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Biomedical subjects

S R Daniels

Publications and source records attributed to S R Daniels.

At least 37 records · Page 2Linked to original sources
PubMed2000

Severe left ventricular hypertrophy in pediatric dialysis: prevalence and predictors.

Left ventricular hypertrophy (LVH) has been recognized as an independent risk factor for cardiovascular morbidity and mortality in adults with end-stage renal disease. However, the prevalence and severity of LVH in children on chronic dialysis therapy is not well established. Retrospectively, 64 chronic dialysis patients, aged 20 months to 22 years, on chronic dialysis had echocardiographic evaluation of LV mass (LVM) and geometry. Forty-eight (75%) children had LVH, including 22 of 26 (85%) on hemodialysis (HD) and 26 of 38 (68%) on peritoneal dialysis (PD). The prevalence of LVH in patients on HD was significantly higher than those on PD (P=0.02). Abnormal LV geometry was found in 51 of 64 (80%) patients: 25 patients (39%) had eccentric hypertrophy, 3 (5%) had concentric remodelling, and 23 (36%) had concentric LVH. Twenty-six children (41%) had severe LVH, defined as LVM index greater than 51 g/m2.7, which is associated with a fourfold greater risk for development of cardiovascular disease in adults. Patients with severe LVH had a significantly lower hemoglobin level (P=0.027) and longer duration of renal disease prior to the start of dialysis therapy (P=0.003) than patients without LVH. Multiple logistic regression analysis revealed HD as opposed to PD as a significant independent predictor for severe LVH (P=0.036). Higher systolic blood pressure remained in the final model as an independent predictor with a borderline level of significance (P=0.065). The results indicate that severe LVH and abnormal left ventricular geometry are common in young dialysis patients. Better control of blood pressure, anemia, and hypervolemia may be important in prevention or improving LVH.

Adolescent↗
PubMed2000

Relation of left ventricular chamber and midwall function to age in normal children, adolescents and adults.

BACKGROUND: The goal of this study was to identify the effect of body growth and aging, and normal limits of the relation of left ventricular endocardial and midwall shortening to wall stress. METHODS: Endocardial and midwall shortening and circumferential end-systolic stress were assessed in 388 normotensive, normal-weight adults (226 men, 162 women, age 18 to 85 years) and 332 children and adolescents (180 males, 152 females, age 4 to 17 years) by two-dimensional targeted M-mode echocardiography and cuff blood pressure measurements. RESULTS: End-systolic stress decreased with age in children and adolescents (p < 0.001), but not during adulthood and maturity. The negative relation of endocardial shortening to end-systolic stress was stronger in adults than in children and adolescents (slope difference p < 0.005). The negative relation of midwall shortening to end-systolic stress was negligible in children and adolescents (r = -0.07, p = 0.18), whereas it was more evident, although weak, in adults (r = -0.14, p < 0.007). For a given level of end-systolic stress, endocardial shortening decreased by 0.32%/year in children and adolescents (multiple r = 0.51, p < 0.0001) and by 0.05%/year in adults, whereas midwall shortening decreased by 0.26%/year during body growth and by 0.02%/year in adults. CONCLUSIONS: In the presence of normal blood pressure and normal weight, the relations between left ventricular wall stress and both chamber and myocardial function are weakly but significantly influenced by age. Left ventricular chamber function is markedly influenced by wall stress, while this influence is reduced for left ventricular wall mechanics.

Adolescent↗
PubMed1999

Serum glutathione in adolescent males predicts parental coronary heart disease.

