rate (0.4%/y) in males carrying the Gly16 form of the receptor relative to Arg/Arg males. BMI was significantly different between homozygous genotypes by approximately 26 y of age, and reached 8% higher in Gly/Gly males by age 32. Subscapular skinfolds also increased at a significantly greater rate (2%/y) in Gly/Gly males compared to Arg/Arg males, becoming significantly different (27%) by approximately 22 y of age and reaching a maximum difference of 50% by age 32.

CONCLUSIONS

Our data suggest that the beta2-adrenergic receptor is associated with the propensity to gain weight from childhood to young adulthood in males. An increased understanding of genetic influences on the development of obesity may improve the effectiveness of interventions designed to reduce excess body weight and help define the role of genetic factors in diabetes and cardiovascular disease.

Emergence of obesity and cardiovascular risk for coronary artery disease: the Bogalusa Heart Study

The underlying determinants of cardiovascular risk are governed by both genetic and lifestyle factors. One of the major adverse outcomes of unhealthy lifestyles is obesity, the genesis of which begins in childhood. Obesity, an important risk factor for atherosclerotic cardiovascular disease, type 2 diabetes, and hypertension, persists (tracks) strongly from adolescent years to adulthood. Secular trends toward increased obesity in the past 25 years have occurred in children and adults alike. Of interest, baseline adiposity precedes hyperinsulinemia in all age groups, independently of race, sex, and baseline insulin levels. Adiposity is an independent predictor of the risk of developing the cluster of risk variables of the metabolic syndrome X, beginning in childhood. Exposure to a multiple risk factor burden over time enhances the development of coronary atherosclerosis and hypertensive cardiovascular disease. In fact, autopsy studies in youths have shown that the extent of fibrotic atherosclerotic plaques in coronary arteries, measured antemortem, increases markedly with the presence of syndrome X risk variables. Further, in overweight children, insulin levels are associated with left ventricular mass. In young people, overnutrition, coupled with physical inactivity, leads to weight gain. Since obesity, unhealthy dietary habits, and a sedentary lifestyle are interrelated and modifiable, prevention and intervention must begin in early life. (c)2001 CHF, Inc.

Trends of lipoprotein variables from childhood to adulthood in offspring of parents with coronary heart disease: the Bogalusa Heart Study

Although dyslipidemia among offspring of parents with coronary heart disease (CHD) has been known, the development of this adverse relationship with respect to specific lipoprotein variables from childhood to young adulthood has not been elucidated. This aspect was examined in a young adult cohort with (n = 271) and without (n = 805) a parental history of CHD followed longitudinally since childhood by repeated surveys from 1973 to 1991. Trends in fasting lipoprotein variables by parental CHD status were assessed by Lowess smoothing curve and Generalized Estimating Equations (GEE). In multivariate analyses adjusted for race and sex, parental CHD associated positively with low-density lipoprotein cholesterol (LDL-C, P <.01) and triglycerides (P <.05) mainly at the young adulthood age, whereas a positive association was noted with very-low-density lipoprotein cholesterol (VLDL-C) during both childhood and young adulthood (P <.05). The positive association between parental CHD and LDL-C in young adulthood persisted independently of body mass index (BMI) and fasting insulin, but disappeared when fasting glucose was added to the model. With respect to triglycerides and VLDL-C, inclusion of BMI, insulin, and/or glucose eliminated the adverse association with parental CHD. These observations suggest that parental CHD is just one more explanatory variable that loses its partial contribution to lipoprotein profiles in their offspring when other strongly interrelated contributory variables such as age, body fatness, and measures of glucose homeostasis are taken into account. Information on these risk variables in conjunction with parental or family history of CHD may enhance the potential of CHD risk assessment in youth.

Distribution and correlates of lipoproteins and their subclasses in black and white young adults. The Bogalusa Heart Study

Lipoprotein subclasses vary in CAD risk potential, but their distribution and correlates are not well documented in black and white young adults. A subsample of 449 (32%) young adults (67% white, 58% female) aged 20-37 years examined in the Bogalusa Heart Study had lipoprotein subclasses measured in terms of cholesterol by vertical spin density-gradient ultracentrifugation. LDL subclass pattern was characterized as either predominantly LDL(1) (large, buoyant), LDL(2) (intermediate) or LDL(3) (small, dense). Whites had significantly higher levels of VLDL, VLDL(3), and LDL and lower levels of HDL(2) and HDL(3) than blacks. White females had significantly higher levels of HDL(2) than white males. Visceral fatness, measured as waist circumference, and race were the major contributors to the explained variance (6-22%) of these lipoproteins, with adverse trends seen among whites and persons with large waist circumferences. Sex (males>females), waist circumference (positive), HDL(2) (negative), and HDL(3) (positive) were the predictor variables for the likelihood of having the LDL(3) pattern. When glucose and insulin were included in the multivariate analysis, insulin (positive), sex (males>females), HDL(2) (negative) and HDL(3) (positive) became significant predictors of LDL(3) pattern. Positive parental history of CAD was associated with LDL (P=0.009) in white males, and HDL(2) (P=0.008) and LDL(3) subclass pattern (P=0.038) in white females; whereas none in blacks. The observed correlates of lipoprotein subclasses and patterns need to be considered in estimating CAD risk in young adults.

