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Biomedical subjects

J A Morrison

Publications and source records attributed to J A Morrison.

At least 19 recordsLinked to original sources
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

Emotion-induced eating and sucrose intake in children: the NHLBI Growth and Health Study.

OBJECTIVE: Emotion-induced eating has been implicated as a risk factor for the development of obesity, yet no research has been done on emotion-induced eating in children. The National Heart, Lung, and Blood Institute Growth and Health Study (NGHS), a multicenter collaborative study of risk factors for obesity, developed an instrument for measuring emotion-induced eating in children and tested hypotheses regarding the association of emotion-induced eating with food intake and adiposity in preadolescent children. METHOD: Subjects were 1,213 black girls and 1,166 white girls who were 9 and 10 at study entry. Baseline data were utilized in this report. Girls were assessed by trained female health examiners who recorded height, weight, and indices of sexual maturation. Girls kept a 3-day food diary. Dietary data were coded and analyzed for total caloric and macro nutrient intake. A measure of emotion-induced eating was derived from seven questions about eating in response to emotions (Cronbach's alpha = .78). RESULTS: Black girls had significantly higher emotion-induced eating scores than white girls (10.8 vs. 9.7, p < .0001). For white girls, but not for black girls, emotion-induced eating was associated with increased intake of sucrose. In both races, a modest inverse association was found between body mass index and emotion-induced eating. DISCUSSION: Prospective studies are needed to explore further the role of emotion-induced eating and food intake and the role of emotion-induced eating in the development of obesity.

Affect↗
PubMed1998

Sex hormones and lipoproteins in adolescent male offspring of parents with premature coronary heart disease and a control group.

OBJECTIVE: To compare pubertal maturation, sex steroid hormones, and lipoproteins and their interrelationships in male offspring of parents with premature coronary heart disease (cases) and a control group. DESIGN: This was a cross-sectional comparison of cases and members of a control group 10 to 15 years of age. SUBJECTS AND METHODS: Offspring were recruited from patient lists of area physicians. Members of the control group were recruited from area schools. Body mass (kg/m2), serum lipids, lipoproteins, apolipoproteins, estradiol, and free testosterone were measured. RESULTS: Differences in age were not significant, but offspring were taller, heavier, and more mature. Offspring had higher total and low density lipoprotein cholesterol. Offspring had lower estradiol levels in early puberty but higher levels in late puberty. With family history and body mass in the regression models for lipid parameters, free testosterone was a significant explanatory factor for total cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein, and estradiol was a significant predictor for apolipoprotein B. The percent of the variance in the lipid parameters explained by testosterone and estradiol was small. CONCLUSION: Sex hormone concentrations appear to be modest but significant predictors of lipoprotein and apolipoprotein concentrations in offspring and a control group in cross-sectional analysis. After controlling for pubertal maturation, hormone and lipid concentrations differed in offspring and the control group.

Adolescent↗
PubMed1998

The conjoint trait of low high-density lipoprotein cholesterol and high triglycerides in adolescent black and white males.

