Biomedical subjects

L D Hammer

Publications and source records attributed to L D Hammer.

30 records · Page 2Linked to original sources

PubMed1991

Impact of pubertal development on body fat distribution among white, Hispanic, and Asian female adolescents.

Variation in the waist/hip ratio (WHR) may be related to changes in hormonal secretion associated with pubertal maturation. We therefore studied the effects of race, pubertal development, and body fatness on WHR during adolescence in a multiethnic population. A total of 688 white, Asian, and Hispanic female adolescents (mean (+/- SD) 12.4 +/- 0.7 years), participating in the evaluation of a multisite school-based health education program, were included in these analyses. Self-assessed stage of puberty and measurements of height, weight, waist circumference, and hip circumference were obtained from each participant. The WHR and age-adjusted body mass index were calculated. Analysis of covariance demonstrated that puberty significantly affects hip circumference and WHR but not waist circumference among female adolescents. Age and fatness, as reflected by age-adjusted body mass index, contributed significantly to both circumferences and to the WHR. There was a significant effect of ethnicity on hip circumference but not on waist circumference or the WHR. These results confirm that pubertal stage exerts a significant effect on the hip circumference and WHR in female adolescents, even after the effects of fatness and age are controlled. Studies of body fat distribution during late childhood and adolescence should include assessments of pubertal maturation.

Adipose Tissue↗

PubMed1991

Insulin-like growth factor-I as a reflection of body composition, nutrition, and puberty in sixth and seventh grade girls.

Large variations in nutritional intake have profound effects on the GH-insulin-like growth factor-I (IGF-I) axis in children and adults, but the effect of normal variations in nutrition on IGF-I concentrations is largely unstudied, particularly during puberty. We measured serum IGF-I concentrations in 325 sixth and seventh grade girls (12.4 +/- 0.7 yr) at the beginning of a multisite school-based health curriculum. The mean serum IGF-I level among the 243 girls with complete data was 573 +/- 244 micrograms/L. Pubertal stage was significantly associated with IGF-I (P less than 0.0001, by analysis of variance). Mean concentrations rose from 427 +/- 198 micrograms/L among those at the earliest pubertal stages to 639 +/- 219 micrograms/L among the mature girls. After adjusting for the association with the stage of pubertal development, serum IGF-I was not significantly associated with measures of body composition (body mass index, triceps skin fold thickness, waist/hip ratio, height, and weight). Additionally, IGF-I concentrations were not associated with nutritional intake (total calories, total protein, total fat, and total carbohydrate) or such measures of nutrition as serum iron, hemoglobin, red cell mean corpuscular volume, white cell count, and cholesterol. IGF-I concentrations, however, were significantly correlated with transferrin concentrations, another possible index of nutritional status (r = 0.29; P less than 0.0001). IGF-I is not a clinically useful index of nutritional status among normal pubertal girls.

Adolescent↗

PubMed1990

Influence of early feeding style on adiposity at 6 years of age.

In a previous study we found that a vigorous infant feeding style measured in the laboratory at 2 and 4 weeks of age predicted the degree of adiposity at 1 and 2 years of age. A follow-up of this cohort of infants at 3 and 6 years of age is now reported. Factors predicting adiposity, measured by body mass index at 3 years of age, were pressure of suckling, with high-pressure sucking (denoting a vigorous feeding style) associated with greater adiposity, and time of introduction of solid food, with delayed introduction of solid food or breast-feeding longer than 5 months, or both, being associated with greater adiposity. Predictive factors at 6 years of age were adiposity at birth, with greater adiposity at birth predicting greater fatness at 6 years, parental education, with less education associated with fatness, and a prolonged period of breast-feeding with delayed introduction of solid food. These factors accounted for 40.4% of the variance in adiposity at 3 years of age and 31.2% at 6 years. The effects of social learning on body mass index, indicated by parental educational level, appear to strengthen over time, whereas the effects of the vigorous feeding style wane.

Body Height↗

PubMed1988

Elevated serum iron concentration in adolescent alcohol users.