Influence of lipoprotein lipase serine 447 stop polymorphism on tracking of triglycerides and HDL cholesterol from childhood to adulthood and familial risk of coronary artery disease: the Bogalusa heart study

The effects of the lipoprotein lipase (LPL) Serine 447 Stop (S447X) polymorphism on high-density lipoprotein cholesterol (HDLC) and triglycerides (TG) have been demonstrated. However, little is known about its effect on the tracking of HDLC and TG over time and familial risk of coronary artery disease (CAD). This aspect was examined in black and white individuals (n=829) aged 5-18 year at baseline, followed on average 18.8 yr. The frequency of the X447 allele was lower in Blacks than Whites (0.043 vs. 0.087, P=0.002). Carriers vs. noncarriers of the X447 allele had lower TG (99.3 vs 122.1 mg/dl, P<0.01) and higher HDLC (51.1 vs. 49.7 mg/dl, P<0.05) in adulthood, but not in childhood. The trends in genotype-specific means of childhood and adulthood levels of HDLC and TG in sex or race subgroups were similar to those in the total sample. With respect to tracking over time, of those in the bottom quartile of HDLC in childhood, 46.1% of the noncarriers vs. 23.1% of the carriers remained in this lowest quartile into adulthood (P=0.03); corresponding values for the top quartile of HDLC were 37.5% for the noncarriers vs. 57.1% for the carriers (P=0.03). Although TG tended to track better among the carriers in the bottom quartile and among the noncarriers in the top quartile, this trend was not significant. Carriers showed lower prevalence of parental history of CAD than noncarriers (6.9% vs. 14.1%, P=0.02) independently of lipoprotein variables, adiposity, blood pressure, age, sex and race. Thus, the X447 allele of the LPL gene is associated with an increase in HDLC and a decrease in TG in adults, tracking of HDLC since childhood, and a lower family history of CAD.

The magnitude of familial associations of cardiovascular risk factor variables between parents and offspring are influenced by age: the Bogalusa Heart Study

PURPOSE

Although parent-offspring associations of cardiovascular risk factor variables are known, the age-specific nature of this familial relationship is not clear.

METHODS

This aspect was examined in 727 unrelated children (mean age: 11.2 years) and their parents who participated in the Bogalusa Heart Study during their childhood (mean age: 11.3 years) and adulthood (mean age: 25.5 years).

RESULTS

After adjusting for covariates, the mothers' childhood-offspring correlations were consistently higher than mothers' adulthood-offspring correlations for body mass index (BMI) [r = 0.45 vs. 0.32], systolic blood pressure (SBP) [r = 0.30 vs. 0.10], diastolic blood pressure (DPB) [r = 0.22 vs. 0.13] and low-density lipoprotein cholesterol (LDLC) [r = 0.20 vs. 0.11]. In contrast, high-density lipoprotein cholesterol (HDLC) and triglycerides did not show such age-specific trends in mother-offspring correlations. Corresponding father-offspring correlations showed similar patterns, but the differences were of lesser magnitude. Multiple regression analyses using offspring's risk factor variables as dependent variables revealed that parents' childhood obesity, blood pressure and LDLC levels were better predictors of the corresponding variables in the young offspring than parents' adulthood values. Further, sex of either parents or offspring made no difference in the above findings.

CONCLUSIONS

The magnitude of the familial associations of cardiovascular risk factor variables between parents and offspring are influenced by age. Intrinsic genetic make-up, duration of exposure to environment and gene-environment interactions may play a role in this association.

Combined effects of endothelial nitric oxide synthase gene polymorphism (G894T) and insulin resistance status on blood pressure and familial risk of hypertension in young adults: the Bogalusa Heart Study

Impaired endothelial function with decreased nitric oxide production is shared by insulin resistance and essential hypertension. Although there are limited data on the association between the endothelial nitric oxide synthase (eNOS) G894T polymorphism and hypertension, information is absent on the combined effects of eNOS G894T genotype and insulin resistance status on blood pressure (BP) levels and the familial risk of hypertension. This aspect was examined in a community-based sample of 1021 unrelated African American and white young adults aged 19 to 38 years. African Americans displayed a lower frequency of the T894 allele than whites (0.105 v 0.324, P < .001). After adjusting for sex, age, and body mass index (BMI), noncarriers versus carriers of the T894 allele had significantly higher systolic (SBP), diastolic (DBP) BP and mean arterial pressure (MAP) levels (111.7 v 109.2 mm Hg for SBP; 73.6 v 72.3 mm Hg for DBP; 86.3 v 84.6 mm Hg for MAP), with both African Americans and whites showing similar trends. This association was modulated by insulin resistance status, measured by the homeostasis model assessment of insulin resistance (HOMA IR) using fasting insulin and glucose. Subjects with high insulin resistance (above the median HOMA IR) showed significantly greater differences in BP levels between noncarriers and carriers of the T894 allele. Furthermore, the G894T genotype and insulin resistance also showed a combined effect on the prevalence of parental hypertension, a measure of familial risk, with noncarriers versus carriers in the high insulin resistance group showing higher prevalence (70.5% v 51.3%, P = .006, adjusted for race). Thus, the allelic variation (G894T) in the eNOS gene locus in conjunction with insulin resistance may be one factor contributing to the predisposition to hypertension.

Consideration of serum cholesterol in risk factor profiling for all young individuals

AIM

To alter the adverse natural course of coronary artery disease and its risk factors, primary prevention should begin in childhood.

