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Biomedical subjects

L S Webber

Publications and source records attributed to L S Webber.

At least 199 records · Page 11Linked to original sources
PubMed1977

Anthropometric and maturation measurements of children, ages 5 to 14 years, in a biracial community--the Bogalusa Heart Study.

An epidemiological survey of anthropometric and maturation variables was conducted on 3,524 children from the biracial community of Bogalusa, Louisiana. These children, representing 93% of the population, were examined during the school year September 1973 through May 1974. Black boys differed slightly from white boys in height and weight; black girls were taller and heavier than white girls. The black children had longer upper arm lengths and smaller upper arm circumferences than the white children. The median ponderosity (weight divided by the cubed height) decreased with increasing heigth for the four race-sex groups, and a skewed distribution of ponderosity indicated an excess of heavy children among the tall. Based on the Tanner criteria for grading secondary sex characteristics, maturation occurred earlier in the more ponderous girls, although such was not the case for boys. Whereas the Tanner secondary sex characteristics appeared earlier in black girls, white girls reported menarche earlier. The racial and sexual differences known to exist in triceps skinfold were observed for this population. No statistically significant difference was observed overall for height and weight between children within this one community and those of the National Health Examination Survey. However, Bogalusa girls at the 95th percentile were heavier after age 11 than girls of the United States. Also, there was a tendency for white girls in this community to report reaching menarche at an earlier age than black girls, which contrasts slightly with the national sample.

Anthropometry↗
PubMed1977

Body height and body mass as determinants of basal blood pressure in children--The Bogalusa Heart Study.

Body height and body mass as determinants of basal blood pressure in children--The Bogalusa Heart Study. Am J Epidemiol 106:101-108, 1977. Risk factor variables for coronary artery disease were measured in a total biracial community study of 3524 children, ages 5-14 years. Anthropometric variables, serum lipids, and blood pressure (BP) were measured in a rigid randomized design. Blood pressure data were obtained with an automatic recording instrument that avoids excessive pressure readings in obese children by the use of an over-sized arm cuff bladder with a built-in infrasonic transducer. By reducing the anxiety of the child and by taking multiple readings, pressures were obtained that approached published basal levels. A multiple regression analysis showed that all measured variables could account for 39% of the systolic BP variation. Major determinants were based on weight (W) and height (H). The BP levels, when related to H and to a weight-height index (W/H3), suggest a strong influence of H and an additional influence of W/H3 on BP, both consistent and proportionate over the entire ranges of H and W/H3. The total spectrum of observed correlates of BP, resulting from the multiple regression analysis, suggests that the BP measured under basallike conditions increases as the child grows and is proportional to lean body mass and total body mass. Practical criteria for evaluating abnormal blood pressure levels in children should be based on normative values derived from body weight and body height rather than from age.

Adolescent↗
PubMed1977

A study of instruments in preparation for a blood pressure survey of children.

In preparation for the measurement of blood pressure in children of a total geographic community, several preliminary studies of the validity and reliability of various methods and instruments for indirect blood pressure measurements were performed. These studies included Graeco-Latin Square designs, examination of children in a field setting, and assessments of the replicability of reading automatically recorded blood pressures. Each of the studies was designed to monitor the validity and replicability of instruments, methods, and observers. Controlling for subject, we compute biases due to instrument, method and observer and, where possible, eliminated them in the enusing studies. One automatic instrument, the Physiometrics recorder, was selected and used in conducting epidemiologic studies where it complements the measurements by the mercury sphygmomanometer.

Blood Pressure Determination↗
PubMed1977

Hemoglobin levels in children from a biracial southern community.

Hemoglobin levels were determined for 4,081 children, ages 2 1/2-14 years, from a biracial southern community. Back children had lower levels of hemoglobin than white children at every age interval with a mean difference of 0.64 gm/dl. This diffence persisted even when comparing children from similar socioeconomic level households. If black children maintain lower hemoglobin levels consistent with optimum health than do white children, then different hemoglobin standards may be warranted for each race.

Adolescent↗
PubMed1976

Serum cholesterol and triglyceride levels in 3,446 children from a biracial community: the Bogalusa Heart Study.

