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Biomedical subjects

W B Strong

Publications and source records attributed to W B Strong.

At least 73 records · Page 4Linked to original sources
PubMed1990

Dietary assessment instruments for preschool children: reliability of parental responses to the 24-hour recall and a food frequency questionnaire.

Nutrient intakes of preschool-age children were assessed with a 24-hour dietary recall and a 3-month food frequency questionnaire (FFQ). Parents of 55 preschoolers (mean age = 4.25 +/- 0.59 years) completed the recall and FFQ on two occasions 1 week apart. The recalls and FFQs were analyzed for energy, cholesterol, protein, total carbohydrate, calcium, sodium, potassium, and saturated, polyunsaturated, and monounsaturated fats; each nutrient was expressed as raw value, value per kg body weight, and value per 1,000 kcal. Test-retest reliability estimates for the 24-hour recall indicated significant variability in reported total energy intake, but stable reports of intake were observed for one or all units of expression for polyunsaturated fats, cholesterol, protein, total carbohydrate, calcium, and potassium. The FFQ showed significant positive test-retest reliability estimates for all nutrients for all units of expression. Comparison of the recall and FFQ data showed similar percentages of intakes of energy from fat, carbohydrate, and protein and significant correlations for reported intakes of cholesterol, protein, calcium, and potassium. Comparison of the recall and FFQ data with recall data from a comparable cohort showed lower reported intakes for our sample, with the exception of protein, carbohydrate, calcium, and potassium. If validation studies are successful, the FFQ may be useful in epidemiological studies of preschoolers' intakes over extended periods. The recall may prove to be a useful tool in the assessment of day-to-day variations in macronutrient intakes.

Calcium, Dietary↗
PubMed1990

Teaching preventive cardiology in the pediatric setting.

This article presents both the rationale behind and a framework for incorporating pediatric preventive cardiology into undergraduate medical education and pediatric residency training. Such education of physicians in the practice of preventive cardiology requires provision of not only didactic information but also training and practice in clinical skills. A combination of didactic lectures, small group discussions, interactive programs utilizing video tapes and computer programs, family and patient simulation, preventive cardiology clinics, and community cardiovascular health promotion activities all help to provide the optimal framework for an effective medical student and pediatric resident training program in pediatric preventive cardiology. Since pediatricians are in the best position to practice true primary prevention of cardiovascular disease beginning in childhood, it is essential that physicians in training understand the concepts and learn the skills needed to practice this critical component of pediatric medicine.

Adolescent↗
PubMed1989

In vitro conversion of formate to serine: effect of tetrahydropteroylpolyglutamates and serine hydroxymethyltransferase on the rate of 10-formyltetrahydrofolate synthetase.

Serine hydroxymethyltransferase and C1-tetrahydrofolate synthase catalyze four reactions which convert formate and glycine to serine. The one-carbon carrier in these reactions if tetrahydropteroylglutamate which is regenerated in the coupled reaction and thus can be used in catalytic concentrations with respect to serine synthesis. The rate of serine synthesis is followed by the oxidation of NADPH during reduction of the intermediate 5,10-methenyltetrahydropteroylglutamate. Km values for the substrates of cytosolic serine hydroxymethyltransferase and the 10-formyltetrahydrofolate synthetase activity of the trifunctional enzyme C1-tetrahydrofolate synthase were determined. This included the values for the polyglutamate forms of tetrahydropteroylglutamate containing from one to six glutamate residues. The results suggest that the synthetase active site binds the polyglutamate forms of the coenzyme synergistically with respect to formate and ATP. Using saturating levels of all substrates, the kcat values for the serine hydroxymethyltransferase and 10-formyltetrahydrofolate synthetase activities were also determined. The synthetase reaction is the rate-determining step in the conversion of formate to serine. The effect of glutamate chain length and the concentration of serine hydroxymethyltransferase were studied with respect to the rate of serine formation. Tetrahydropteroylmonoglutamate gave slower than expected rates which is attributed to its inhibition of the reduction of the intermediate 5,10-methenyltetrahydropteroylglutamate. This inhibition was not a factor with the di- through hexaglutamate forms of the coenzyme. The addition of an excess of serine hydroxymethyltransferase was predicted to lower the rate of the formation of serine by lowering the concentration of free coenzyme in the assay. However, activation of the rate was observed which was at least 2-fold greater than the predicted rate. This increase in predicted rate appears to result from an interaction between C1-tetrahydrofolate synthase and serine hydroxymethyltransferase. The in vivo concentrations of serine hydroxymethyltransferase and C1-tetrahydrofolate synthase in rabbit liver were determined.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed1989