To evaluate the interrelationships among body composition, blood pressure, and lipid phenotypes in adolescent black and white boys, we assessed racial distributions of lipids, blood pressure, and obesity and their joint occurrence in black and white boys aged 10 to 15 years. Subjects were recruited from Cincinnati (OH) schools. Because the differences in high-density lipoprotein cholesterol (HDL-C) and triglycerides (TGs) are the most profound coronary heart disease (CHD) risk factor differences between black and white males, we assigned subjects to one of four low-HDL-C and high-TG categories (normal and increased risk) using the age/race-specific 25th (HDL-C) and 75th (TG) percentiles. We then assessed racial distributions of lipids, blood pressure, and obesity by these phenotypes. Age differences between the black and white participants were significant, with the former about 3 months younger (P=.03), but black boys were more mature and were significantly taller and heavier and had a greater body mass index ([BMI] weight in kilograms divided by height in centimeters squared). Differences in the sum of the triceps, subscapular, and suprailiac skinfolds were not significant. Blacks had significantly higher HDL-C, lower TG, and higher diastolic blood pressure (DBP), but differences in systolic blood pressure (SBP) were not significant. In both racial groups, the body composition measures were significantly correlated with HDL-C, TG, and blood pressure levels; the correlations between HDL-C and both weight and BMI were significantly stronger in white boys. The proportion of boys of each race with low HDL-C and high TG was similar by design. In both racial groups, subjects with the conjoint trait had a significantly greater BMI, triceps skinfold, and sum of skinfolds than subjects in the other phenotypic groups. For white boys, participants with the conjoint trait had the highest SBP and DBP; differences in SBP were significant for comparisons to the normal- and high-TG group alone, and differences in DBP were significant for the comparison between normal and low HDL-C alone. For black boys, subjects with both normal HDL-C and TG had significantly lower SBP than boys with either the conjoint trait or high TG alone; none of the group differences in DBP were significant. Black had significantly less dense LDL (more LDL-C per apolipoprotein [apo] B). In each racial group, boys with the conjoint trait had the most dense LDL, significantly more dense than in any of the other phenotypes in black boys and significantly more dense than in boys with low HDL-C alone and normal boys in the white group. In both racial groups, the occurrence of no risk factors (>75th percentile TG, BMI, SBP, and DBP or <25th percentile HDL-C) and three or more risk factors was greater than expected by chance alone, and the occurrence of exactly one risk factor and two factors was less. When examined by phenotypic groups within race, boys in each racial group with the normal phenotype had a greater than expected percentage with no risk factors, and white boys with the conjoint trait were more likely to have a marked increase in multiple risk factors. Possible mechanisms for this clustering of risk factors and for the racial differences in the patterns are discussed.

Adolescent↗
PubMed1998

Longitudinal correlates of change in blood pressure in adolescent girls.

The objective of this study was to assess the longitudinal changes in blood pressure in black and white adolescent girls and evaluate potential determinants of changes in blood pressure, including sexual maturation and body size. A total of 1213 black and 1166 white girls, ages 9 or 10 years at study entry, were followed up through age 14 with annual measurements of height, weight, skinfold thickness, stage of sexual maturation, systolic and diastolic blood pressures, and other cardiovascular risk factors. Average blood pressures in black girls were generally 1 to 2 mm Hg higher than in white girls of similar age over the course of the study. Age, race, stage of sexual maturation, height, and body mass index (kg/m2) were all significant univariate predictors of systolic and diastolic blood pressures in longitudinal regression analyses. Black girls had a significantly smaller increase in blood pressure for a given increase in body mass index compared with white girls. The predicted increases in blood pressure per unit increase in body mass index (mm Hg per kg/m2) were as follows: systolic, 0.65+/-0.04 in whites and 0.52+/-0.04 in blacks (P<.001); diastolic fourth Korotkoff phase, 0.31+/-0.04 in whites and 0.15+/-0.03 in blacks (P<.001); and diastolic fifth Korotkoff phase, 0.31+/-0.05 in whites and 0.16+/-0.04 in blacks (P<.001). Understanding of the determinants of the racial differences in blood pressure could provide the rationale for future interventions to reduce the excess cardiovascular mortality in black compared with white women.

Adolescent↗
PubMed1997

Lipoprotein and apolipoprotein differences in black and white girls. The National Heart, Lung, and Blood Institute Growth and Health Study.

