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Biomedical subjects

P H Buschang

Publications and source records attributed to P H Buschang.

At least 91 records · Page 5Linked to original sources
PubMed1986

Genetic and environmental effects on growth of children from a subsistence agricultural community in southern Mexico.

Sibling correlations for size attained in height, weight, sitting height, estimated leg length, the triceps skinfold, arm circumference, and estimated midarm muscle circumference were compared in 6- through 13-year-old schoolchildren grouped by household socioeconomic status. The children were residents of a Zapotec-speaking, subsistence agricultural community in the Valley of Oaxaca in southern Mexico. Sibling pairs were classified as being from high and low socioeconomic status (SES) households, and sibling correlations were computed within each SES group controlling for environmental effects derived from a factor analysis of information on household demography and land and livestock holdings. Like-sex siblings from lower SES households have significantly different correlations in four instances. Correlations are higher for leg length in lower SES brothers and higher for sitting height and weight in lower SES sisters, while the correlation for sitting height is higher in upper SES brothers. The sibling correlation results are not entirely consistent with observations on growth status by SES, particularly if the power and similarity of a common environment is the only cause of higher sibling correlations. Reduced body size under poorer socioeconomic and presumably nutritional circumstances is apparent, but it is not possible in this analysis to distinguish whether genotypic (developmental) plasticity or genetic adaptation, or both, are involved.

Adolescent↗
PubMed1986

A polynomial approach to craniofacial growth: description and comparison of adolescent males with normal occlusion and those with untreated Class II malocclusion.

Orthogonal polynomials are used to model the craniofacial growth of adolescent boys, aged 11 through 14 years, and to evaluate variation between normal occlusion and untreated Class II malocclusion. The results show linear growth (velocity) for the maxillary measures; their angular relationships to the cranial base remain stable throughout the age range. Mandibular measures show growth velocity and acceleration, indicating the adolescent growth spurt. For the majority (80%) of measures, boys with normal occlusion and those with Class II malocclusion were not significantly different. Mean growth velocity of basion-nasion is significantly greater for subjects with Class II, Division 1 malocclusion. Total mandibular length and the ANB angle display significant mean size (constant) differences between boys with normal occlusion and boys with untreated Class II malocclusion. The groups are comparable in growth velocity and acceleration, indicating that the size differences are established before 11 years of age and maintained during adolescence.

Adolescent↗
PubMed1985

Socioeconomic variation in the growth status of children in a subsistence agricultural community.

Socioeconomic variation in the growth status of 293 children, 6 through 13 years of age, from a rural subsistence agricultural community in southern Mexico was considered. Socioeconomic status was based on an index developed from landholdings, household goods, and occupation, and households were classified as high and low status. Growth measurements included weight, stature, sitting height, estimated leg length, arm and estimated arm muscle circumferences, triceps skinfold, and right gripping strength. The growth status of boys showed a clear socioeconomic differential, while that of girls did not. The results are consistent with the generalization that males are more influenced by environmental stresses than females, including, of course, the favorable stress of improved socioeconomic circumstances, even within seemingly single-class rural communities.

Adolescent↗
PubMed1985

Interrelationships among measures of somatic, skeletal, dental, and sexual maturity.

The interrelationships among five measures of physiologic maturity for 50 French-Canadian girls are evaluated--menarche, peak height velocity (PHV), 75% skeletal maturity, appearance of the ulnar sesamoid, and 90% dental development. The mean ages of occurrence of the events differed significantly (P less than 0.01). Menarche and 90% dental maturity showed the least variability. Ages of PHV, menarche, and 75% skeletal maturity were significantly correlated (P less than 0.05). Age of menarche was most closely associated with PHV. The appearance of the ulnar sesamoid was highly correlated with 75% skeletal maturity; both were equally related to the ages of PHV and menarche. The age at which French-Canadian girls attain 90% of their dental development showed no significant relationships with the other maturity indicators. The results imply that the mechanisms controlling dental development are independent of somatic and/or sexual maturity.

Adolescent↗
PubMed1985

Estimating variance components with BMDP for analyses of technical reliability.

Measurement reliability reflects the ratio of true (subject) to observed (subject plus error) variance. Analyses of reliability are limited due to difficulties in obtaining accurate estimates of the sources of variation upon which this relationship depends. This paper presents a simple analysis of variance procedure, using BMDP8V, for estimating the necessary variance components of mixed models, from which reliability may be assessed.

