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Biomedical subjects

F E Johnston

Publications and source records attributed to F E Johnston.

At least 19 recordsLinked to original sources
PubMed1996

Problems in the aging of skeletal juveniles: perspectives from maturation assessments of living children.

We employ samples of children of known chronological age to demonstrate the significance of random and systematic effects on maturation in both dental and skeletal development. Differences between chronological age for dental age in young healthy Canadian children can be as much as 100% of the actual age of the children. For skeletal development by reference to Greulich-Pyle standards, three samples of known-age children from Mexico document parallel effects: 1) 183 six-year-old children have skeletal-based ages with a 95% confidence interval of 4-8 years; 2) 80% of 217 4.0-4.5-year-old children are underaged by 1-3 years; and 3) 130 children of skeletal age between 39 and 44 months are actually between 4 and 7.4 chronological years of age. The Mexican samples are drawn from a population living under conditions of environmental stress with chronic mild to moderate protein-energy malnutrition and moderate to high levels of infectious disease. These children may parallel those from the past, whose remains are studied by skeletal biologists or paleoanthropologists. Our findings reinforce concerns expressed in extant studies regarding the accuracy of age-at-death reconstructions.

Age Determination by Skeleton↗
PubMed1995

Electronmicroscopic diagnosis of human papilloma virus in verruca plantaris.

The purpose of this study was to identify the human papilloma virus in verruca plantaris by transmission electron microscopy and study the cellular effect of human papilloma virus at both the transmission electron microscopy and light histochemistry level. The authors discuss the cellular pathology in relation to early studies and keratin disorders. Features identified by transmission electron microscopy are consistent with characteristics of human papilloma virus-1.

Adolescent↗
PubMed1989

Fiber and exercise in the treatment of obese adolescents.

The changes in body weight, body fat, lean body mass, and the efficiency index were studied in a sample of 80 obese males and females undergoing four different treatments, using two treatment components: an increase in dietary fiber, and energy expenditure through exercise. In both sexes there was a significant effect of exercise upon body weight and an improvement in the efficiency index. There was also a significant interaction between fiber and exercise in girls, but not in boys. This suggests that the eventual effect of dietary fiber is heightened by exercise, as corroborated by significant differences in some of the groups.

Adolescent↗
PubMed1988

Body fat deposition in adult obese women. I. Patterns of fat distribution.

Fat patterning was studied in a sample of 76 obese women before and after weight reduction by principal components analysis. Circumferences were selected as variables rather than skinfolds because circumferences correlated more highly with body composition determined either by total body water or total body potassium. A separate sample of 136 males and females, measured once, was employed to validate the results. The validation sample yielded similar findings. Two significant components were found, the first contrasting upper and lower fatness and the second trunk and extremity fatness. Waist circumference was the best predictor of upper-body fat patterning. For the lower body, thigh circumference loaded more highly than did the iliac crest circumference. Arm circumference did not contribute significantly to upper-lower fat patterning.

Adipose Tissue↗
PubMed1988

Body fat deposition in adult obese women. II. Changes in fat distribution accompanying weight reduction.

This study examined changes in body fat distribution in 68 women who lost an average of 12.3 kg from an initial weight of 103.6 kg. Weight reduction was accompanied by a small but statistically significant reduction of 1.2% in the waist-to-hip ratio, suggestive of a reduction in upper-body obesity. Subjects with greater upper-body obesity tended to achieve greater reductions in the waist-to-hip ratio. Changes in five circumference measures were highly correlated with losses of fat and showed that subjects with lower-body obesity tended to lose large amounts of fat from both their upper and lower fat depots while subjects with upper-body obesity lost fat primarily from their upper depots. Women with lower-body obesity tended to lose more total body fat than did women with upper body obesity (r = -0.26, p less than 0.04).

Adipose Tissue↗
PubMed1987

Interaction of nutritional and socioeconomic status as determinants of cognitive development in disadvantaged urban Guatemalan children.