DATA SYNTHESIS

High serum cholesterol, LDL cholesterol (LDL-C) in particular, remains the major determinant of atherosclerotic process beginning in childhood. Selective cholesterol screening of children based on family history is inadequate. Tracking of childhood elevated cholesterol in conjunction with other risk factors into adulthood argues in favor of universal screening in the young. Further, individual adverse levels of LDL-C not only increase the incidence of adulthood dyslipidemia, but also markedly enhances the prevalence of obesity and hypertension seen in the adult population.

CONCLUSIONS

Screening of all young individuals for serum cholesterol along with a cardiovascular risk factor profile is recommended. Cardiovascular disease remains a public health issue and identifying young individuals at risk is basic to prevention.

Relationship of childhood obesity to coronary heart disease risk factors in adulthood: the Bogalusa Heart Study

BACKGROUND

Childhood obesity is related to adult levels of lipids, lipoproteins, blood pressure, and insulin and to morbidity from coronary heart disease (CHD). However, the importance of the age at which obesity develops in these associations remains uncertain.

OBJECTIVE AND DESIGN

We assessed the longitudinal relationship of childhood body mass index (BMI, kg/m(2)) to adult levels of lipids, insulin, and blood pressure among 2617 participants. All participants were initially examined at ages 2 to 17 years and were reexamined at ages 18 to 37 years; the mean follow-up was 17 years.

RESULTS

Of the overweight children (BMI >/=95th percentile), 77% remained obese (>/=30 kg/m(2)) as adults. Childhood overweight was related to adverse risk factor levels among adults, but associations were weak (r ~ 0.1-0.3) and were attributable to the strong persistence of weight status between childhood and adulthood. Although obese adults had adverse levels of lipids, insulin, and blood pressure, levels of these risk factors did not vary with childhood weight status or with the age (</=8 years, 12-17 years, or >/=18 years) of obesity onset.

CONCLUSIONS

Additional data are needed to assess the independent relationship of childhood weight status to CHD morbidity. Because normal-weight children who become obese adults have adverse risk factor levels and probably will be at increased risk for adult morbidity, our results emphasize the need for both primary and secondary prevention.

Comparison of weight-for-height indices as a measure of adiposity and cardiovascular risk from childhood to young adulthood: the Bogalusa heart study

The development of obesity in childhood is considered a major determinant of cardiovascular risk. Currently the body mass index (BMI = weight/height(2)) is widely used as a measure of obesity. However, since BMI is associated with height during childhood, a weight for height index (weight/height(p)) that is independent of height is thought to be more appropriate. Therefore, to compare the utility of such weight/height(p) index with BMI in assessing adiposity and its relation to cardiovascular risk variable data from the Bogalusa Heart Study participants aged 6 months to 21 years were examined. A total of 31,796 observations on 12,827 subjects was used in the data analysis. Study variables include height, weight, subscapular and triceps skinfolds, blood pressure, serum lipids and lipoproteins, and plasma glucose and insulin. The optimal exponential for the weight/height(p) index started from 2.42 in the 6 month olds, decreased to 1.86 in 2 to 3 year olds, increased to 3.29 among 10 to 11 year olds, and then decreased to 2.15 in the 20 to 21 year olds. The BMI showed slightly higher correlations than weight/height(p) index with subscapular skinfold in children. Both in children and young adults BMI also showed a slightly higher correlation with other cardiovascular risk factor variables regardless of age-race-sex groups. These results indicate that weight/height(p) index is not superior to BMI as an indicator of adiposity and related cardiovascular risk factors during childhood.

The Ser(447)-Stop polymorphism of lipoprotein lipase is associated with variation in longitudinal serum high-density lipoprotein-cholesterol profiles: the Bogalusa Heart Study

The Ser(447)-Stop polymorphism of lipoprotein lipase (LPL) has been associated with altered high-density lipoprotein-cholesterol (HDL-C) and triglyceride (TG) levels at individual measurements, but nothing is known of its associations with lipid profiles derived from serial measurements. We used multilevel statistical models to study effects of this polymorphism on longitudinal lipid profiles in 1,006 Bogalusa Heart Study subjects examined 4 to 9 times between the ages of 4 and 38 years. Stop(447) allele frequencies in African Americans (0.053 +/- 0.011) and whites (0.091 +/- 0.009) differed significantly (chi(2) = 7.595, 1 df, P =.006; Stop(447) homozygotes and heterozygotes combined). Overall, TG levels were lower and HDL-C levels higher in blacks than in whites of the same age and sex. Longitudinal TG profiles were lower in Stop(447) carriers at all ages. However, longitudinal HDL-C profiles differed among genotype groups with age: the Stop(447) allele was associated with higher HDL-C only in subjects above approximately 10 years of age. Genotype-specific HDL-C profiles also differed significantly among race/sex groups. Thus, we found evidence of LPL genotype effects that vary within individuals with age. Possible mechanisms, which could account for age-related changes in the effects of LPL variants, are discussed.