Interaction of tetrahydropteroylpolyglutamates with two enzymes from mitochondria.

The dissociation constants of tetrahydropteroylpolyglutamates, having from one to six glutamate residues, have been determined for the two mitochondrial enzymes serine hydroxymethyltransferase and dimethylglycine dehydrogenase. The ratios of the dissociation constants for the mono- and hexaglutamate forms of the coenzyme were 200 and less than 10 for serine hydroxymethyltransferase and dimethylglycine dehydrogenase, respectively. Km and kcat values were determined for the reversible interconversion of serine and glycine as a function of the number of glutamyl residues on the coenzyme. The values in the serine to glycine direction did not significantly change with the number of glutamyl residues, but in the glycine to serine direction, there was a 9-fold increase in the kcat/Km when the longer chain polyglutamates were used as the coenzyme substrate. A sensitive and rapid method for determining the dissociation constants of proteins which bind either tetrahydropteroylpolyglutamates or their 5-methyl and 5-formyl conjugates is described.

Animals↗
PubMed1989

Exercise-induced differences in cardiac output, blood pressure, and systemic vascular resistance in a healthy biracial population of 10-year-old boys.

Previous studies have documented systolic blood pressure differences in response to dynamic exercise when blacks were compared with whites. This study was performed to validate these data and to determine if the cardiac output and systemic vascular resistance responses to exercise are different in a biracial population of 10-year-old boys. Nineteen blacks and 31 whites underwent maximum supine graded exercise tests with Doppler determination of cardiac output and measurement of systolic and diastolic blood pressure and systemic vascular resistance. The blacks had a body surface area that was marginally larger than that of the whites, but no differences were noted in height or weight. Working capacities, when indexed by weight, were virtually identical between the two groups. No differences were noted in either systolic or diastolic blood pressure during preexercise, maximum exercise, or early and late recovery. White males had significantly higher cardiac indexes during preexercise, maximum exercise, and early and late recovery. Black males had greater systemic vascular resistance during preexercise, maximum exercise, and early and late recovery. Thus, the black children's blood pressure responses to exercise were comparable with those of the white children but they had a greater systemic vascular resistance and lower cardiac index. These racial differences may serve as potential markers for the prehypertensive state.

Anthropometry↗
PubMed1989

Racial differences in young children's blood pressure. Responses to dynamic exercise.

Studies have observed that black children exhibit greater blood pressure increases in response to dynamic exercise than white children. Seventy-five (51 white, 24 black) children aged 4 to 6 years old had their blood pressure and heart rate measured before, during, and 5 minutes after dynamic upright exercise on the treadmill. Girls had higher preexercise heart rate values than the boys, and showed a marginally slower recovery of diastolic blood pressure values. Black children had significantly lower preexercise and peak exercise heart rate values, higher systolic blood pressure values at peak exercise, and greater systolic blood pressure increases in response to exercise than did white children. These differences are discussed in terms of mechanisms that may be responsible for racial differences in essential hypertension.

Black People↗
PubMed1989

Interaction of folylpolyglutamates with enzymes in one-carbon metabolism.

