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Biomedical subjects

Terry T-K Huang

Publications and source records attributed to Terry T-K Huang.

15 recordsLinked to original sources
PubMed2006

Longitudinal changes in insulin sensitivity, insulin secretion, and beta-cell function during puberty.

OBJECTIVE: To determine longitudinal changes in insulin sensitivity (SI), insulin secretion, and beta-cell function during puberty in white and black youth. STUDY DESIGN: The tolbutamide-modified frequently sampled intravenous glucose tolerance test and minimal modeling were used to measure SI, the acute insulin response to glucose (AIRg), and beta-cell function (disposition index, DI) in white (n = 46) and black (n = 46) children (mean [+/-SD] age at baseline = 10.2 +/- 1.7 years). Growth curve models (including 272 observations) with SI, AIRg, and DI regressed on Tanner stage were run after adjusting for covariates. RESULTS: After adjusting for covariates, growth curve models revealed that SI decreased and subsequently recovered by the end of puberty in whites and blacks (both p < .05), AIRg decreased linearly across Tanner stages in both races (both p < .001), and DI decreased across puberty in blacks (p = .001) but not in whites (p = .2). CONCLUSIONS: White and black youth exhibited transient insulin resistance and diminished AIRg during puberty. The progressive decline in DI among blacks versus whites may reflect a unique effect of puberty on beta-cell compensation in blacks. Future studies are needed to identify whether this difference contributes to the increased risk of type II diabetes in young blacks.

Black or African American↗
PubMed2006

Associations of adiposity with measured and self-reported academic performance in early adolescence.

OBJECTIVE: To examine the associations of adiposity with measured and self-reported academic performance independently of demographics and physical activity among U.S. adolescents. RESEARCH METHODS AND PROCEDURES: We surveyed 666 students 11 to 14 years old from seven middle schools in Los Angeles, CA. Weight and height were measured. Actual grade point average was obtained from school records. Self-reported school grades and physical activity time were measured by questionnaire. Adiposity measures included BMI, BMI percentile (> or =85th percentile defined as at-risk-of-overweight), and percentage body fat (bioimpedance). RESULTS: After adjusting for gender, ethnicity, age, and physical activity time, overweight at-risk status, BMI, and percentage body fat were negatively related to only self-reported (p < 0.01) but not measured grades. Level of moderate-to-vigorous physical activity time was negatively related to measured and self-reported grades, independently of adiposity (p < 0.01). DISCUSSION: To our knowledge, this is the first study to examine both body mass and body fat in relation to measured and self-reported school grades. Adiposity did not relate to actual academic performance in a sample of predominantly Latino and Asian-American adolescents. The use of measured vs. self-reported academic outcomes may represent different constructs and influence study conclusions. Cultural factors may also play a role in our findings, but this requires further study.

Achievement↗
PubMed2006

Smoking, weight loss intention and obesity-promoting behaviors in college students.

OBJECTIVE: To examine whether college smoking was associated with trying to lose weight and other weight-related behaviors. METHODS: We surveyed 300 students at the University of Kansas about smoking (ever, current, and amount), weight loss intention (y/n), weight-related attitudes, and eating and exercise behavior. Weight, height, and body fat were measured. RESULTS: About half the students (49%) self-identified as having ever smoked while 53 (17.6%) self-identified as current smokers. After controlling for sex, age, and ethnicity, ever smoking was not related to weight loss intention but was associated with greater pressure to maintain a healthy weight (p = 0.05), and having engaged in mild exercise on more days in the previous year (p = 0.05). Compared to nonsmokers, current smokers ate more at restaurants serving high calorie foods (p < 0.05) and ate more frequently in front of the TV (p < 0.01). Amount smoked was related to diminished use of exercise facilities (p = 0.03) and more frequent eating at restaurants serving high calorie foods (p < 0.05) and in front of the TV (p = 0.01). CONCLUSIONS: Current smoking among college students was related to weight loss intention. Despite wanting to lose weight, current smoking was concomitant with obesity-promoting behaviors such as eating higher calorie foods and eating in front of the TV. College-based interventions to prevent smoking initiation or promote smoking cessation should include a focus on healthy eating, exercise and healthful ways to lose or maintain weight.

Adolescent↗
PubMed2005

Dietary fiber and fat are associated with excess weight in young and middle-aged US adults.