Alcohol is a frequently abused drug among adolescents. In adults, alcohol alters iron metabolism, predisposing to excess hepatic iron storage and, possibly, liver damage. The purpose of this study was to determine whether alcohol is associated with an elevated serum iron concentration and transferrin saturation in adolescents, and to determine the contribution of oral contraceptive use to these abnormalities. Adolescents (591 male and 614 female) aged 16 to 19 years, who participated in the first National Health and Nutrition Examination Survey from 1971 to 1973, were grouped according to their reported frequency of alcohol intake. Drinking frequency was associated with serum iron concentrations in boys and girls, and with total iron-binding capacity, transferrin saturation, and hemoglobin concentration in boys. Alcohol use was associated with an elevated serum iron concentration only in oral contraceptive nonusers. Adolescents who use alcohol have an elevated serum iron concentration, and male alcohol users have an increased transferrin saturation as well. These abnormalities may be precursors of hepatic iron overload and chronic liver damage.

Adolescent↗

PubMed1987

Growth curves and adult height estimation for adolescents.

Using data from the large number of adolescents studied in cycle III of the National Health Examination Survey, we utilized a sexual maturity index to develop a set of growth curves that reduce the distortion caused by commingling height data from adolescents maturing at different rates. We also created a set of correction tables to be used with these curves to permit the calculation of an adjusted height percentile that compensates for the effects of the differing rates of pubertal maturation. These adjusted height percentiles should remain more constant throughout puberty than height percentiles obtained from traditional growth curves; they may thus be used to estimate final adult height with only data obtained during routine physical examinations, by assuming that subjects maintain their adjusted height percentile through adolescence to adulthood. Height predictions made in this manner compare favorably with predictions made using two clinically tested algorithms.

Adolescent↗

PubMed1987

Does a vigorous feeding style influence early development of adiposity?

A prospective study of a cohort of healthy infants observed from birth to 2 years of age was carried out to investigate factors influencing the development of early adiposity. Infant suckling was measured in the laboratory twice during the first month of life. Multiple regression analyses revealed that parental educational level and a measure of feeding behavior, the interval between bursts of suckling, accounted for 18% of the variance in triceps skinfold measures at 1 year of age. A lower level of education and shorter interburst interval were associated with increased adiposity. Two feeding variables, pressure of suckling and the number of reported feeds per day, accounted for 21% of the variance in skinfold thickness at 2 years of age. Fewer, but larger, feeds and a higher sucking pressure were associated with a greater degree of adiposity. It seems that a vigorous infant feeding style, consisting of sucking more rapidly, at higher pressure, with a longer suck and burst duration, and a shorter interval between bursts of sucking, is associated with higher caloric intake and greater adiposity. The early development of this feeding style suggests that it may be a genetically endowed behavior. Breast-feeding protected against early adiposity only to the age of 6 months in this cohort of infants.

Birth Weight↗

PubMed1986

Adipose tissue thymidine kinase activity in man.

Thymidine kinase activity was studied during human adipose tissue development. Adipose tissue was obtained from the groin in 81 persons, aged 7 wk through 60 yr. None had a metabolic or growth disorder. Adipose tissue thymidine kinase activity was highest in infants and lowest in adults. Peak thymidine kinase activity was seen in the early postnatal period and a lesser elevation was found in the preadolescent years, coinciding with hypothesized periods of proliferation of preadipocytes in man. In contrast, during adulthood, a time of stable lipid-laden cell number, thymidine kinase activity was lower. Although these adipose tissue samples include both stromal and fat cells, the data support the hypothesis that adipose tissue growth in early infancy is primarily the result of cellular proliferation, and that little cellular proliferation occurs after infancy, except possibly for a brief period prior to adolescence.

Adipose Tissue↗

PubMed1986

Growth and intellectual development.

Data from the National Health Examination Survey (cycles II and III) provided a representative sample of 13,887 US youths (6 to 17 years of age) with which to examine the relationship between height (normalized for age and sex) and measures of intellectual development (Wechsler Intelligence Scale for Children) and academic achievement (Wide Range Achievement Test). Additionally, 2,177 subjects were studied first in cycle II and 2 to 5 years later in cycle III, forming a well-selected longitudinal study group in which to examine any association between linear growth and change in IQ scores. Wechsler Intelligence Scale for Children and Wide Range Achievement Test scores were significantly correlated with height in both cycle II and cycle III. However, no significant association between change in relative height and change in IQ scores could be detected in the longitudinal group. These data suggest that therapies designed to increase height are unlikely to alter measures of intellectual development or academic achievement.