Apolipoprotein E polymorphism modulates the association between obesity and dyslipidemias during young adulthood: The Bogalusa Heart Study

To elucidate to what extent apolipoprotein (apo) E polymorphism modulates obesity-induced dyslipidemias during young adulthood, longitudinal data on 759 individuals (72% white/28% black; initial and follow-up mean age, 25.9 and 32.7 years) were examined. Among both races and the total sample, the apo E2 group (with E2/2 or E2/3 phenotype) had significantly lower and the apo E4 (with E4/4 or E3/4 phenotype) group higher low-density lipoprotein (LDL) cholesterol than the apo E3 (with E3/3 phenotype) group at both examinations. In addition, the apo E2 group displayed higher high-density lipoprotein (HDL) cholesterol in the total sample. No allele-specific effect was noted for the longitudinal changes (Delta). An increase in Delta adiposity, measured as Delta body mass index (BMI), was accompanied by higher increase in Delta LDL cholesterol in the e4 carriers than the e2 carriers among the whites (P <.05) and the total sample (P <.01); an increase in Delta triglycerides and decrease in Delta HDL cholesterol in the e2 carriers than the e4 carriers among all the groups (P <.05 to.001). Among the apo E phenotype groups, the incidence of high (>75th percentile specific for race and sex) LDL cholesterol at follow-up was in the order E4 > E3 > E2 both in the obese (BMI > 30; P for trend =.033) and the nonobese (BMI < 25; P for trend =.035) groups. Although the increase of low (<25th percentile specific for race and sex) HDL cholesterol or high triglycerides showed no apo E phenotype-specific trend, the incidence of high triglycerides without high LDL cholesterol was in the order E2 > E3 > E4 only in the obese group (P for trend =.025). The prevalence trend for dyslipidemias at follow-up among the persistently obese and nonobese groups also gave similar results. Thus, apo E gene locus influences not only the levels of certain lipoprotein variables during young adulthood, but also modulates the association between obesity and dyslipidemias.

Trends in nutrient intake of 10-year-old children over two decades (1973-1994) : the Bogalusa Heart Study

Dietary intakes of 10-year-old children were examined in seven cross-sectional surveys to observe secular trends in nutrient intake and food consumption patterns over 2 decades (1973-1994). Total energy intake remained unchanged from 1973 to 1994. However, when expressed as energy per kilogram body weight, intake decreased from 65.5 kcal in 1973 to 55.4 kcal in 1994 because children's weight increased. A significant trend was noted in ponderal index, which increased from 12.31 (1973-1974) to 13.71 (1992-1994), with an actual weight gain of 1.45 kg from 1973 to 1979 and 2.71 kg from 1981 to 1994. Linear trends also were noted for total fat (negative), saturated fat (negative), dietary cholesterol (negative), polyunsaturated fat (positive), and total carbohydrate (positive). There was a significant increase in percent energy from protein and carbohydrate and a significant decrease in percent energy from fat, primarily saturated and monounsaturated fat. Trends in nutrient intakes of children reflected trends in food consumption. The percentage of total fat from fats/oils, mixed meats, eggs, milk, pork, and desserts decreased, while that from poultry, cheese, and snacks increased. Although more children met dietary recommendations for total fat, saturated fat, and dietary cholesterol, the vast majority continued to exceed prudent diet recommendations.

BMI rebound, childhood height and obesity among adults: the Bogalusa Heart Study

OBJECTIVE

The beginning of the post-infancy rise in the body mass index (BMI, kg/m2) has been termed the adiposity rebound, and several studies have found that an early rebound increases the risk for overweight in adulthood. We examined whether this relation is independent of childhood BMI levels.

DESIGN

A longitudinal study of 105 subjects who examined at ages 5, 6, 7, 8 and 19-23 y.

RESULTS

Subjects with an age at the BMI rebound (age(min)) of < or =5 y were, on average, 4-5 kg/m2 heavier in early adulthood than were subjects whose age(min) was > or =7 y. Age(min), however, was also correlated with childhood BMI levels (r approximately -0.5), and we found that age(min) provided no additional information on adult overweight if the BMI level at age 7 y (or 8 y) was known. In contrast, childhood height, which was also correlated with age(min) (r=-0.47), was independently related to adult BMI. Among relatively heavy (BMI=16.0 kg/m2) 5-y-olds, a child with a height of 120 cm was estimated to be 1.2 kg/m2 heavier in adulthood than would a 104 cm tall child.

CONCLUSIONS

Although an early BMI rebound was related to higher levels of relative weight in adulthood, this association was not independent of childhood BMI levels. The relation of childhood height to adult BMI needs to confirmed in other cohorts, but it is possible that childhood height may help identify children who are likely to become overweight adults.

Distribution and cardiovascular risk correlates of serum triglycerides in young adults from a biracial community: the Bogalusa Heart Study

Elevated serum triglyceride level is increasingly being recognized as an important indicator of cardiovascular risk. The distribution and correlates of serum triglycerides were examined in a biracial (black-white) community-based sample of 1342 young adults (30% black) aged 20-37 years. Triglyceride levels showed significant race (white>black) and sex (male>female) differences. Black females, despite their relatively increased body fatness, had lowest triglyceride levels. In terms of conjoint trait of dyslipidemia based on the National Cholesterol Education Program cutpoints, 9% of white males displayed high triglyceride (> or =200 mg/dl) in combination with low high-density lipoprotein (HDL)-cholesterol (<35 mg/dl). In comparison, none of the black females fell into this category. Serum triglycerides even at levels between 100 and 150 mg/dl were significantly adversely associated with risk variables of insulin resistance syndrome such as adiposity and visceral fatness measures, HDL-cholesterol, insulin, and systolic blood pressure, especially among whites. Visceral fatness as measured by waist circumference (except black males) and insulin were the major predictors of triglyceride levels. Overall, triglyceride levels above 150 mg/dl were associated with increased risk of hypertension (odds ratio (OR)=1.8, 95% confidence interval (CI)=1.8-3.0), type 2 diabetes (OR=3.1, CI=1.4-6.9), parental history of hypertension (OR=1.3, CI=1.0-1.8) and parental history of type 2 diabetes (OR=1.7, CI=1.2-2.3). Thus, serum triglyceride levels may be valuable in the assessment of cardiovascular risk during young adulthood.