BACKGROUND: Traditional risk factors account for only half of the morbidity and mortality from coronary heart disease (CHD). There is substantial evidence that oxidative injury plays a major role in the atherosclerotic process. Thus, antioxidants may protect against development of atherosclerosis. Glutathione, an intracellular tripeptide with antioxidant properties, may be protective. METHODS AND RESULTS: This case-control study compared total serum glutathione (tGSH) in 81 adolescent male offspring of parents with premature CHD (ie, before 56 years of age) and 78 control male offspring of parents without known or suspected CHD. Case offspring had significantly lower tGSH than control offspring. In multiple logistic regression with parental CHD status as the dependent variable, age entered as a covariate, and other CHD risk factors competing to enter the model as significant independent predictor variables, LDL cholesterol (odds ratio [OR], 2.15 [units=1.5 SD]; 95% CI, 1.21 to 3.82), tGSH (OR, 0.40; 95% CI, 0.22 to 0.71), HDL cholesterol (OR, 0.42; 95% CI, 0.22 to 0.78), and total serum homocysteine (OR, 2.6; 95% CI, 1.35 to 5.02) entered the model as significant predictors of parental CHD status. CONCLUSIONS: Low tGSH in adolescent boys is a significant independent predictor of parental CHD, in addition to elevated LDL cholesterol, low HDL cholesterol, and elevated total serum homocysteine concentrations.

Adolescent↗
PubMed1999

Association of body fat distribution and cardiovascular risk factors in children and adolescents.

BACKGROUND: Obesity is associated with increased risk of cardiovascular disease in adults and less favorable cardiovascular risk factor status in children and adolescents. In adults, fat distribution has been shown to be related to lipid and lipoprotein concentrations, blood pressure levels, and left ventricular mass. These relationships have not been extensively studied in young subjects. METHODS AND RESULTS: This was a cross-sectional study of 127 children and adolescents 9 to 17 years of age. Dual-energy x-ray absorptiometry was used to measure total and regional fat mass. The dependent variables were fasting lipid and lipoprotein concentrations, systolic and diastolic blood pressures, and left ventricular mass. There were significant (P<0.05) univariate correlations between fat distribution and log triglycerides (r=0.27), log HDL cholesterol (r=-0.23), systolic blood pressure (r=0.26), and left ventricular mass (r=0.37). Multiple regression analysis showed that the significant independent correlates for triglycerides and HDL cholesterol were age and fat distribution; for systolic blood pressure, height and fat distribution; and for left ventricular mass, height, race, sex, and fat distribution. CONCLUSIONS: These results demonstrate that fat distribution is a more important independent correlate of cardiovascular risk factors than percent body fat in children and adolescents. Greater deposition of central fat (an android fat pattern) is associated with less favorable plasma lipid and lipoprotein concentrations, blood pressure, and left ventricular mass.

Adipose Tissue↗
PubMed1999

Pathogenesis of dilated cardiomyopathy: molecular, structural, and population analyses in tropomodulin-overexpressing transgenic mice.

Dilated cardiomyopathy is characterized by decreased contractile function and loss of myofibril organization. Previously unexplored structural and molecular events that precede and initiate dilation can now be studied in tropomodulin-overexpressing transgenic (TOT) mice exhibiting progressive dilated cardiomyopathy. Onset of dilation did not correspond to a change in transgene expression levels, which were more than threefold above normal at birth and remained elevated throughout postnatal life. Similarly, mitogen-activated protein kinase activation (p38, ERK1/ERK2, JNK1/JNK2) was not associated with dilation. In contrast, calcineurin was activated before dilation, presumably due to doubling of intracellular diastolic calcium levels in TOT cardiomyocytes. Amplitude of systolic calcium transients was greatly increased as well, demonstrating the novel and unique calcium handling profile of TOT cardiomyocytes. Loss of myofibril organization was not apparent by confocal microscopy until over 1 week after birth, although neonatal sarcomeric abnormalities were revealed by ultrastructural analysis. Rapid postnatal increases in heart:body weight ratio at 1.5 weeks were followed by two waves of mortality between 2 and 3 weeks after birth coincident with maturational stress. Ultimately, TOT pathogenesis is a compensatory response to altered sarcomeric structure driven by calcineurin activation within days after birth, making TOTs an excellent paradigm for studying the role of calcium overload in dilated cardiomyopathy.

Animals↗
PubMed1999

Overweight, fat patterning, and cardiovascular disease risk factors in black and white boys.