OBJECTIVE: To define racial differences in lipoprotein and apolipoprotein levels in girls aged 9 to 10 years. DESIGN: Baseline analysis of a prospective cohort study. SETTING: Three clinical sites. SUBJECTS: A total of 1871 black and white girls, aged 9 to 10 years, with complete maturation data (pubic hair and areolar development and menarche) and an 8-hour fast before blood draw. MAIN OUTCOME MEASURES: Anthropometric measures and serum lipid, lipoprotein, and apolipoprotein levels. RESULTS: All analyses were adjusted for maturational differences between blacks and whites (areolar or pubic hair development and menarche). The mean body mass index was marginally higher in black girls than in white girls (18.9 vs 18.3 kg/m2; P = .002), while the sum of skinfolds (34.5 vs 34.8 mm; P = .77) was equivalent. However, both body mass measures were skewed higher at the upper percentiles in black girls. The low-density lipoprotein cholesterol level was similar between black and white girls. Mean triglyceride values were higher in white girls than in black girls (0.92 vs 0.79 mmol/L [81 vs 70 mg/dL]; P < .001); however, these differences were most pronounced in the upper percentiles. Conversely, mean high-density lipoprotein cholesterol and apolipoprotein A-I levels were higher in black girls than in white girls (1.44 vs 1.37 mmol/L [56 vs 39 mg/dL] and 147 vs 138 mg/dL, respectively; both P < .001); and again the differences were most evident at the upper end of the distributions. CONCLUSIONS: Racial differences in the mean levels of triglycerides, high-density lipoprotein cholesterol, and body mass in girls in the National Heart, Lung, and Blood Institute Growth and Health Study (NGHS) at age 9 to 10 years were predominantly the result of differences observed at the upper end of the distributions. The reported black-white differences for mean high-density and low-density lipoprotein cholesterol and triglyceride levels in adult women are comparable to NGHS results. Distributional characteristics of these risk factors as well as trends in lipids, lipoproteins, and apolipoproteins, will be evaluated in an ongoing longitudinal assessment that covers the full maturational period.

Apolipoproteins↗
PubMed1997

Predictors of severity of acne vulgaris in young adolescent girls: results of a five-year longitudinal study.

OBJECTIVES: The objectives of this study were to determine which factors in early pubertal girls might be predictive of later, severe facial acne. STUDY DESIGN: The study was a 5-year longitudinal cohort study, with yearly visits from 1987 through 1991, in a volunteer sample of 439 black and 432 white fourth- and fifth-grade girls with consent from their legal guardians. The subjects were recruited from public and parochial schools in Cincinnati, Ohio. The degree of facial acne was classified annually as mild, moderate, or severe. Blood samples were obtained at the first, third, and fifth years of the study. Using the acne status during the fifth year of the study as the outcome variable, we determined the contributions from the prior acne status and the serum levels of dehydroepiandrosterone sulfate (DHEAS), testosterone, free testosterone (FT), estradiol (E2), progesterone, and testosterone-estrogen binding globulin (TEBG) and compared the results at various ages and at times before and after menarche. RESULTS: No racial differences in acne or hormone levels were found. There was a progressive increase in the number of acne lesions with age and maturation. The girls exhibited many more comedonal than inflammatory acne lesions, regardless of age. The girls in whom severe acne developed by the fifth year of the study had significantly more comedones and inflammatory lesions than girls with mild or moderate acne, as early as age 10 years, approximately 2 h years before menarche, a time when their degree of acne was mild. Girls with mild comedonal acne had significantly later onset of menarche (12.5 compared with 12.2 years) than girls with severe comedonal acne. Girls in whom severe comedonal acne developed had significantly higher levels of serum DHEAS and, in a longitudinal analysis, somewhat higher levels of testosterone and FT in comparison with girls who had mild or moderate comedonal acne. Serum E2, testosterone/E2, progesterone, and TEBG values were no different in girls with severe compared with mild or moderate comedonal acne. CONCLUSIONS: The early development of comedonal acne may be one of the best predictors of later, more severe disease. The adrenal hormone DHEAS appears to play an important role in the initiation of acne. DHEAS, testosterone, and FT are associated with the perpetuation of severe comedonal acne. Early recognition of young girls at risk of having severe comedonal acne may enable the clinician to intervene and thus prevent unwanted sequelae.

