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Biomedical subjects

L S Webber

Publications and source records attributed to L S Webber.

207 records · Page 12Linked to original sources
PubMedDate not supplied

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

Levels of high density lipoprotein cholesterol (HDL-C) and apolipoprotein A-I (apo A-I) may provide independent information concerning cardiovascular disease risk. Therefore, possible correlates of HDL-C and apo A-I levels were studied in 2827 5- to 17-year-olds from a biracial community, and the possible differences in these relationships were assessed. The characteristics examined included sexual maturation, plasma levels of glucose and insulin, obesity, reported oral contraceptive use, alcohol consumption, and cigarette smoking. In addition, levels of endogenous sex hormones (testosterone, estrogen, and progesterone) were measured in 515 adolescent males. HDL-C and apo A-I levels showed different (p less than 0.001) relationships with both obesity and oral contraceptive use. Increases in subscapular skinfold thickness corresponded more closely to decreases in HDL-C, rather than apo A-I, levels; the relationship with HDL-C was probably mediated by triglyceride levels. In contrast, oral contraceptive use was associated with increases in mean levels of apo A-I (8 mg/dl, whites; 16 mg/dl, blacks), but with only very small changes in HDL-C. (High-estrogen oral contraceptives were related most closely to increases in levels of both HDL-C and apo A-I). Levels of both HDL-C and apo A-I were similarly related to sexual maturation and levels of testosterone (negatively in boys), cigarette smoking (negatively), and alcohol intake (positively). Since levels of apo A-I independently of HDL-C may indicate an increased risk of cardiovascular disease, characteristics related to apo A-I levels should be further examined.

Adolescent↗
PubMedDate not supplied

Dietary factors relate to cardiovascular risk factors in early life. Bogalusa Heart Study.

Relationships between diet and cardiovascular disease risk factors were studied in a cohort of infants in Bogalusa, Louisiana. The 24-hour dietary recalls and cardiovascular measurements were obtained on each child at age 6 months, yearly through age 4, and again at age 7 (cardiovascular measurements only). At ages 4 and 7, children with persistently high intakes of dietary cholesterol (three or more measurements in the upper tertile) had levels of serum total cholesterol approximately 14 mg/dl higher than children whose intakes of cholesterol were not persistently high. Children in the upper tertile for dietary cholesterol had levels of low density lipoprotein cholesterol (15 mg/dl at age 4 and 18 mg/dl at age 7) higher than children in the lower tertile for dietary cholesterol. Children with high intakes of animal fat were 2 to 6 kg heavier (p less than 0.05) than those with lower intakes. Changes in dietary cholesterol correlated significantly with changes in serum total cholesterol (r = 0.42) and low density lipoprotein cholesterol (r = 0.50) from 6 months to 4 years of age. Changes in subscapular skinfold measurements correlated significantly with changes in intake of total protein (r = 0.31), total fat (r = 0.25), starch (r = 0.31), and energy (r = 0.39) from ages 6 months to 4 years. Results indicate that tracking of dietary components and their relationships with cardiovascular disease risk factors can be detected at an early age. These findings may well be the groundwork for later studies of obesity and the early onset of hyperlipoproteinemia.

Cardiovascular Diseases↗
PubMedDate not supplied

Relation of cholesterol to apolipoprotein B in low density lipoproteins of children. The Bogalusa Heart Study.

Cholesterol and apolipoprotein (apo) B contents and their relationship within serum low density lipoprotein (LDL) were examined in 2018 children, ages 8 to 17 years, from a biracial community. The levels of LDL cholesterol and LDL apo B showed significant race-related differences (blacks greater than whites) in both boys and girls and gender-related differences (girls greater than boys) in white children. These LDL measures associated inversely and significantly with both age and Tanner stage, more so in boys than in girls. The black-white differences in LDL measures persisted after adjusting for the covariates (sexual maturation, age, adiposity, oral contraceptive use, cigarette smoking, and alcohol use). The distribution of LDL cholesterol for a given range of LDL apo B varied considerably, despite a strong correlation (r = 0.91) between these variables, indicating that measuring LDL cholesterol alone does not accurately reflect LDL concentration. The ratio of cholesterol to apo B in LDL ranged from 1.01 (5th percentile) to 1.42 (95th percentile) among the four race-gender groups, suggesting marked interindividual variation in composition. That this ratio was significantly elevated in black children indicates the occurrence of relatively larger, less dense, and cholesterol-enriched LDL particles in blacks. Significant independent associations were noted between LDL cholesterol/apo B ratios and the levels of serum total cholesterol (positive) and triglycerides (negative), suggesting the influence of pool size of different lipoproteins on LDL composition. These observations may help identify a subgroup of children with apo B-enriched LDL particles who are potentially at risk for coronary artery disease.

Adolescent↗
PubMedDate not supplied

Racial contrasts in cardiovascular response tests for children from a total community.

Cardiovascular risk factors in childhood were assessed by re-examining a random sample of 278 children stratified by diastolic blood pressure (BP), obtained from 3524 children aged 7-15 years in an entire geographic biracial community (Bogalusa). Re-examination included plasma renin and serum electrolytes, 24-hour urine electrolytes, heart rates, and BP at rest and in response to standardized physical stresses (orthostatic, isometric handgrip, and cold pressor tests). The BP responses in these tests were not increased in the high BP strata, which argues against a prevailing labile phase in early essential hypertension. Black children tended toward larger BP responses than whites. In black boys of the high BP stratum (n = 25), systolic supine or stressed BP were higher than for other race-sex groups; these pressures were associated negatively with plasma renin activity, which was low. White children in the high BP strata had increased heart rates, possibly indicating hyperkinetic circulation. These findings indicate that multiple mechanisms operate to contol BP at different intensities for black and white children.