PURPOSE: To evaluate the relationships of overweight and fat patterning with cardiovascular disease (CVD) risk factors in black and white boys. DESIGN: Cross-sectional analysis of CVD risk factors by weight and central adiposity groups in black and white boys, aged 10 to 15 years. Mean adiposity, lipid, and blood pressure variables were compared between weight and central adiposity groups within race by using linear regression models. Observed clustering of risk factors within weight and adiposity groups was compared with the expected clustering under an assumption of no association. RESULTS: Within each racial group, overweight boys had greater skinfolds, lower high-density lipoprotein cholesterol levels, higher low-density lipoprotein cholesterol and triglyceride levels, and higher systolic and diastolic blood pressure than non-overweight boys. Among overweight boys, greater central adiposity was associated with higher risk factor levels and increased clustering of risk factors. CONCLUSION: Overweight and central adiposity together profoundly affect CVD risk factor levels and risk factor clustering in black and white boys.

Adipose Tissue↗
PubMed1999

Overweight, fat patterning, and cardiovascular disease risk factors in black and white girls: The National Heart, Lung, and Blood Institute Growth and Health Study.

OBJECTIVE: To determine the association of overweight and central adiposity with cardiovascular disease risk factors in black and white 9- and 10-year-old girls. DESIGN: Cross-sectional analysis of baseline data collected from participants in the National Heart, Lung, and Blood Institute Growth and Health Study. Girls were classified as overweight or not with the use of the age- and sex-specific 85th percentiles of the body mass index (kilograms per square meter) distributions from the combined NHANES (I and II) data set. Mean indexes of central adiposity, blood pressure levels, and lipid concentrations and the clustering of risk factors based on published cut points were compared between weight groups by race and by central adiposity group within weight and race groups. RESULTS: Overweight was associated with increased risk factor levels and with increased clustering in both black and white girls. Among overweight girls greater central adiposity was associated with higher risk factor levels and increased clustering. CONCLUSIONS: Given the associations between cardiovascular disease risk factors and both overweight and central adiposity, the secular trends toward increased obesity in American youth portend a worsening of cardiovascular disease risk profiles.

Adipose Tissue↗
PubMed1999

Sex and race differences in cardiovascular disease risk factor changes in schoolchildren, 1975-1990: the Princeton School Study.

OBJECTIVES: This study was done to assess changes in obesity and risk factors for cardiovascular disease (CVD) in Black and White children from 1975 through 1990. METHODS: A cross-sectional study of body composition and CVD risk factors conducted in a school district as part of the Lipid Research Clinics (LRC) Program Prevalence Study (1973-1975) was compared with a later study (1989-1990) conducted in the same school district, which remained demographically stable. The studies included 1456 third- and fifth-grade students and 300 LRC subjects within the same age ranges. RESULTS: Students in the 1989-1990 study had a significantly higher mean body mass index (BMI), total blood cholesterol concentration, and systolic and diastolic blood pressures and marginally higher resting heart rates than those in the earlier study. The prevalence of obesity increased from 12.5% to 25.3%, and of hypercholesterolemia from 8.0% to 14.8%. Black females had the largest increase in BMI and resting heart rate and the highest prevalence of elevated total cholesterol in the 1989-1990 study. CONCLUSIONS: The results of this study suggest a secular trend toward increased obesity in children and portend the potential development of a public health problem that could reverse the recent decline in morbidity from CVD.

Adolescent↗
PubMed1998

Left ventricular geometry and severe left ventricular hypertrophy in children and adolescents with essential hypertension.

BACKGROUND: Left ventricular (LV) hypertrophy has been established as an independent risk factor for cardiovascular disease in adults. Recent research has refined this relationship by determining a cutpoint of 51 g/m(2.7) for LV mass index indicative of increased risk and defining LV geometric patterns that are associated with increased risk. The purpose of this study was to evaluate severe LV hypertrophy and LV geometry in children and adolescents with essential hypertension. METHODS AND RESULTS: A cross-sectional study of young patients (n=130) with persistent blood pressure elevation above the 90th percentile was conducted. Nineteen patients (14%) had LV mass greater than the 99th percentile; 11 of these were also above the adult cutpoint of 51 g/m(2.7). Males, subjects with greater body mass index, and those who had lower heart rate at maximum exercise were at significantly (P<.05) higher risk of severe LV hypertrophy. In addition, 22 patients (17%) had concentric LV hypertrophy, a geometric pattern that is associated with increased risk of cardiovascular disease in adults. Seven patients had LV mass index above the cutpoint and concentric hypertrophy. No consistent significant determinants of LV geometry were identified in these children and adolescents with hypertension. CONCLUSIONS: Severe LV hypertrophy and abnormal LV geometry are relatively prevalent in young patients with essential hypertension. These findings suggest that these patients may be at risk for future cardiovascular disease and underscore the importance of recognition and treatment of blood pressure elevation in children and adolescents. Weight loss is an important component of therapy in young patients with essential hypertension who are overweight.