Serum lipid profiles of 3,446 (91% of population) children, ages 5-14 years, were determined in a biracial community (Bogalusa, Louisiana) as part of a program investigating the early natural history of atherosclerosis. Black children had significantly higher mean levels of serum cholesterol than white children (170 mg/dl vs 162 mg/dl, P less than 0.0001). On the other hand, significantly lower levels of triglycerides were found in blacks than in whites (61 mg/dl vs 73 mg/dl, P less than 0.0001). Girls had higher levels of triglycerides than boys in both races (blacks, 64 mg/dl vs 59 mg/dl, P less than 0.001; whites, 77 mg/dl vs 69 mg/dl, P less than 0.001). The racial differences in serum cholesterol and triglyceride levels were even more apparent at the 95th percentile. The serum cholesterol level remained relatively constant in all children until ages 11 and 12 years, after which a slight reduction occurred. This reduction was more pronounced in boys than in girls. In contrast, a significant increase in the level of triglycerides with age was observed in all children except black girls, the increasing slope being most pronounced in white girls.

Adolescent↗
PubMed1976

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

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

Adolescent↗
PubMed1976

Studies of blood pressures in children, ages 5-14 years, in a total biracial community: the Bogalusa Heart Study.

Blood pressure, height, weight, maturation, triceps skinfold thickness, serum lipids, and hemoglobin were measured as risk factors for coronary artery disease in 3,524 children (93% of the eligible population) in Bogalusa, Louisiana. Nine blood pressures were taken on each child by trained observers with mercury sphygmomanometers (Baumanometer) and Physiometrics automatic recorders in a rigid randomized design in a relaxed atmosphere with other children present. The pressures observed were low compared to reported data. Black children had significantly higher blood pressures than white children. This difference, starting before age 10, was largest in the children in the upper five percent of the pressure ranks. Stepwise multiple regression analysis revealed that this racial differnce was significant when measured by an automatic recorder. Body size, expressed by height and by weight/height3 index, was a strong determinant of blood pressure level. Other positive determinants were blood hemoglobin and external maturation.

Adolescent↗
PubMed1976

Earlier onset of QRS in anterior precordial ECG leads: precision of time interval measurements.

Onset of QRS was compared between simultaneously recorded conventional ECG leads in 84 subjects with clinically normal hearts from a defined population sample. Mean onset of QRS was 6.4 msec earlier in lead V1 and 7.4 msec earlier in V2 than in lead II. These differences were statistically significant. The measuring system was adapted from drafting techniques and took into account variations in paper speed which occurred during recording. Interobserver differences equivalent to greater than 1 msec occurred in 3.9% of timeline measurements, but in in 38% of QRS onset measurements. The lower precision in measuring QRS onset may be attributed to baseline oscillations and to the relatively slow rate of voltage change at the onset of ventricular depolarization.

Adult↗
PubMedDate not supplied

Operational design and quality control in the CATCH multicenter Trial.

BACKGROUND: The Child and Adolescent Trial for Cardiovascular Health (CATCH) was the first multicenter school-based research study to employ the fundamentals of clinical trials including the standardized protocol and Manuals of Operation, a steering committee for study governance, a distributed data system, an extensive quality control system, and a Data and Safety Monitoring Board. METHOD: CATCH tested the effectiveness of changes in school lunches, physical education, smoking policy, curricula, and family activities. Ninety-six elementary schools in four states were randomized to intervention or control conditions. The baseline cohort comprised 5, 106 ethnically diverse third graders followed through fifth grade. RESULTS: The percentages of calories from fat and saturated fat were reduced significantly more in the intervention school lunches than among the controls. Significant increases in moderate to vigorous activity levels in existing physical education classes were made as well. Changes in self-reported dietary, physical activity, and psychosocial measures were significant. There were no significant differences in the physiological measures. Measurement error was generally low for all physiologic measures except skinfolds, indicating a high level of reliability. Across all sites, the coefficients of variation for lipids, height, and weight were less than 3%, whereas for skinfolds, they were considerably higher, ranging from 6 to 8%. Intraclass correlations for lipid studies were also uniformly high at 0.99. Interobserver agreement scores for SOFIT were greater than 90% for 9 of the 11 activities observed. Data entry error rates were low with less than five errors per 1,000 fields for all forms. CONCLUSIONS: The CATCH results provided more scientific evidence on the importance of schools in the population approach to health promotion. Many of the strategies used in this complex multicenter trial in the areas of design and analysis, measurement, training, data management, and quality control protocols might be appropriate for adoption in other studies.

Adolescent↗
PubMedDate not supplied

Cardiovascular risk factors among children after a 2 1/2-year intervention-The CATCH Study.

