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Biomedical subjects

S R Srinivasan

Publications and source records attributed to S R Srinivasan.

At least 37 records · Page 2Linked to original sources
PubMed2001

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.

Adolescent↗
PubMed2001

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.

Adult↗
PubMed2001

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.

Adolescent↗
PubMed2001

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.

Adolescent↗
PubMed2001

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.

Journal Article↗
PubMed2001

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.

Adolescent↗
PubMed2001

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.

Adolescent↗
PubMed2000

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.

Adolescent↗
PubMed2000

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.

Adolescent↗
PubMed2000

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.

Adult↗
PubMed2000

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

Adolescent↗
PubMed2000

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.

Adult↗
PubMed2000

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.

Adult↗
PubMed2000

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.

Adolescent↗
PubMed1999

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.

Adolescent↗
PubMed1999

Plasma homocysteine distribution and its association with parental history of coronary artery disease in black and white children: the Bogalusa Heart Study.

BACKGROUND: Elevated homocysteine is associated with increased risk for coronary artery disease (CAD) in adults, but its distribution in children is not well documented. We examined the distribution of homocysteine in children and its relation to parental history of CAD. METHODS AND RESULTS: A subsample of 1137 children (53% white, 47% black) aged 5 to 17 years in 1992 to 1994 examined in the Bogalusa Heart Study (n=3135), including all with a positive parental history of CAD (n=154), had plasma homocysteine levels measured. Homocysteine correlated positively with age (r=0.16, P=0.001). No race or sex differences in homocysteine levels were observed; geometric mean (GM) levels were 5.8 micromol/L (95% CI, 5.6 to 6.1) among white males, 5.8 micromol/L (95% CI, 5.5 to 6.0) among white females, 5.6 micromol/L (95% CI, 5.4 to 5.8) among black males, and 5.6 micromol/L (95% CI, 5.4 to 5.9) among black females. Children with a positive parental history of CAD had a significantly greater age-adjusted GM homocysteine level (GM, 6.7 micromol/L; 95% CI, 6.4 to 7.1) than those without a positive history (GM, 5.6 micromol/L; 95% CI, 5.4 to 5.7); this relation was observed in each race-sex group. CONCLUSIONS: Higher homocysteine levels were observed among children with a positive family history of CAD. Additional studies should elucidate the contribution of genetic, dietary, and other factors to homocysteine levels in children.

Adolescent↗