Adolescent↗
PubMed1998

Nocturnal blood pressure in young patients with insulin-dependent diabetes mellitus: correlation with cardiac function.

Lack of a decline in nocturnal blood pressure is associated with an adverse effect on end organs in adults with insulin-dependent diabetes mellitus (IDDM). The role of the decline in nocturnal blood pressure in young patients with IDDM is not known. We studied 25 white subjects with IDDM (age = 20.8 +/- 3.7 years, mean +/- SD), 8 of whom were female. The duration of IDDM in these subjects was 12.9 +/- 5.4 years (mean +/- SD). We determined the values for glycosylated hemoglobin (HgbA1), 24-hour ambulatory blood pressure, diastolic cardiac function (the ratio of peak E wave to peak A wave velocity (E/A) and indexed peak filling rate ¿PFR/SV¿ by Doppler echocardiography), and albumin excretion rate. The HgbA1 level was 10.9% +/- 1.9% (mean +/- SD; normal range = 4.5%-8.5%). The HgbA1 concentration was inversely correlated (p < 0.005) with the decline in systolic (r = 0.57) and diastolic (r = -0.55) nocturnal blood pressure. Diastolic cardiac dysfunction ¿E/A ratio [r = 0.42, p < 0.03) and PFR/SV (r = 0.52, p < 0.01)¿ correlated with a smaller decrease in nocturnal diastolic blood pressure. An inverse correlation between decline in nocturnal systolic blood pressure and log albumin excretion rate (r = -0.37, p = 0.07) approached statistical significance. We conclude that poor glycemic control adversely affects nocturnal blood pressure and that the latter may play an important role in cardiac and possibly renal dysfunction in early IDDM.

Adolescent↗
PubMed1998

Prediction of adult hypertension by K4 and K5 diastolic blood pressure in children: the Bogalusa Heart Study.

OBJECTIVE: The objective of this study was to examine the reproducibility of K4 and K5 diastolic blood pressure measurements and the ability to predict adulthood values. STUDY DESIGN: The Bogalusa Heart Study is a long-term epidemiologic study of cardiovascular disease risk factors from birth to early adulthood conducted in the biracial (one third black, two thirds white) community of Bogalusa, Louisiana. Analyses included blood pressure measurements taken on 12,139 subjects during multiple cross-sectional screenings from 1973 to 1994; 20% (N = 2530) had measurements taken as a child, ages 4 to 18 years, and during adulthood, ages 19 to 32 years. Six resting blood pressure measurements were taken by trained observers with mercury sphygmomanometers at each screening with K1, K4, and K5 recorded. Variance components analysis was used to evaluate the reliability of K4 and K5. RESULTS: The total variance was larger for K5 (253 mm Hg2) than for K4 (109 mm Hg2) at age 5 years. Variance for both K4 and K5 decreased with age. The interobserver variability was larger for K5 (more than 50% vs 40%). Childhood K4 (vs childhood K5) was better correlated with adult K1 and K5 (0.28 vs 0.11 for K1; 0.33 vs 0.25 for K5 at age 11 to 13 years). K4 was also shown to have a higher odds ratio for predicting adult hypertension than K5 (1.57 vs 1.14 at age 11 to 13 years). CONCLUSION: During childhood K4 is a more reliable measure of diastolic blood pressure than K5. K4 diastolic blood pressure measured in childhood is a better predictor of adult hypertension.

Adolescent↗
PubMed1998

Percentiles for body mass index in U.S. children 5 to 17 years of age.