Acne Vulgaris↗
PubMed1997

The utility of body mass index as a measure of body fatness in children and adolescents: differences by race and gender.

OBJECTIVE: To evaluate whether body mass index (BMI) is a representative equivalent measure of body fatness independent of age, race, gender, sexual maturation, and distribution of fat in children and adolescents. STUDY DESIGN: Cross-sectional study of 192 healthy subjects (100 boys and 92 girls, 103 white and 89 black) age 7 to 17 years. Methods. Height and weight were measured in the standard fashion, and BMI (kg/m) was calculated from these values. Fat mass and percent body fat were determined using dual-energy x-ray absorptiometry. Sexual maturation was evaluated by physical assessment. Distribution of fat was determined by the waist:hip ratio. RESULTS: There were no significant differences by gender and ethnic group for any of the demographic or anthropometric variables, except waist:hip ratio, which was higher in white compared with black boys. BMI was significantly and positively correlated with age, stage of maturation, and all of the anthropometric variables in each race-sex group. The correlation of maturation stage with BMI was stronger than the correlation between age and BMI. A multiple regression analysis showed that BMI, gender, race, sexual maturation, and distribution of fat were all significant independent correlates of the percent body fat (multiple R = .77). The percent body fat-BMI relationship was dependent on the stage of sexual maturation, gender (for an equivalent BMI, girls have greater amounts of body fat than boys), race (for equivalent BMI, whites have higher body fat than blacks), and waist:hip ratio (for equivalent BMI, those with central obesity have greater body fatness than those with peripheral obesity). CONCLUSION: BMI is not an equivalent measure of the percent body fat for each race-sex group. When BMI is used as a measure of body fatness in a research or clinical setting, particularly when comparisons are made across race and gender, it may be important to consider the maturation stage, race, gender, and distribution of body fat in the interpretation of the results.

Absorptiometry, Photon↗
PubMed1997

Sociodemographic factors and obesity in preadolescent black and white girls: NHLBI's Growth and Health Study.

The association of sociodemographic and family composition data with obesity was studied in 1213 black and 1166 white girls, ages 9 and 10, enrolled in the National Heart, Lung, and Blood Institute's Growth and Health Study. Obesity was defined as body mass index at or greater than age- and sex-specific 85th percentile as outlined in the Second National Health and Nutrition Examination Survey. The prevalence of obesity was higher for pubertal girls than for prepubertal girls and for girls with older mothers/female guardians. As odds ratio of 1.14 was observed for each 5-year increase in maternal age. Obesity was less common for girls with more siblings; the odds for obesity decreased by 14% for each additional sibling in the household. In blacks, the prevalence of obesity was not related to parental employment or to parental education. In whites, the odds of obesity were higher for girls with no employed parent/guardian in the household and for girls with parents or guardians with lower levels of educational attainment. Examining the associations between sociodemographic factors and risk of childhood obesity provides important clues for understanding racial differences in obesity, a major risk factor for coronary heart disease.

Black or African American↗
PubMed1996

Differential classification of blood pressure by fourth and fifth Korotkoff phases in school-aged girls. The National Heart, Lung, and Blood Institute Growth and Health Study.