The relationship between nutritional status, measured by height for age, and cognition, measured by WISC full-scale IQ, was studied in a longitudinal sample of 459 urban Guatemalan children, aged 4-9 years, from a disadvantage community of the fringe of Guatemala City, examined annually over a 3 year period. Socioeconomic status (SES) was controlled by developing a composite index for each home. The mean IQ differed significantly from the lowest to the highest quartiles of stature, the difference between the two extreme quartiles being approximately 0.3 SD of IQ. There was a significant interaction between SES and stature in their effects on IQ. Whereas nutritional status and SES affected IQ in an additive fashion in the upper three SES quartiles, there was no difference in IQ attributible to stature among children from the most disadvantaged homes. This analysis indicates that the mild-to-moderate protein-energy malnutrition (defined by height for age) that is prevalent among children from disadvantaged environments in developing countries is significantly related to cognitive development. However, in the poorest homes, SES is seen as a more important determinant of cognitive development than stature.

Child↗
PubMed1985

Interobserver reliability of skinfold measurements in infants and young children.

Interobserver reliabilities were determined for the triceps, biceps, subscapular, suprailiac, and abdominal skinfolds in 77 children, 9-24 months of age. Technical errors of measurement (replicate variances) and coefficients of variation were compared to data on 12-17-year-olds from the U.S. Health Examination Survey (HES) to 2.5-7-year-old Guatamalan children. Of the five skinfolds, the between-observer variation was not significantly different from zero in four; in the case of the biceps fold, F-ratio was significant at p less than .01. Errors of measurement are less for these data than for the HES or Guatemalan studies. This difference is attributed to the larger means of the older children and youth, as well as to the greater error of measurement shown to exist for larger skinfolds.

Adolescent↗
PubMed1985

Directional asymmetry of body dimensions among white adolescents.

Asymmetry of paired dimensions has been recognized as a methodological problem in anthropometry and more recently as an indicator of environmental stress. This study seeks to determine the extent of directional asymmetry for some of the measurements commonly made in anthropometry. Upper arm circumference, biepicondylar breadth, triceps and subscapular skinfolds, bicondylar breadth of the femur, and calf circumference were measured on right and left sides among 135 white adolescents from suburban Philadelphia. Handedness (right or nonright) was subject-assessed. Body composition was estimated through underwater weighing. Asymmetry was evaluated using a paired t test. Arm measurements are significantly asymmetric in favor of the right side; subscapular skinfolds and leg measurements are not significantly asymmetric. Among the sample of right-handed subjects (n = 116), upper arm circumference and biepicondylar breadth were significantly larger on the right side, and, among the males of this subsample, triceps was as well. The nonright-handed subjects (n = 19) did not show statistically significant asymmetry. Asymmetry was negatively but weakly related to body composition. These results are consistent with an explanation in terms of preferred use of one side of the body and consequent muscle hypertrophy, but an adequate test of this explanation requires hypothesis testing in larger samples of nonright-handed subjects.

Adolescent↗
PubMed1985

Growth status of disadvantaged urban Guatemalan children of a resettled community.

This paper reports the physical growth and body composition from the first year of longitudinal study of 519 Guatemalan children, and their families, from a disadvantaged urban community consisting largely of refugees of the 1976 earthquake. Four cohorts are described, composed of children of 1,3,5, and 7 years at examination. The children are smaller, weigh less, and have reduced fat stores compared either to NCHS reference data or to upper SES Guatemalan children. Stature (or length) and head circumference deviate more from reference data than do triceps or upper arm muscle circumference. Greater deviations are found in the linear dimensions of males than of females. These children are the smallest yet described from Guatemala City, though they are slightly larger than available rural samples. This suggests a continuum of environmental effects acting upon the growth of children of differing socioeconomic levels.

Age Factors↗
PubMed1985

Validity of triceps skinfold and relative weight as measures of adolescent obesity.

The ability of relative body weight and triceps skinfold thickness to indicate obesity in adolescents was analyzed in 169 males and 66 females, 12-17 years of age, whose percent body fat had been determined by underwater weighing. Using 25% body fat in males and 30% in females as the criterion for obesity, 31 males and 17 females were placed in this category. Of these, the triceps skinfold correctly identified 15 males and 4 females, and the relative weight identified 16 and 5, respectively. These anthropometric indicators, at the levels applied, are low in sensitivity (23-50%) but high in specificity (85-100%).

Adolescent↗
PubMed1985

Health implications of childhood obesity.