Rate of change in adiposity and its relationship to concomitant changes in cardiovascular risk variables among biracial (black-white) children and young adults: The Bogalusa Heart Study

To assess the annual rate of change in adiposity and its relationship to concomitant changes in cardiovascular risk variables during childhood and young adulthood, serial data on black and white children (n = 3,459; initial and follow-up mean age, 8.1 and 14.4 years) and young adults (n = 1,263; initial and follow-up mean age, 22.5 and 30.9 years) enrolled in the Bogalusa Heart Study were examined. Body mass index (BMI) and sum of subscapular and triceps skinfolds were used as indicators of adiposity. In addition, measurements were made of systolic and diastolic blood pressure and fasting levels of low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, triglycerides, insulin, and glucose. Annualized rate of change for each variable was estimated. The rate of increase in adiposity was significantly more pronounced during childhood versus adulthood. Race difference (blacks > whites) in the rate of increase in adiposity was seen only among females. Females, black females in particular, displayed greater rate of increase in adiposity than males. In a multivariate analysis, the rate of increase in adiposity was related independently of baseline age and baseline adiposity to adverse changes in measured cardiovascular risk variables, except glucose. Many of these associations were modulated significantly by race, sex, and age group. The impact was relatively greater for blood pressure and LDL cholesterol in adults and for triglycerides in children. The changes in blood pressure, LDL cholesterol, and HDL cholesterol were greater in whites, while the rate of increase in insulin was greater in blacks. Females displayed greater changes in blood pressure, HDL cholesterol, and insulin. On the other hand, the rate of increase in triglycerides was greater in males. These results indicate that increases in adiposity regardless of initial status of body fatness alter cardiovascular risk variables towards increased risk beginning in childhood, and that this deleterious trend underscores the importance of weight control early in life.

Plasma renin activity and insulin resistance in African American and white children: the Bogalusa Heart Study

Recent studies have suggested that the renin-angiotensin system is a feature of the insulin resistance syndrome. However, whether such a relationship occurs in childhood and in both African Americans and whites is not clear. We examined this issue in a sample of 264 African American and white children aged 7 to 16 years who participated in a cross-sectional survey of the Bogalusa Heart Study (n = 3,524). Children were selected using a stratified random sampling procedure based on race-, age-, and sex-specific percentiles of diastolic blood pressure. Whites had higher plasma renin activity than African Americans (7.1 +/- 3.6 ng/mL/h v 5.3 +/- 3.5 ng/mL/h, P < .01). Renin activity correlated with blood pressure (BP) (r = 0.21, P < .05) and insulin resistance index defined by post-glucose 1-h insulin X 1-h glucose (r = 0.19, P < .05) only in white children. Other components of insulin resistance syndrome (percent body fat, systolic blood pressure, high-density lipoprotein cholesterol, and triglycerides) showed no relation to renin in both races using univariate analyses. The distribution of insulin resistance index and renin activity among children with elevated BP (above 90th percentile) showed that the percentage of children with both high insulin resistance index and renin values was significantly greater in whites than in African Americans (45.6% v 23.3%, P < .05). A multivariate factor analysis of risk variables of insulin resistance syndrome resulted in clusters of BP/adiposity (factor 1), lipids/adiposity (factor 2), and insulin resistance/renin/adiposity (factor 3) in white children, with adiposity linking the three factors. However, a different pattern emerged in African American children for factor 2 and factor 3, and renin was not part of the cluster in any of the three factors. These observations suggest that renin may be a component of insulin resistance syndrome detectable in early life only in whites.

Distribution and correlates of high-density lipoprotein subclasses among children and adolescents

Levels of high-density lipoprotein (HDL) cholesterol among children vary by sex and race/ethnicity and are correlated with age, obesity, and other characteristics. Several studies of adults have indicated that atherogenicity of HDL particles may vary by size, but there is little information on the distribution and correlates of HDL subfractions in early life. We used nuclear magnetic resonance (NMR) spectroscopy to determine the mean HDL particle size and levels of 3 HDL subclasses among 10- to 17-year-olds (n = 918). We found the mean HDL particle size to be (1) inversely associated with age among boys, (2) larger among girls than boys, and (3) larger among black children than among white children. These associations with particle size reflected contrasting associations with various HDL subclasses; among boys, for example, levels of large HDL decreased with age, whereas levels of small HDL remained constant (black boys) or tended to increase (white boys). Furthermore, relative weight and levels of both triglycerides and low-density lipoprotein (LDL) cholesterol were associated inversely with levels of large HDL, but positively with levels of small HDL. These contrasting associations suggest that the role of HDLC in coronary heart disease (CHD) may be more complex than previously thought, and that the analysis of HDL subclasses may improve the accuracy of CHD prediction.