BACKGROUND: Cardiovascular risk factors and related behaviors begin during youth. METHODS: As part of the Child and Adolescent Trial for Cardiovascular Health, 4,019 children from four states and representing multiple ethnic groups were measured for selected risk factors both at baseline and after 2(1/2) years of intervention. Common protocols were used for both examinations at the four sites. RESULTS: Overall, changes in obesity, blood pressure, and serum lipids in the intervention group, compared with the control group, were not statistically significant. Total cholesterol, the primary physiologic outcome measure, decreased by 1.3 mg/dl over time in the intervention group and by 0.9 mg/dl (P > 0.05) in the control group. Different risk factor patterns for boys and girls and among three ethnic groups were noted. CONCLUSIONS: Although the school-based program effected significant institutional changes in food service and physical education class and although the children made significant changes in eating and physical activity behaviors, these did not translate to significant changes in risk factors at these ages. These behavioral changes, however, if sustained into adulthood, have the potential to influence cardiovascular risk reduction.

Adolescent↗
PubMedDate not supplied

Biochemical and anthropometric determinants of serum beta- and pre-beta-lipoproteins in children. Bogalusa Heart Study.

A special in-depth substudy was conducted on 388 children from a total biracial (black-white) population, who were stratified on levels of serum beta- and pre-beta-lipoprotein cholesterol to explore factors associated with lipoprotein levels in childhood. Biochemical parameters on venous blood samples were obtained both on fasting subjects and after an abbreviated glucose tolerance test, along with selected anthropometric measures like height, weight, and skinfolds. Biochemical and anthropometric relationships were minimal for children with elevated beta-lipoprotein cholesterol and low pre-beta-lipoprotein cholesterol. On the other hand, children with higher levels of pre-beta-lipoprotein cholesterol, with or without elevated beta-lipoprotein cholesterol, showed associations with fatness and slightly higher levels of glucose and insulin, with other biochemical parameters considered within normal levels. These differences noted among free-living children with different levels of serum lipoproteins provide clues to mechanisms involved in the early natural history of coronary artery disease.

Adolescent↗
PubMedDate not supplied

Clustering of anthropometric parameters, glucose tolerance, and serum lipids in children with high and low beta- and pre-beta-lipoproteins. Bogalusa Heart Study.

Children initially aged 21/2 to 14 years living in Bogalusa, Louisiana (n = 2530) were examined twice, 3 years apart, for fasting serum pre-beta- and beta-lipoprotein cholesterol (beta-LPC) levels. Based on averages of these levels, the children were ranked for pre-beta- and beta-LPC in combinations of extreme quintiles (low-low, high-high) or quartiles (low-high, high-low), n = 388, and were reexamined for serum lipids, lipoprotein cholesterol, glucose tolerance, and anthropometry. Skinfolds were thicker in whites than in blacks except for subscapular skinfold. Children in the high-high stratum were heavier and more obese. The postglucose insulin level was positively correlated with fasting serum triglycerides and pre-beta-LPC. Compared with other strata, high-high strata showed more clustering among half-hour and 1-hour plasma insulin, serum triglycerides and pre-beta-LPC, and trunk skinfolds. We conclude that racial differences in lipid and carbohydrate metabolism occur in all four strata, and that a strong clustering occurs more in the high-high stratum, which may, in part, explain the coincidence of several high cardiovascular risk factor levels observed in the same children. These observations document in free-living children changes of obesity, plasma glucose, and insulin metabolism related to serum lipoproteins that are involved in the early natural history of atherosclerosis.

Adipose Tissue↗
PubMedDate not supplied

Divergent levels of high density lipoprotein cholesterol and apolipoprotein A-I in children. The Bogalusa Heart Study.

Clinical studies indicate that levels of apolipoprotein A-I (apo A-I), the major protein moiety of the high density lipoprotein (HDL) particle, may provide more information concerning the risk of future cardiovascular disease than do levels of HDL cholesterol (HDL-C). Therefore, the relationship of HDL-C to apo A-I levels was examined in a biracial sample of 2849 5- to 17-year-olds. The mean HDL-C to apo A-I ratio, a measure of HDL composition, was 0.42. However, marked interindividual variation was found: HDL-C/apo A-I levels varied from 0.27 (10th percentile) to 0.57 (90th percentile). Furthermore, only 26% of the variation in HDL-C levels was explained by concomitant variation in apo A-I. Increasing levels of triglyceride (and very low density lipoprotein cholesterol) were related to decreases in both the HDL-C/apo A-I ratio and the magnitude of the correlation between HDL-C and apo A-I. Low density lipoprotein cholesterol, race, and age were also related to the HDL-C/apo A-I ratio, but influenced HDL composition less strongly than did triglyceride levels. These observations may be explained by the bidirectional transfer of cholesteryl esters and triglycerides between HDL and triglyceride-rich lipoproteins. The current study documents the influence of triglyceride levels on HDL composition in a general population of children and adolescents, and emphasizes the interrelationships between the various lipid and lipoprotein fractions.

Age Factors↗