The use of the onset of the fourth (K4) or fifth (K5) Korotkoff phase to determine diastolic blood pressure in children has been controversial; most recently, the Second Task Force recommended the use of K4 for children up to age 13 years and K5 for children age 13 and above. We performed a cross-sectional analysis of 1,155 nine-year old (53% white and 47% black) and 1,224 ten-year old girls (45% white and 55% black) in the National Heart, Lung, and Blood Institute Growth and Health Study (NGHS). The mean blood pressures for the first, fourth, and fifth Korotkoff phases were 100.1 (+/- 8.9) mm Hg, 66.6 (+/- 9.8) mm Hg, and 56.8 (+/- 11.8) mm Hg for nine-year-olds and 102.8 (+/- 9.0) mm Hg, 68.1 (+/- 10.1) mm Hg, and 58.1 (+/- 11.9) mm Hg for ten-year-olds. The mean difference between K4 and K5 was 9.9 (+/- 6.4) mm Hg. The correlation between K1 and K4 was 0.45, between K1 and K5 was 0.34, and between K4 and K5 was 0.84. Elevation of blood pressure was defined at or above the 95th percentile based on the NGHS distribution for K1, K4, or K5; the relative risk of having an elevated K1 was 10.1 if K4 was elevated and 5.9 if K5 was elevated. Of the 159 subjects potentially classified with elevated diastolic pressure, 95 subjects (60%) would be classified differently depending on whether K4 or K5 was used to define elevated diastolic blood pressure. The choice of the onset of the fourth or fifth Korotkoff phase for determining diastolic blood pressure in children may have important implications for which individuals are classified as having hypertension.

Blood Pressure↗
PubMed1996

Determinants of resting energy expenditure in young black girls and young white girls.

OBJECTIVE: To identify determinants of resting energy expenditure (REE) in black girls and white girls and to evaluate racial differences in REE. STUDY DESIGN: Cross-sectional study of 98 girls (47 black and 51 white girls), ages 6 to 16 years. METHODS: Determinations of lean body mass, fat mass, and bone mass were made by dual-energy x-ray absorptiometry. Measurements of REE were made with the DeltaTrac metabolic monitor. Subjects fasted at least 3 hours before testing, had rested 30 minutes before the test, and had not engaged in strenuous activity for the previous 12 hours. Pubertal maturation was assessed with a three-stage scoring method: (1) prepubertal, (2) pubertal, but premenarcheal, and (3) postmenarcheal. RESULTS: There were no significant differences in height, weight, lean body mass, or fat mass between the black and white subjects. Racial differences in total REE were also not significant, but REE standardized by weight was significantly greater in white girls (40.3 kcal/day) compared with black girls (35.5 kcal/day) (p = 0.001). Resting energy expenditure was positively and significantly correlated with all measures of body composition. Multiple regression analysis identified lean body mass, sexual maturation, and race as significant main effects. After controlling for lean body mass and maturation, black girls had significantly lower REE. The race-maturation interaction was of borderline significance (p = 0.09); prepubertal black girls had significantly lower REE (1156 kcal/day) than prepubertal white girls (1399 kcal/day), but racial differences in stages 2 and 3 were not statistically significant. CONCLUSION: Lean body mass, maturation, and race are significant determinants of REE. Resting energy expenditure is significantly lower in black than white girls in the prepubertal stage. The cause of this racial difference in REE is not known; it is not explained by differences in anthropometric variables. Racial differences in REE could explain in part the earlier onset of puberty in black girls compared with white girls and could be a factor in the difference in obesity in black and white women.

Absorptiometry, Photon↗
PubMed1996

Sexual maturation and racial differences in blood pressure in girls: the National Heart, Lung, and Blood Institute Growth and Health Study.