Risk variables of insulin resistance syndrome in African-American and Caucasian young adults with microalbuminuria: the Bogalusa Heart Study

Microalbuminuria is a strong predictor of cardiovascular disease. Previous studies are inconsistent regarding the relationship between microalbuminuria and insulin resistance syndrome. Therefore, we examined this relationship in 1031 young adults (61% Caucasian, 39% African-American) aged 19 to 32 years. Individuals with either urinary albumin to creatinine ratio at or above the 90th percentile (age, race, and gender specific) or urinary albumin level at or above 30 mg/L were considered as having slightly elevated albumin excretion (microalbuminuria). The multiple risk variables of insulin resistant syndrome measured include body mass index, waist circumference, blood pressure (BP), triglycerides, high-density lipoprotein (HDL) cholesterol, glucose, insulin, insulin resistance index (calculated from a homeostasis model assessment equation), and uric acid. After controlling for age and gender, African-Americans with microalbuminuria by either measure had higher mean systolic (P < .001) and diastolic (P < .05) BP, prevalence of hypertension (P < .05), and, contrary to expectations, HDL cholesterol (P < .05) than those without this condition. On the other hand, Caucasians showed no such associations. In African-Americans, the above differences in BP levels persisted when hypertensive subjects were excluded. None of the other risk variables displayed any relation to microalbuminuria in both races. These results suggest that microalbuminuria is not necessarily an intrinsic component of the insulin resistance syndrome, at least in the young adult age. Furthermore, the observed association between hypertension and microalbuminuria among young African-Americans may reflect early evidence of renal dysfunction due to the burden of elevated BP in this group.

Levels and correlates of LDL and VLDL particle sizes among children: the Bogalusa heart study

Levels of lipids and lipoproteins among children vary by sex and race/ethnicity, and are correlated with age, obesity, and other characteristics. There is, however, little information on the distribution and correlates of low-density lipoprotein (LDL) and very-low-density lipoprotein (VLDL) subclasses in early life. We used nuclear magnetic resonance (NMR) spectroscopy to determine mean LDL and VLDL particle sizes among 10- to 17-year-olds (n=918) who participated in the 1992-94 examination of the Bogalusa heart study. As compared with girls, boys had a smaller (0.1 nm) mean LDL particle size and a larger (0.9 nm) mean VLDL size; furthermore, the average size of VLDL particles increased with age among white boys but not among other children. Although there were also black/white differences in particle sizes, with black children having larger LDL and smaller VLDL particles, these racial contrasts could be attributed to differences in lipid levels. Levels of triglycerides, insulin, and relative weight were associated with the size of VLDL (positive) and LDL (negative) particles. These results suggest that the analysis of lipoprotein subclasses may provide a better understanding of the role of various risk factors in the development of coronary heart disease

Risk of type 2 diabetes mellitus in young adults from a biracial community: the Bogalusa Heart Study

BACKGROUND

Since type 2 diabetes has a strong familial component, characteristics of young adult offspring of type 2 diabetics were examined in a community sample to determine early abnormalities in black and white persons at risk.

METHODS

The sample consisted of 1,338 fasting young adults (72% white, 28% black) aged 19 to 37 years from a biracial community, including those with positive parental history of type 2 diabetes (one offspring per family, n = 230) or conditions of impaired fasting glucose and type 2 diabetes (n = 22).

RESULTS

Positive family history of diabetes or impaired fasting glucose and type 2 diabetes in young adults of both races were significantly associated with adverse profiles of measures of obesity and abdominal fat (body mass index, triceps and subscapular skinfolds, waist circumference, and abdominal height), systolic and diastolic blood pressures, serum total cholesterol, triglycerides, VLDL cholesterol, and HDL cholesterol, and indicators of glucose homeostasis (plasma glucose and insulin and insulin resistance index). The magnitude of the differences in obesity and abdominal fat measures and plasma glucose between individuals with and without parental diabetes was greater among blacks versus whites (P = 0. 047-0.004). Further, black offspring of both diabetics and non-diabetics had unfavorable profiles of obesity and abdominal fat measures, blood pressure, insulin, and insulin resistance index (P = 0.0001). In a multivariate analysis, adiposity measured as body mass index (P = 0.03) and plasma glucose (P = 0.003) emerged as the two independent characteristics that distinguished those with parental diabetes from those without parental disease. Insulin (P = 0.0001) and the insulin resistance index (P = 0.0001) were independently associated with conditions of impaired fasting glucose or type 2 diabetes.

CONCLUSIONS

The risk factors of young adults with parental type 2 diabetes or conditions of impaired fasting glucose and type 2 diabetes can be detected early. These observations have implications for early prevention and intervention, especially for blacks.

Temporal relation between blood pressure and serum creatinine in young adults from a biracial community: the Bogalusa Heart Study

It is well recognized that end-stage renal disease (ESRD) is associated with accelerated and malignant hypertension. The association of renal disease and what is considered as normal blood pressure is still not clear. The present study examined the temporal relation between blood pressure and renal function reflected by serum creatinine in a biracial (black-white) community-based population enrolled in the Bogalusa Heart Study. The study included 662 young adults aged 19 to 32 years, (white men, n = 188; white women, n = 289; black men, n = 67; and black women, n = 118) who were followed for an average of 7.4 years. In black men, partial correlation adjusted for age, body mass index, serum glucose, uric acid, and cigarette smoking showed that baseline systolic and diastolic blood pressure are not significantly related to baseline serum creatinine, but significantly related to serum creatinine at follow-up (r = 0.38, P = .008 and r = 0.42, P = .003, respectively). Multivariate regression analysis further showed a significant prediction of serum creatinine at follow-up by baseline systolic and diastolic blood pressure (0.031 mg/dL and 0.037 mg/dL rise in follow-up serum creatinine for every 10 mm Hg increase in systolic (P = .000) and diastolic (P = .001) blood pressure at baseline, but not the other way around. Other race and sex groups did not show such significant temporal relations. We conclude that in young black men, higher blood pressure levels within normal range precede and explain part of the increase in serum creatinine, a measure of decline in renal function. Thus, our results underscore the beneficial effect of maintaining blood pressure levels lower than what is considered as the upper normal limit, particularly in black men.