OBJECTIVE: To examine relative associations of dietary composition variables with body mass index (BMI; calculated as kg/m2) among young and middle-aged US adults. We hypothesized that in subjects with physiologically plausible reported energy intakes, fiber intake would be inversely associated with BMI, independent of other dietary composition and sociodemographic variables. SUBJECTS AND DESIGN: Data from adults age 20 to 59 years in the Continuing Survey of Food Intakes by Individuals (CSFII) 1994-1996 were used. Exclusions were pregnancy or lactation, food insecurity, missing weight or height data, or having only one dietary recall. Based on our previously published methods, a physiologically plausible reported energy intake was calculated as being within +/-22% of predicted energy requirements for the mean of two 24-hour recalls. RESULTS: Reporting plausibility ([reported energy intake/predicted energy requirements]x100) averaged 83% in the total sample (N=4,539) and increased to 96% in the plausible sample (n=1,932). Only approximately 5% of the plausible sample consumed the Adequate Intake for fiber. In plausibly reporting women, fiber, its interaction with percentage energy from fat, and energy density were independently associated with BMI. Only percentage energy from fat was associated with BMI in men reporting plausibly. Compared with the total sample, stronger relationships between diet and BMI were observed among the plausible reporters. In women, a low-fiber (< 1.5 g/MJ), high-fat (> or = 35% energy) diet was associated with the greatest increase in risk of overweight or obesity compared with a high-fiber, low-fat diet. CONCLUSIONS: Weight control advice for US women should place greater emphasis on consumption of fiber.

Adult↗
PubMed2005

Effect of screening out implausible energy intake reports on relationships between diet and BMI.

OBJECTIVE: We present an updated method for identifying physiologically implausible dietary reports by comparing reported energy intake (rEI) with predicted energy requirements (pER), and we examine the impact of excluding these reports. RESEARCH METHODS AND PROCEDURES: Adult data from the Continuing Survey of Food Intakes by Individuals 1994 to 1996 were used. pER was calculated from the dietary reference intake equations. Within-subject variations and errors in rEI [coefficient of variation (CV) approximately 23%] over 2 days (d), pER (CV approximately 11%), and measured total energy expenditure (mTEE; doubly labeled water, CV approximately 8.2%) were propagated, where +/-1 SD = CV2(rEI)/d + CV2(pER) + CV2(mTEE) = +/-22%. Thus, a report was identified as implausible if rEI was not within 78% to 122% of pER. Multiple cut-offs between +/-1 and +/-2 SD were tested. RESULTS: %rEI/pER = 81% in the total sample (n = 6499) and progressively increased to 95% in the +/-1 SD sample (n = 2685). The +/-1 to 1.4 SD samples yielded rEI-weight associations closest to the theoretical relationship (mTEE to weight). Weak or spurious diet-BMI associations were present in the total sample; +/-1 to 1.4 SD samples showed the strongest set of associations and provided the maximum n while maintaining biological plausibility. DISCUSSION: Our methodology can be applied to different data sets to evaluate the impact of implausible rEIs on health outcomes. Implausible rEIs reduce the overall validity of a sample, and not excluding them may lead to inappropriate conclusions about potential dietary causes of health outcomes such as obesity.

Adult↗
PubMed2005

Additive interactions of maternal prepregnancy BMI and breast-feeding on childhood overweight.

OBJECTIVE: To examine the interactions of maternal prepregnancy BMI and breast-feeding on the risk of overweight among children 2 to 14 years of age. RESEARCH METHODS AND PROCEDURES: The 1996 National Longitudinal Survey of Youth, Child and Young Adult data in the United States were analyzed (n = 2636). The weighted sample represented 51.3% boys, 78.0% whites, 15.0% blacks, and 7.0% Hispanics. Childhood overweight was defined as BMI >/=95th percentile for age and sex. Maternal prepregnancy obesity was determined as BMI >/=30 kg/m(2). The duration of breast-feeding was measured as the weeks of age from birth when breast-feeding ended. RESULTS: After adjusting for potential confounders, children whose mothers were obese before pregnancy were at a greater risk of becoming overweight [adjusted odds ratio (OR), 4.1; 95% confidence interval (CI), 2.6, 6.4] than children whose mothers had normal BMI (<25 kg/m(2); p < 0.001 for linear trend). Breast-feeding for >/=4 months was associated with a lower risk of childhood overweight (OR, 0.6; 95% CI, 0.4, 1.0; p = 0.06 for linear trend). The additive interaction between maternal prepregnancy obesity and lack of breast-feeding was detected (p < 0.05), such that children whose mothers were obese and who were never breast-fed had the greatest risk of becoming overweight (OR, 6.1; 95% CI, 2.9, 13.1). DISCUSSION: The combination of maternal prepregnancy obesity and lack of breast-feeding may be associated with a greater risk of childhood overweight. Special attention may be needed for children with obese mothers and lack of breast-feeding in developing childhood obesity intervention programs.

Adolescent↗
PubMed2004

Reading nutrition labels and fat consumption in adolescents.

We studied the relationship between reading nutrition labels and percent calorie intake from fat. In adolescent boys, reading nutrition labels was associated with higher fat intake. In girls, fat intake did not differ by frequency of nutrition label reading. Nutrition label reading does not translate into healthier diet in adolescents.