OBJECTIVE: To evaluate racial differences in blood pressure in girls aged 9 to 10 years in the National Heart, Lung, and Blood Institute Growth and Health Study (NGHS) and to evaluate the extent to which racial differences in blood pressure are explained by other factors, including sexual maturation and body size. METHODS: The NGHS enrolled 539 black and 616 white girls aged 9 years, and 674 black and 550 white girls aged 10 years. Racial differences in blood pressure were examined. Relationships of stage of sexual maturation, height, and skinfold thickness with systolic and diastolic blood pressure were evaluated by multiple regression analysis. RESULTS: The black girls had significantly higher systolic (102.0 +/- 8.90 vs 100.5 +/- 9.42 mm Hg, p <0.001) and diastolic (58.0 +/- 12.0 vs 56.5 +/- 12.51 mm Hg, p <0.01) blood pressures than the white girls. The black girls were also more advanced in sexual maturation and were taller (142.9 +/- 7.94 vs 139.6 +/- 7.05, p <0.001) and heavier (39.6 +/- 11.24 vs 35.3 +/- 8.73 kg, p <0.001) than the white girls. Both systolic and diastolic blood pressure were significantly correlated with level of maturation, height, weight, and sum of skinfolds. Stage of maturation was found to account for the difference in blood pressure between black girls and white girls. In a multiple regression analysis, controlling for height (for diastolic blood pressure) and for both height and sum of skinfolds (for systolic blood pressure) eliminated the effects of race and stage of maturation on blood pressure. CONCLUSION: Racial differences in blood pressure were observed for 9- and 10-year-old girls and are explained by the fact that black girls were more mature than white girls. The effect of sexual maturation on blood pressure appears to operate through height and body fat. The effect of obesity may be more important for systolic than for diastolic blood pressure. Continuation of racial differences in blood pressure may result in a higher prevalence of hypertension for black women.

Adipose Tissue↗
PubMed1996

Obesity and high-density lipoprotein cholesterol in black and white 9- and 10-year-old girls: The National Heart, Lung, and Blood Institute Growth and Health Study.

It has been hypothesized that the role of obesity in the pathogenesis of coronary heart disease (CHD) may be mediated in part through its inverse relationship with high-density lipoprotein cholesterol (HDL-C). Obesity is inversely correlated with HDL-C, and HDL-C has been shown to be protective against CHD. Defining obesity as excess weight due to excess fat, the purpose of this analysis was to determine whether the effects of obesity are due to increased weight or to increased adiposity. Using baseline lipid and anthropometric data from the National Heart, Lung, and Blood Institute Growth and Health Study, cross-sectional associations among body mass, adiposity, HDL-C, and related lipid parameters (apolipoprotein [apo] AI and triglycerides [TGs]) were assessed in 821 white and 763 black 9- and 10-year-old girls, using multivariate linear regression models. Equations predicting HDL-C, apo AI, and TGs from age, race, race, sexual maturation stage, adiposity (sum of truncal--subscapular and suprailiac--skinfolds), and ponderosity (a ratio of weight to height) revealed that adiposity, not ponderosity, was the significant body composition variable to explain the variability of each of the lipids assessed. The amount of variance explained in each of the models was small (R2 <or= .10). When apo AI and TGs were added to the HDL-C model, R2 increased to 0.44 and race differences were no longer significant. These finding suggest that adiposity, not ponderosity, explains the effects of obesity on HDL-C, the effects are mediated through apo AI and TGs, and that black-white differences in HDL-C are a result of apo AI and TG-metabolic differences between the races.

Anthropometry↗
PubMed1996

Race, socioeconomic status, and obesity in 9- to 10-year-old girls: the NHLBI Growth and Health Study.

The purpose of this investigation was to determine whether measures of socioeconomic status (SES) are inversely associated with obesity in 9- to 10-year-old black and white girls and their parents. Subjects were participants in the Growth and Health Study (NGHS) of the National Heart, Lung, and Blood Institute. Extensive SES, anthropometric, and dietary data were collected at baseline on 2379 NGHS participants. The prevalence of obesity was examined in the NGHS girls and parents in relation to SES and selected environmental factors. Less obesity was observed at higher levels of household income and parental education in white girls but not in black girls. Among the mothers of the NGHS participants who were seen, lower prevalence of obesity was observed with higher levels of income and education for white mothers, but no consistent patterns were seen in black mothers. Univariate logistic models indicated that the prevalence of obesity was significantly and inversely associated with parental income and education and number of parents in the household in white girls whereas caloric intake and TV viewing were significantly and positively associated with obesity. Among black girls, only TV viewing was significantly and positively associated with the prevalence of obesity. Multivariate logistic regression models revealed that lower parental educational attainment, one-parent household, and increased caloric intake were significantly associated with the prevalence of obesity in white girls; for black girls, only increased hours of TV viewing were significant in these models. It is concluded that socioeconomic status, as measured by education and income, was related to the prevalence of obesity in girls, with racial variation in these associations. A lower prevalence of obesity was seen at higher levels of socioeconomic status in white girls, whereas no clear relationship was detected in black girls. These findings raise new questions regarding the correlates of obesity in black girls.