Of all the coenzymes, tetrahydrofolate exhibits the most structural diversity. The relationship of these structural forms to physiological function is under intense study by numerous research groups. In textbooks, tetrahydrofolate (tetrahydropteroylmonoglutamate) is shown as the coenzyme of one-carbon metabolism, but it has been known for several decades that the physiologically active forms of the coenzyme contain from 4 to 7 glutamyl residues linked by amide bonds through the gamma-carboxyl group. These glutamyl residues do not serve a direct function in transferring the one-carbon group. The tetrahydrofolylpolyglutamates were originally thought to be simply storage forms of the coenzyme, but studies now show that the polyglutamate chain of the coenzyme affects the transport properties of the coenzyme, alters the kinetic properties of many enzymes in one-carbon metabolism, and results in channeling of the coenzyme between several enzymes. In general, the dissociation constants of this group of enzymes for the tetrahydrofolylpolyglutamates are very low, in the 0.1 to 1 microM range. The concentration of the coenzyme in the cell appears to be similar to the concentration of folate-utilizing enzymes, suggesting that the concentration of unbound coenzyme in the cell may be very low. Several of the enzymes in one-carbon metabolism are either multifunctional proteins or multienzyme complexes. An active area of research is to determine if there is a functional relationship between these multifunctional enzymes and the polyglutamate portion of the coenzyme.

Carbon↗
PubMed1989

The relationship between hostility and blood pressure in children.

The relationship between two dimensions of hostility and resting blood pressure was examined in 98 children aged 7 to 10 years. The children completed the expressive and experienced hostility subscales of the Buss-Durkee Hostility Inventory and one week later had blood pressure and obesity levels assessed. Multiple regression analyses and analyses of variance showed that expressive hostility was positively associated with blood pressure, although this relationship became marginally significant when the effects of obesity were controlled. A significant inverse relationship was found between experienced hostility and systolic blood pressure. These results are discussed as they relate to findings in adults on hostility and cardiovascular disease and the relationship between hostility, blood pressure, and obesity.

Blood Pressure↗
PubMed1989

Assessment of children's Type A behavior: relationship with negative behavioral characteristics and children and teacher demographic characteristics.

Thirty-two teachers rated Type A behavior, using Matthews Youth Test for Health, (MYTH) and negative characteristics of hyperactivity, negative peer relations, social withdrawal, and depression in 105 children, between the ages of 6 and 11, from lower to middle class Black and White families. Children's age, gender, race, and socioeconomic status (SES) and teachers' gender, grade taught, and years of teaching experience were not related to teachers' MYTH ratings. However, White teachers rated children higher on Type A behavior than Black teachers. Controlling for teacher race effects, MYTH total scores, rather than reflecting a global negative view of the child, showed a strong overlap with hyperactivity and were differentiated from social withdrawal and depression. The MYTH Impatience/Aggression factor was highly related to hyperactivity and negative peer interactions; the Competitiveness factor was associated with a lack of social withdrawal. The conclusions verify the multidimensional nature of children's Type A behavior pattern and the importance of rater demographic characteristics in the assessment of children's behavior.

Black or African American↗
PubMed1989

Validation of a heart rate monitor with children in laboratory and field settings.

The validity of the Sport Tester PE 3000 portable heart rate monitor for use with children was assessed by comparing readings with simultaneously recorded ECG heart rates in three studies, two using laboratory tasks and one in a field setting. Study 1 examined the validity of the Sport Tester with a sample of ten 10-yr-olds performing a cycle ergometer exercise task. Sport Tester readings taken during three 3-min exercise loads were correlated from 0.97 to 0.99 with simultaneously recorded ECG heart rates. In study 2, 23 children from 4 to 6 yr of age performed treadmill exercise for three 1-min intervals while Sport Tester and ECG heart rate data were obtained. Correlations for the three intervals ranged from 0.94 to 0.99. Study 3 obtained ECG and Sport Tester heart rates in 14 7- to 9-yr-olds who engaged in 3-min periods of standing, walking, jogging, throwing a ball, batting a ball, and playing on a jungle gym. Significant correlations of at least 0.98 between Sport Tester and ECG heart rates were obtained during all six activities. For all three studies, standard errors of estimate were low, ranging from 1.1 to 3.7 beats.min-1. For individuals, maximum differences ranged from 0 to 12.4 beats.min-1. Collectively, these findings indicate that the Sport Tester provides valid readings of young children's heart rates across a wide range of exercise involving upper- and lower-body movements.

Child↗