Achievement↗

PubMed1985

Increased lead absorption in children with accidental ingestions.

Children with accidental ingestions exhibit excessive hand-to-mouth behavior. In a lead-burdened environment, hand-to-mouth behavior contributes to increased lead absorption. To test the hypothesis that accidental-ingestion patients experience greater lead absorption than other urban children, 95 children under 6 years of age with recent ingestions of nonlead-containing materials and a matched control group were compared. Ingestors had higher mean blood lead levels than controls (25.0 micrograms/dl versus 22.2 micrograms/dl, P = 0.036) and higher mean erythrocyte protoporphyrin levels (40.6 micrograms/dl versus 28.6 micrograms/dl, P = 0.006). Ingestion victims were more than three times as likely as controls to be classified as having increased lead absorption. Thumb-sucking was twice as common among ingestors as controls (37% versus 19%). These findings indicate that children with accidental ingestions are at greater risk of increased lead absorption than other urban children.

Child, Preschool↗

PubMed1982

Aversions to bitterness and accidental poisonings among preschool children.

Individual differences in responsiveness to bitterness were studied among children with and without histories of accidental ingestion of toxic substances. The oral behaviors of 56 children between the ages of 12 and 41 months were videotaped during two minute test periods with lollipops containing different concentrations of bitter sucrose octaacetate (SOA). Videotapes were scored for mouthing times, numbers of oral contacts and latencies to mouthing for each stimulus. Mouthing time was the most sensitive dependent measure examined. Both groups rejected pops with added SOA, decreasing mouthing times as SOA concentration increased. Mouthing times for children with histories of accidental ingestion were slightly lower overall. These results suggest that lowered reactivity to tastes is not a predisposing factor in accidental ingestions, and that bitter substances have some value as deterrents to ingestion for this age group. Rejection of bitter pops by children closely paralleled ratings of bitterness by adult judges.

Adult↗

PubMedDate not supplied

Predicting onset of drinking in a community sample of adolescents: the role of expectancy and temperament.

We report results of a prospective examination of the influence of outcome expectancy variables and inherited temperaments on the onset of drinking over a 12-month period in a sample of 1,164 high school students. While univariate prospective analysis indicated that drinkers and nondrinkers were different both on measures of outcome expectancy and temperament, multivariate analysis supported, most strongly, a social learning account of the processes influencing the onset and maintenance of drinking behavior in this sample. The multivariate analysis revealed that only expectancies for enhanced social behavior were consistently associated with the onset of drinking from baseline to 12-month follow-up (p < .001). Among all nondrinkers at baseline, those entertaining higher expectancies about the positive effects of alcohol on social interaction were more likely to begin drinking between baseline and follow-up. At present, few, if any, alcohol abuse prevention studies with adolescents have explicitly attempted to alter alcohol expectancies or to establish a link between expectancy and behavior change. Our results suggest that it may be useful to do so.

Adolescent↗

PubMedDate not supplied

Breastfeeding attitudes and knowledge of pediatricians-in-training.

A 15-minute questionnaire was administered to the pediatric housestaff in an academic training program to assess their breastfeeding attitudes, knowledge, and confidence to manage breastfeeding problems. Questionnaires were self-administered and anonymous. The participation rate was 53% (n = 29). Overall, the study participants indicated a supportive attitude toward breastfeeding (2.6 on a 6-point scale where 1 = most supportive and 6 = least supportive). Women agreed more strongly than men that pediatricians should strongly encourage mothers to breastfeed and disagreed more strongly than men that breastfeeding is instinctive. Although supportive of breastfeeding, the housestaff in this study were not knowledgeable regarding breastfeeding management, answering only 53% of the questions correctly. Their self-confidence in this area was appropriately low, with only 14% of the total sample describing themselves as "confident" or "very confident" to manage common breastfeeding problems. Pediatricians-in-training have extremely limited knowledge of breastfeeding management. To be truly supportive of breastfeeding, pediatricians should receive didactic and clinical training in breastfeeding management.

Attitude of Health Personnel↗