Black People↗
PubMed1996

Correlates of the hemodynamic determinants of blood pressure.

The purpose of this study was to investigate the association of sex, race, lean body mass, and fat mass with the hemodynamic determinants of blood pressure, including stroke volume, heart rate, and total peripheral vascular resistance. The study included 201 subjects aged 6 to 17 years, 105 of whom were male and 98 of whom were black. Lean body mass and fat mass were both significant (P < .05) independent determinants of stroke volume, cardiac output, and total peripheral vascular resistance. However, the direction of the effect of lean body mass was opposite for stroke volume and cardiac output compared with that of total peripheral vascular resistance. The direct relationship of lean body mass with systolic blood pressure (SBP) and diastolic blood pressure (DBP) (regression coefficients, 0.55 +/- 0.05 for SBP and 0.47 +/- 0.05 for DBP) indicates that the effect of lean body mass on cardiac output may predominate. Lean body mass explained substantially more of the variance of the hemodynamic variables than did fat mass. After control for the effects of body size, male subjects had higher heart rate and cardiac output, and female subjects had higher vascular resistance. White subjects had higher stroke volume and cardiac output, and black subjects had higher peripheral vascular resistance. This study demonstrates that lean body mass is a more important correlate of the hemodynamic determinants of blood pressure than is fat mass and that sex and race have significant independent relationships with the hemodynamic determinants of blood pressure in children and adolescents.

Adolescent↗
PubMed1996

Weight modification efforts reported by black and white preadolescent girls: National Heart, Lung, and Blood Institute Growth and Health Study.

OBJECTIVE: This study tested four hypotheses: (1) a high percentage of 9- and 10-year-old girls are already trying to lose weight; (2) more white tha black girls are trying to lose weight; (3) more black than white girls are trying to gain weight; and (4) weight modification efforts of preadolescent girls are influenced by factors other than race, such as maternal criticism, body dissatisfaction, and socioeconomic status. DESIGN: Cross-sectional analysis of baseline data on 2379 girls 9 and 10 years of age, which consisted of 1213 black and 1166 white enrollees. RESULTS: Black girls were taller and heavier and showed earlier signs of puberty than white girls but were less dissatisfied with their weight, body shape, and body parts. Approximately 40% of 9- and 10-year-old girls reported that they were trying to lose weight. Of those girls classified in the fourth quartile of body mass index (BMI), approximately 75% were trying to lose weight. After adjusting for BMI, no significant black and white differences in the prevalence of those trying to lose weight were seen, but significantly more black than white girls were trying to gain weight. Multiple logistic regression identified a high BMI, the mother telling her she was too fat, and body dissatisfaction as the major factors associated with trying to lose weight. However, chronic dieting was only associated with a high BMI and the mother telling her she was too fat. An important predictor of girls who were trying to gain weight was being black, along with having a low BMI and the mother telling her she was too thin. CONCLUSIONS: Attempts at gaining weight are much more frequent among black preadolescent girls than their white counterparts. No racial difference was found between black and white girls in their efforts to lose weight or to practice chronic dieting. Because approximately 40% of 9- and 10-year-old girls are already trying to lose weight, pediatricians should capitalize on this concern by providing information on proper weight control techniques. Educational efforts should be directed to both the mother and the child, because weight control efforts of preadolescent girls are stimulated by their mothers' admonitions of being too fat or too thin. The high prevalence of dieting among the thinnest adolescent girls also needs to be addressed by pediatricians.

Black or African American↗