OBJECTIVES: It has been recommended that body mass index (BMI) (weight in kilograms/height in meter2) be used routinely to evaluate obesity in children and adolescents. This report describes the distribution of BMI in children and adolescents in the United States. METHODS: Standardized measurements of height and weight from 9 large epidemiologic studies including 66,772 children age 5 to 17 years were used to develop tables for the distributions of BMI that are age, race, and gender specific. RESULTS: The mean BMI increases with age and is slightly higher for girls than boys. Mean BMI for black and Hispanic girls was noticeably higher than for white girls. The percentiles of BMI are consistently higher than those based on the NHANES I measures, particularly for the 95th percentile. The proportion of obese children compared with NHANES I standards is higher and is highest for Hispanic boys and black and Hispanic girls. CONCLUSION: The tables and figures will allow pediatricians to determine the relative ranking of BMI for patients compared with values derived from a large sample of healthy children and adolescents. The identified gender and ethnic differences may be guides to understanding the cause and prevention of obesity.

Adolescent↗
PubMed1998

Effect of veno-venous ultrafiltration on myocardial performance immediately after cardiac surgery in children. A prospective randomized study.

OBJECTIVES: This study sought to evaluate the effects of veno-venous ultrafiltration on myocardial contractility in children undergoing cardiopulmonary bypass (CPB) for repair of congenital heart defects. BACKGROUND: Ultrafiltration (UF) is currently used to diminish postoperative fluid accumulation following CPB in children. Previous reports indicate improvement in hemodynamics immediately after UF, but the mechanism of its action is unknown. METHODS: Twenty-three patients (ages 2 months to 9.1 years; 13 males, 10 females) underwent UF for 10 min after CPB. Twelve patients underwent UF immediately after CPB (Group A). They were studied: (1) before and (2) after CPB, (3) after UF, and (4) 10 min after UF. Eleven patients underwent UF 10 min after CPB (Group B). They were studied: (1) before and (2) after CPB, (3) after a 10-min delay before UF, and (4) after UF. Contractility was determined by the difference in the observed and predicted velocity of circumferential fiber shortening for the measured wall stress, using transesophageal echocardiography. Left ventricular wall thickness was also measured. RESULTS: There was significant improvement in contractility after UF in both groups (mean+/-SD, Group A: -0.28+/-0.13 to -0.01+/-0.21 circ/s, p < 0.05; Group B: -0.26+/-0.16 to -0.11+/-0.17 circ/s, p < 0.05). Myocardial thickness to cavity dimension decreased in both groups following UF (Group A: 0.19+/-0.04 to 0.14+/-0.03, p < 0.05; Group B: 0.18+/-0.04 to 0.14+/-0.03, p < 0.05). CONCLUSIONS: UF improves hemodynamics by improving contractility and possibly by reducing myocardial edema in children following cardiac surgery. Enhanced patient outcome after ultrafiltration may in part be due to these changes.

Cardiopulmonary Bypass↗
PubMed1998

Diastolic dysfunction in young patients with insulin-dependent diabetes mellitus as determined by automated border detection.

Diastolic dysfunction is an early harbinger for systolic dysfunction in insulin-dependent diabetes mellitus (IDDM). To determine the role of automated border detection (ABD) in detecting diastolic abnormalities and whether IDDM control correlates with abnormalities, 21 young IDDM patients (22 +/- 4 years old) and 19 control subjects underwent echocardiography. ABD indices included the percent contribution to total left ventricular filling of the three phases of diastole (rapid filling, diastasis, and atrial contraction) and peak filling rate. Doppler indices included E/A ratio and peak filling rate. Rapid filling phase was lower in the IDDM patients compared with control subjects (73% +/- 5% versus 80% +/- 5%, p = 0.0006), and atrial contraction filling was higher (19% +/- 4% versus 14% +/- 3%, p = 0.0003). Doppler indexes showed similar changes. Glycosylated hemoglobin, insulin dosage, and duration of IDDM since puberty were associated with filling abnormalities. Young patients with IDDM have increased atrial contraction and reduced rapid filling phases detected by automatic border detection, and these diastolic abnormalities are related to the diabetic disease process.

Adult↗