Adolescent↗
PubMed2004

Energy intake and meal portions: associations with BMI percentile in U.S. children.

OBJECTIVE: We examined relationships of eating patterns and reported energy intake (rEI) with BMI percentile in U.S. children. RESEARCH METHODS AND PROCEDURES: Two 24-hour dietary recalls from the Continuing Surveys of Food Intakes by Individuals 1994 to 1996 and 1998 (1005 boys, 990 girls) were averaged, and children were categorized into three age groups: 3 to 5 years (n = 1077), 6 to 11 years (n = 537), and 12 to 19 years (n = 381). Physiologically implausible reports due to reporting bias or abnormal intake (rEI outside +/-18% to 23% of predicted energy requirements; pER) were identified. RESULTS: rEI averaged 109 +/- 34% and 100 +/- 10% of pER in the total and plausible samples, respectively. EI was overreported more in younger children and underreported more in overweight older children. Children with plausible rEI (45.3% of sample) averaged 4.7 eating occasions/d, 589 kcal/meal, 223 kcal/snack, and 2038 kcal/d. rEI was not associated with BMI percentile in the total sample. In the plausible sample, rEI, meal portion size, and meal energy were positively associated with BMI percentile in boys 6 to 11 years and in children 12 to 19 years. No relationships were found in children 3 to 5 years and girls 6 to 11 years. Relationships were more consistent and stronger in the plausible compared with the total sample. DISCUSSION: Excluding implausible dietary reports may be necessary for discerning dietary associations with BMI percentile. EI and meal, but not snack, patterns may play a quantitatively greater role in weight regulation as children age.

Adolescent↗
PubMed2004

The metabolic syndrome in overweight Hispanic youth and the role of insulin sensitivity.

The prevalence of the metabolic syndrome is highest among Hispanic adults. However, studies exploring the metabolic syndrome in overweight Hispanic youth are lacking. Subjects were 126 overweight children (8-13 yr of age) with a family history for type 2 diabetes. The metabolic syndrome was defined as having at least three of the following: abdominal obesity, low high-density lipoprotein (HDL) cholesterol, hypertriglyceridemia, hypertension, and/or impaired glucose tolerance. Insulin sensitivity was determined by the frequently sampled iv glucose tolerance test and minimal modeling. The prevalence of abdominal obesity, low HDL cholesterol, hypertriglyceridemia, systolic and diastolic hypertension, and impaired glucose tolerance was 62, 67, 26, 22, 4, and 27%, respectively. The presence of zero, one, two, or three or more features of the metabolic syndrome was 9, 22, 38, and 30%, respectively. After controlling for body composition, insulin sensitivity was positively related to HDL cholesterol (P < 0.01) and negatively related to triglycerides (P < 0.001) and systolic (P < 0.01) and diastolic blood pressure (P < 0.05). Insulin sensitivity significantly decreased (P < 0.001) as the number of features of the metabolic syndrome increased. In conclusion, overweight Hispanic youth with a family history for type 2 diabetes are at increased risk for cardiovascular disease and type 2 diabetes, and this appears to be due to decreased insulin sensitivity. Improving insulin resistance may be crucial for the prevention of chronic disease in this at-risk population.

Adolescent↗
PubMed2003

Predicting total body fat from anthropometry in Latino children.

OBJECTIVE: To develop prediction equations for total body fat specific to Latino children, using demographic and anthropometric measures. RESEARCH METHODS AND PROCEDURES: Ninety-six Latino children (7 to 13 years old) were studied. Two-thirds of the sample was randomized into the equation development group; the remainder served as the cross-validation group. Total body fat was measured by DXA. Measures included weight, height, waist and hip circumferences, and skinfolds (suprailiac, triceps, abdomen, subscapula, thigh, and calf). RESULTS: The previously published equation from Dezenberg et al. did not accurately predict total body fat in Latino children. However, newly developed equations with either body weight alone (intercept +/- SE = 1.78 +/- 1.53 kg, p > 0.05; slope +/- SE = 0.90 +/- 0.07, p > 0.05 against slope = 1.0; R(2) = 0.86), weight plus age and gender (intercept +/- SE = 2.28 +/- 1.20 kg, p > 0.05; slope +/- SE = 0.91 +/- 0.05, p > 0.05; against slope = 1.0; R(2) = 0.92), or weight plus height, gender, Tanner stage, and abdominal skinfold (intercept +/- SE = 1.47 +/- 1.01 kg, p > 0.05; slope +/- SE = 0.93 +/- 0.04, p > 0.05; against slope = 1.0, R(2) = 0.97) predicted total body fat without bias. DISCUSSION: Unique prediction equations of total body fat may be needed for Latino children. Weight, as the single most significant predictor, can be used easily to estimate total body fat in the absence of any additional measures. Including age and gender with weight produces an equally stable prediction equation with increasing precision. Using a combination of demographic and anthropometric measures, we were able to capture 97% of the variance in measured total body fat.