Age-related patterns of the clustering of cardiovascular risk variables of syndrome X from childhood to young adulthood in a population made up of black and white subjects: the Bogalusa Heart Study

The age-related patterns of clustering of cardiovascular risk variables of Syndrome X from childhood to adulthood were examined in a community-based sample of black and white children (aged 5-10 years, n = 2,389), adolescents (aged 11-17 years, n = 3,371), and young adults (aged 18-37 years, n = 2,115). In the analysis of clustering, insulin resistance index, BMI, triglycerides/ HDL cholesterol ratio, and mean arterial pressure were used either as categorical variables (age-, race- and sex-specific values >75th percentiles) to calculate risk ratios (observed frequency/expected frequency) or as continuous variables (normal scores based on ranks) to compute intraclass correlations. In the total sample, the risk ratio for clustering of adverse levels of all 4 variables was 9.8 for whites (P < 0.01) versus 7.4 for blacks (P < 0.01); the intraclass correlation was 0.33 for whites (P < 0.001) versus 0.26 for blacks (P < 0.001). Both the risk ratio and intraclass correlation were significantly higher in whites than in blacks in the total sample. The intraclass correlations of the 4 variables were significant (P < 0.001) in all race and age-groups, and they were higher during preadolescence and adulthood than during adolescence. Furthermore, unlike risk ratios, intraclass correlations showed a continuous increase with age during adulthood. When BMI was adjusted, the intraclass correlations involving the other 3 variables were reduced by approximately 50%, and the age-related pattern was no longer evident. These results suggest that the degree of clustering of risk variables of Syndrome X varies with age from childhood to adulthood and is likely influenced by the age-related changes in obesity and the attendant insulin resistance.

Black/white differences in relative weight and obesity among girls: the Bogalusa Heart Study

BACKGROUND AND OBJECTIVE

Although black women have a higher prevalence of overweight and obesity than do white women, it is unclear if a similar pattern exists among youths. We therefore examined the development of black/white differences in relative weight and adiposity among 5 to 17-year-old girls.

METHODS

Cross-sectional analyses of 4542 black and 4542 white girls who were examined between 1973 and 1994. Quetelet Index (kg/m(2)), Rohrer Index (kg/m;s(3)), and height-adjusted weight were used as measures of relative weight, and subscapular and triceps skinfolds as measures of adiposity. Breast development was used as an index of sexual maturation.

RESULTS

On average, black girls were 1 to 3 kg heavier than were similarly aged white girls, and before adolescence, they were 2 to 3 cm taller. After adjusting for differences in height, the mean relative weight of black girls was consistently greater than that of white girls only after age 13; furthermore, sexual maturation was a stronger correlate of relative weight among black girls than among white girls. Comparable differences were seen for the subscapular skinfold thickness, but white girls consistently had a thicker mean triceps skinfold than did black girls.

CONCLUSION

Sexual maturation should be considered in comparisons of relative weight and obesity among youths, and as compared with white girls, black girls do not have a higher mean relative weight until adolescence. The use of different indices of overweight and adiposity can lead to contrasting results, with simple comparisons of Quetelet Index tending to overstate the relative weights of taller children.

Secular trends in height among children during 2 decades: The Bogalusa Heart Study

OBJECTIVE

To examine trends in height among 5- to 17-year-old children between 1973 and 1992.

DESIGN

A panel design consisting of 7 cross-sectional surveys.

PARTICIPANTS

All schoolchildren residing in Bogalusa, La, were eligible. A total of 24 070 examinations were performed.

RESULTS

During the study period, the mean height of schoolchildren increased by 0.70 cm per decade independently of race, sex, and age. Trends were most pronounced among preadolescents, blacks, and boys, with 9- to 12-year-old black boys showing a height increase of 1.8 cm per decade. We observed a decrease in the number of relatively short children (<10th percentile of height) and an increase in the number of tall children (>90th percentile of height). Because a secular trend was not seen among the 15- to 17-year-old children, our findings likely reflect an acceleration of maturation.

CONCLUSIONS

It has generally been assumed that secular increases in height among schoolchildren in the United States ceased by the mid-1900s. Our findings, which may be due to various environmental factors, demonstrate that care must be taken when using nonconcurrent reference data to assess the growth of children. Additional study is needed to determine if these secular trends are continuing and to examine possible explanations and consequences of these trends.

Cardiovascular risk factors clustering features of insulin resistance syndrome (Syndrome X) in a biracial (Black-White) population of children, adolescents, and young adults: the Bogalusa Heart Study

Recently, independent factors representing different features of insulin resistance syndrome (Syndrome X) have been identified by factor analysis in middle-aged and elderly adult populations. In this study, factor analysis was applied to the clustering characteristics of Syndrome X in a biracial (Black-White) community-based population of 4,522 children (ages 5-11 years), adolescents (ages 12-17 years), and young adults (ages 18-38 years) from the Bogalusa Heart Study who were screened during 1988-1996. Ponderal index (weight (kg)/height (m)3), levels of insulin, glucose, triglycerides, and high density lipoprotein cholesterol, and systolic and diastolic blood pressure were used as measures of components of Syndrome X. No evidence was found to support a one-factor hypothesis for this syndrome, but factor analysis yielded two uncorrelated factors (factor 1: insulin/lipids/glucose/ponderal index; factor 2: insulin/blood pressure). These two factors explained 54.6% of the total variance in the entire sample. The factor loading patterns were very similar in all race and age groups, based on high values of coefficients of congruence (0.89-1.0). These results suggest that Syndrome X is characterized by the linking of a metabolic entity (hyperinsulinemia/insulin resistance, dyslipidemia, and obesity) to a hemodynamic factor (hypertension) through shared correlation with hyperinsulinemia/insulin resistance, and that the clustering features are independent of sex and age in both Black and White populations.