Childhood obesity has immediate and long-term health risks, There is an increased risk of disease and emotional stress associated with obesity during the growing years, but there are greater risks if obesity continues into adolescence and adulthood. There are insufficient data to quantify the association of childhood and adult obesity. Although obese adults are more likely to have been heavy as children, most overweight children are of normal weight as adults. Childhood obesity is frequently associated with an accelerated growth pattern characterized by increased lean body mass, greater stature, and more rapid maturation.

Adipose Tissue↗
PubMed1984

Differences in the mean fat cell diameter of males between 1 and 48 months of age.

The mean fat cell diameter was determined from measurements of abdominal adipose cells, obtained during inguinal hernia repair, of 126 white and 95 black males ranging in age from 1 through 48 months of age. The mean diameters of black and white subjects did not differ significantly, suggesting that differences in fatness among adults of these two ethnic groups have their origin beyond the age range of this study. The mean fat cell diameter increased through the 6-8 month age group, decreased until the end of the first year, and then levelled off through 48 months of age. Comparison of this curve with those for the triceps, subscapular, abdominal, and suprailiac skinfolds of the same subjects showed generally parallel courses except for the triceps, which continued to increase in size after the means of fat cell diameters and the other skinfolds had levelled off. Our data indicate that changes in body fatness on the trunk at least in the first 4 years of life may be accounted for by changes in fat cell size.

Abdominal Muscles↗
PubMed1984

Heart rate and sleep time: their relationship with growth and adiposity in male infants.

In a clinical trial based on the direct relationship between heart rate activity and energy expenditure during awake and asleep states, 21 healthy 18-month-old infants had their heart rate monitored over a period of 24 h and correlated with their nutritional intake, growth parameters, and measurements of adiposity (fat cell size and skinfold thickness). Infants with higher 24-h and asleep heart rates had smaller fat cells (r = -0.50) and skinfold thickness (abdominal r = -0.70, suprailiac r = -0.80, triceps r = -0.67). Infants with higher relative weight had higher heart rates during awake periods (r = 0.60). Infants sleeping for longer periods had higher weight gain velocity from birth (r = 0.51) and higher relative weight (r = 0.54). This study demonstrates the heart rate activity and duration of sleep are related to growth and adipose tissue deposition during infancy.

Adipose Tissue↗
PubMed1983

The utility of cross-sectional measurements of weight and length for age in screening for growth failure (chronic malnutrition) and clinically severe protein-energy malnutrition.

The accuracy of identifying children with growth failure and/or clinically severe protein-energy malnutrition (PEM) from a single measure of length or weight for age from birth to 36 months was determined. Growth data were treated cross-sectionally and compared with National Center for Health Statistics growth standards in order to determine the sensitivity, specificity and positive predictive value of a single cross-sectional measure of weight-for-age or length-for-age in identifying children diagnosed via longitudinal records. Under 6 months of age, neither weight nor length for age was an adequate predictor of growth failure or clinical malnutrition; from 12 to 36 months, screening measures based on anthropometry were much improved. It was concluded that a single measure of weight or length for age taken close to the first birthday could identify up to 78% of the future second and third year cases of clinically severe PEM. Implications and limitations are discussed.

Body Height↗
PubMed1982

The relationship of body fat weight, determined densitometrically, to relative weight and triceps skinfold in American youths, 12-17 years of age.

The relationship between fat weight, measured densitometrically, and the triceps skinfold and Quetelet's Index has been analyzed by means of linear regression analysis of 235 American youths, 12-17 years of age; 48 males and 41 females were from Minneapolis and 121 males and 25 females from the Greater Philadelphia area. Validation was accomplished by using the results of 10 separate regression analysis, each on 90% of the sample, the remaining 10% serving in each instance as the validation group; this is known as the Jackknife Method. When the Minneapolis and Philadelphia components were pooled, suitable regression models were derived with standard deviations of the errors of prediction of 3.330 kg in males and 2.056 in females. When the sample was subdivided by city the SD's remained essentially the same, but the mean errors were larger. It is concluded that the linear regression models can be used on closely similar populations to estimate fat weight for groups, but estimates for individuals may be expected to have an error of +/- 5-6 kg (i.e., 2 SD's) and are therefore not likely to be suitably accurate for use. The regression weights indicate a greater contribution of the triceps skinfold to fat weight than of Quetelet's Index in males. In females the reverse was found. This may affect sex differences in prevalence rates of obesity, if the diagnosis is based upon a single anthropometric indicator.

Adipose Tissue↗