Absorptiometry, Photon↗
PubMed2002

Effect of changes in fat distribution on the rates of change of insulin response in children.

OBJECTIVE: To develop mixed models for examining longitudinal associations between rates of change in visceral, subcutaneous abdominal, and total body fat with rates of change in fasting insulin (FI) and insulin sensitivity (SI) over 3 years in children. RESEARCH METHODS AND PROCEDURES: Seventy-seven children (mean age, 8.3 years at baseline) from Birmingham, Alabama, with three or more annual measures of FI and SI were included. Abdominal fat was measured by computed tomography, and total body fat and lean tissue mass were measured by DXA. Mixed models examined the longitudinal associations between the baseline level/rate of change of different fat compartments and the rate of change in FI or SI. RESULTS: An annual increase of approximately 5% in FI was associated with 1 cm(2)/yr of visceral fat gain per year (p < 0.05), independent of subcutaneous abdominal fat. A 1-cm(2) difference in initial subcutaneous abdominal fat was associated with an approximately 0.2% increase per year in FI (p < 0.02), independent of visceral fat. None of the rates of change in any of the fat measures was associated with the rate of change of SI. DISCUSSION: The rate of change in visceral fat was positively associated with the rate of change in FI, independent of increasing subcutaneous abdominal fat; however, subcutaneous abdominal fat may be more predictive of the rate of change of FI than visceral or total fat. Therefore, growth-related increases in abdominal fat, particularly subcutaneous abdominal fat, may contribute to accelerating increases in FI, but have no effect on SI.

Absorptiometry, Photon↗
PubMed2002

Insulin sensitivity and blood pressure in black and white children.

Although insulin sensitivity is correlated with high blood pressure in adults, it is unclear whether such a relationship exists in children across ethnic groups. Therefore, the aims of the study were to establish (1) if body composition and insulin sensitivity were related to blood pressure in children, and (2) if any differences in blood pressure between white and black children were explained by body composition and/or insulin sensitivity. Insulin sensitivity and the acute insulin response were established by the minimal model and body composition by dual-energy X-ray absorptiometry. Blood pressure was recorded in the supine position. Body composition, fasting insulin (P<0.01), and the acute insulin response (P<0.05) were positively related to systolic blood pressure but not to diastolic blood pressure, and insulin sensitivity (P<0.001) was negatively related to systolic blood pressure but not to diastolic blood pressure. Insulin sensitivity was negatively associated with systolic and diastolic blood pressure after adjustment for body composition (P<0.01). Black children had higher systolic (110+/-9.2 versus 105+/-8.5 mm Hg, P=0.01) and diastolic (59+/-7.0 versus 54+/-8.0 mm Hg, P<0.01) blood pressure than did white children. The ethnic difference in blood pressure was not explained by body composition, fasting insulin, acute insulin response, or insulin sensitivity. In conclusion, the relationship between insulin sensitivity and systolic blood pressure is evident early in life. Black ethnicity and low insulin sensitivity contribute independently to higher blood pressure in children.

Analysis of Variance↗
PubMed2002

Development of a prediction equation for insulin sensitivity from anthropometry and fasting insulin in prepubertal and early pubertal children.

OBJECTIVE: To test the utility of homeostasis model assessment (HOMA) in predicting insulin sensitivity [x10(- 4) min(-1)/(microIU/ml)] in children and to develop and compare two new prediction equations for insulin sensitivity in children using demographic and anthropometric measures in the presence or absence of fasting insulin. RESEARCH DESIGN AND METHODS: We studied 156 white and African-American children with complete data (mean age 9.7 +/- 1.8 years, 87.8% Tanner Stage 1 or 2). For development of new equations, two-thirds of the children were randomly assigned to a development group, whereas the remaining children were assigned to a cross-validation group. RESULTS: A modified HOMA equation accurately predicted insulin sensitivity, but its utility is similar to fasting insulin alone. Demographic and anthropometric measures alone did not predict insulin sensitivity accurately, even when precise measures of body composition were included in the prediction model. Ethnicity, calf skinfold, and fasting insulin together explained 73% of the variance in insulin sensitivity and accurately predicted insulin sensitivity. The regression of measured versus predicted insulin sensitivity in the cross-validation group was not significantly different from the line of identity (P > 0.05). Mean difference between measured and predicted insulin sensitivity was also not significant (P > 0.05). Some bias was apparent, particularly in white boys. CONCLUSIONS: Ethnicity, calf skinfold, and fasting insulin can accurately predict insulin sensitivity with greater precision than HOMA or fasting insulin alone (R(2) = 0.73). Future studies, however, are needed to examine whether a universal equation is possible. A cross-validated prediction equation may be useful in population-based studies when complex measures of insulin sensitivity are not available.

Anthropometry↗