Secular trend of earlier onset of menarche with increasing obesity in black and white girls: the Bogalusa Heart Study

Secular trends in onset of menarche and obesity were examined 14 years apart in two biracial (black-white) cohorts of girls aged 8 to 17 under study for cardiovascular risk. The first cohort (N=1,190, 64% white) was examined in 1978-1979, the second (N=1,164, 57% white) in 1992-1994. The second cohort was heavier in terms of body weight and Rohrer index (weight/height3) than the first (P<0.001), except among black girls aged 12 to 13 years. Subscapular skinfold thickness increased in the second cohort of all ages (P<0.0001), while increases in triceps skinfold were less marked. The onset of menarche occurred at an earlier age in the second cohort compared with the first cohort (P<0.0001), both in black girls (11.4+/-1.3 vs 12.3+/-1.4 years) and white girls (11.5+/-1.3 vs 12.3+/-1.3 years). Furthermore, twice as many girls in the second cohort had reached menarche by ages younger than 12 years (P<0.001). All of these obesity measures were significantly associated with the age of menarche in both cohorts (P<0.001) adjusting for height, race and age at examination. These results suggest that this secular trend toward increasing frequency of early onset of menarche may be the result of increasing obesity noted in girls of both races. Since increases in body fatness and related early onset of menarche are risk factors for disorders in adult life including cardiovascular disease and breast cancer, the secular trend in the increasing incidence of obesity throughout the United States is becoming a major public health problem.

The association of cardiovascular risk factor clustering related to insulin resistance syndrome (Syndrome X) between young parents and their offspring: the Bogalusa Heart Study

Cardiovascular risk factor clustering related to insulin resistance syndrome (Syndrome X) was examined in a community-based sample of 599 genetically unrelated school-aged children (5-17 years) and their parents. Risk factors used as components of Syndrome X included hyperinsulinemia, obesity, dyslipidemia and high blood pressure defined by values above the age-, sex- and race-specific 75th percentiles of fasting insulin, body mass index, triglycerides/high-density lipoprotein cholesterol ratio and mean arterial pressure, respectively. Based on observed to expected ratio there was an excess of parents (father and/or mother) and their offspring with clusters of three or four disorders (P < 0.05-0.001). In contrast, the number of parents and offspring with two disorders was significantly lower than expected by chance alone (P < 0.05-0.01). Based on paternal, maternal, and parental Syndrome X, the odds ratios (95% confidence interval) for offspring having the same cluster were 7.2 (1.9-27.2), 8.6 (3.1-23.6) and 7.9 (3.5-18.1), respectively. In terms of individual risk factors of parents used as predictors, adverse levels of their insulin and BMI significantly increased the risk of offspring having Syndrome X (P < 0.01-0.001), whereas the effect of parental insulin was considerably reduced after parental BMI was adjusted for. In contrast, parental dyslipidemia and high blood pressure were not associated with the occurrence of Syndrome X in their offspring. These results confirm the familial nature of Syndrome X and suggest that conditions of obesity and the attendant hyperinsulinemia in parents may underlie this familial association.

Temporal association between obesity and hyperinsulinemia in children, adolescents, and young adults: the Bogalusa Heart Study

Obesity is generally associated with hyperinsulinemia. However, whether obesity precedes or follows hyperinsulinemia is not clear. The present study examined the temporal nature of the association between obesity and hyperinsulinemia in a biracial (black-white) community-based population enrolled in the Bogalusa Heart Study. Three longitudinal cohorts of children (n = 427; baseline age, 5 to 7 years), adolescents (n = 674; baseline age, 12 to 14 years), and young adults (n = 396; baseline age, 20 to 24 years) were selected retrospectively, with a follow-up period of approximately 3 years. In general, longitudinal changes in the mean body mass index (kilograms per meter squared), an indicator of adiposity, and fasting insulin level did not parallel each other. In a bivariate analysis, baseline insulin levels correlated significantly with the follow-up body mass index in adolescents and adults, but not in children. On the other hand, the baseline body mass index correlated significantly with follow-up insulin levels in all cases. Logistic regression analysis showed that the proportion of subjects who developed obesity (body mass index > 75th percentile, specific for age, race, gender, and survey year) at follow-up study increased significantly across baseline quintiles (specific for age, race, gender, and survey year) of insulin only among adolescents, irrespective of race and gender. This relationship disappeared after adjusting for the baseline body mass index. By contrast, a significant positive trend between baseline quintiles of the body mass index and incidence of hyperinsulinemia (> 75th percentile) at follow-up study was noted among all age groups independent of race, gender, and baseline insulin levels. Further, in a multiple stepwise regression model, the best predictor of the follow-up insulin level was the baseline body mass index in children and adults and the baseline insulin in adolescents. The baseline body mass index was the best predictor of the follow-up body mass index in all three age groups. These results, by showing the temporal nature of the relation between obesity and hyperinsulinemia beginning in childhood, support the role of obesity in the development of hyperinsulinemia.