Adolescent↗
PubMedDate not supplied

Comparison of two automatic blood pressure recorders and the mercury sphygomomanometer.

The Physiometrics automatic blood pressure recorder was compared with the mercury sphygmomanometer in 2200 children aged 5-14 years, each reexamined after 3 and 5 years; the Physiometrics recorder produced higher intrachild correlations. In trials we could transfer what were essentially Physiometrics readings into levels similar to mercury sphygmomanometric readings by filtering out the infrasonic frequency band. The Physiometrics USM-105 was compared with its successor, the Physiometrics SR-2, on 378 children aged 10-17 years. The SR-2 measured lower than the USM-105: 4.1 mm Hg systolic and 8.5 mm Hg diastolic; differences were larger in the younger children. Both in mean levels and correlations, SR-2 readings were closer to the mercury sphygmomanometer's than were USM-105 readings, except or diastolic SR-2 readings, which were farther below the mercury sphygomomanometer 4th-phase readings than the USM-105. However, the SR-2 readings are likely closer to the true diastolic pressure in children 13 years and older, although we did not measure pressures intraarterially. Disc readings for systolic pressures showed coefficients of correlation averaging 0.96 among (n = 168) and 0.98 within (n = 40) readers for both models, but diastolic readings showed marked improvement form USM-105 (0.73, 0.81) to SR-2 (0.91, 0.97). In many of the parameters observed, SR-2 constitutes an improvement over USM-105. Automatic recorders offer certain advantages for measuring blood pressure in large-scale epidemiologic studies.

Adolescent↗
PubMedDate not supplied

A model of intervention for prevention of early essential hypertension in the 1980s.

The onset of essential hypertension early in life is indicated by the high tracking of blood pressure during adolescence; intervention in adults with mild hypertension has been found successful. How, then, can high blood pressure levels in children be modified to prevent early hypertensive cardiovascular disease in adulthood? In an entire biracial town (population 9000) we surveyed 1604 (89%) of all children aged 8--18 years for blood pressure and reexamined those in the upper decile of mean blood pressure (for each race, sex, and height) on three additional occasions. On each examination nine blood pressures were taken by trained observers. All children consistently in the top decile were randomly allocated into either a treatment (n = 50) or comparison (n = 50) group. These two groups and an additional midrange blood pressure comparison group (n = 50) were followed regularly using school facilities including community and school programs. Treatment consisted of 1) dietary guidance; 2) modifications of school lunches and snacks with healthy substitutes; 3) parental involvement; 4) a low dose diuretic and beta-antagonist given by usual standards. All study groups were monitored for blood pressure in a blind manner. In 6 months of observation, blood pressure in the treatment group remained 5 and 3 mm Hg (systolic and diastolic) less than controls (p less than 0.001 and p less than 0.01). An orchestrated community-wide attack on early-stage hypertension is feasible and seems to offer exciting potential for prevention of early hypertensive disease.

Adolescent↗
PubMedDate not supplied

Time course study of blood pressure in children over a three-year period. Bogalusa Heart Study.

Indirect blood pressure (BP) was measured by mercury sphygmomanometer on 3524 children, ages 5-14 years, representative of a defined geographic population. Year 1 to Year 4 correlations ranged from 0.52 to 0.63 systolic blood pressure (SBP) and from 0.23 to 0.45 diastolic 4th phase blood pressure (DBP4). Some 55% of those originally in the upper decile remained in the uppermost two deciles 3 years later. All children ages 5, 8, 11, and 14 years were reexamined annually, and the mean year-to-year standard deviation (SD) within the child was computed to be 5.5 mm Hg SBP and 5.9 mm Hg DBP. After 3 years, for all available children (n = 2601) the age-specific cross-sectional SD was found to be 8.7-9.7 mm Hg SBP and 7.6-8.0 mm Hg DBP. These data enabled us to quantify the regression to the mean due to within-child variation for the uppermost and the lowest decile BP, using the Gardner-Heady model. These children had an average BP at examination that differed from the expected level (adjusting for regression to the mean due to within-child variation) by 1 mm Hg SBP and DBP. Quantification of the degree to which children's BP "tracks" is important for early diagnosis and intervention in high BP.

Anthropometry↗
PubMedDate not supplied

Hemoglobin levels and dietary iron in pubescent children in a biracial community.

Although differences in hemoglobin levels between blacks and whites may be due in part to genetic influences, low hemoglobin levels in black girls of childbearing age may nevertheless constitute a health hazard. To study this problem, hemoglobin levels were examined in children of a biracial community not only before but also during and after puberty and menarche. At the same time, 24-hour dietary recalls of a representative group of 13-year-olds in the same population were examined with respect to the intake of iron and nutrients influencing iron absorption. In black girls, hemoglobin levels dropped after menarche, accompanied by a diet marginal in iron and in iron-absorption-promoting nutrients. Questions as to hemoglobin levels compatible with optimum health remain, and racial differences and genetic influences on levels should not be an excuse for failure to address this problem. More investigational studies are also needed to observe responses to an optimum dietary iron intake.

Adolescent↗