Analysis of Variance↗
PubMed1985

Adjusting craniofacial correlations for technical error.

Reliability estimates provide a means of adjusting observed correlations for technical error. The results show that the true correlations among 11 craniofacial landmarks are consistently higher than observed values. Consequently, the regression slopes defining these relationships are also increased. The less reliable two measures are, and the closer their joint reliability approximates the observed correlation, the greater the expected change in true correlation. Adjusting craniofacial relationships for technical error may substantially increase the proportion of variation explained, and thereby alter statistical inferences drawn from results.

Cephalometry↗
PubMed1983

Adult stature and age at menarche in Zapotec-speaking communities in the Valley of Oaxaca, Mexico, in a secular perspective.

Adult stature and the age at menarche among individuals from Zapotec-speaking communities in the Valley of Oaxaca in southern Mexico are considered in a secular perspective. Four sets of observations are utilized: 1) adult stature in males and females from five rural communities; 2) age at menarche in adult women and school girls from a single rural community; 3) earlier studies of adult stature in the Valley of Oaxaca; and 4) estimated stature from long bones excavated in various archaeological sites in the Valley of Oaxaca. There were no significant differences among the five communities for stature; hence, the data were pooled for analysis and comparison. Results of linear regression of stature and stature adjusted for the estimated effects of aging after 30 years of age on year of birth indicate negligible secular changes in either sex. Comparisons with statures from earlier surveys, the earliest dates to 1899, also indicate negligible changes. When adult women are grouped according to age, there are no differences in mean ages at menarche between the older and younger women. Mean age at menarche for the total adult sample is 14.53 +/- 0.08 years, which compares favorably with the probit estimate for school girls, 14.70 +/- 0.32 years. These results thus suggest virtually no secular change in adult size and maturity of the Zapotec-speaking population in the Valley of Oaxaca over the past 80 years. Differences in stature between contemporary populations and estimated statures from long bones from several archaeological sites in Oaxaca are small, and thus suggests little secular change over the past one to two-thousand years.

Adult↗
PubMed1983

A craniofacial growth maturity gradient for males and females between 4 and 16 years of age.

Differential growth of the craniofacial complex implies variation in ontogenetic patterns of development. This investigation quantifies the relative maturity--as defined by percent adult status--of nine cephalometric dimensions and stature. Analysis is based on 663 lateral cephalograms from a mixed longitudinal sample of 26 males and 25 females between 4 and 16 years of age. Graphic comparison of maturity status across the age range shows that variation is intergraded between the neural and somatic growth maturity patterns, as described by head height and stature, respectively. The maturity gradient moves from head height through anterior cranial base, posterior cranial base and maxillary length, upper facial height, corpus length, and ramus height to stature. After 9 years of age ramus height is less mature than stature. Anterior maxillary and mandibular heights diminish during transitional dentition and thereafter exhibit maturity patterns that compare to corpus length. Although females are consistently more mature than males, the gradient of variation between dimensions is sex independent.

Adolescent↗
PubMed1983

Stature, head height, and growth of the vertical face.

Six hundred sixty-three cephalometric radiographs are used in a mixed longitudinal sample of fifty-one subjects (twenty-six males and twenty-five females) in order to determine patterns of vertical facial change during growth and to discern lower, mid-, and upper facial relationships with stature and head height. Results indicate that the absolute growth of the face is similar to the neural pattern and that throughout growth the face is larger among males than among females. However, when facial values are examined relative to stature and head height, the vertical face changes at a rate that resembles statural growth. Moreover, when relative growth values are standardized in order to reduce scaling differences, they indicate that, although relative growth for all three facial measures falls between neural and skeletal values, it is closer to the postcranial pattern of change than to the neural pattern. In addition, relative size of the upper face is highly correlated with relative size of the lower face. It is concluded that stature is of greater importance than head height in the prediction of vertical facial growth.

Adolescent↗
PubMed1983

Craniofacial growth and size patterns during postnatal development.

Patterns of craniofacial growth and size relationships are described for a mixed longitudinal sample of 26 males and 25 females, followed serially from four years of age through adult status. The seven dimensions examined, derived from 663 lateral cephalograms, show differential patterns of negative allometric growth relative to statural increase. Relative growth is greatest for mandibular traits, followed by upper facial and neurocranial traits, respectively. Males exhibit greater relative growth than females. Craniofacial variation residual to allometry follows three independent patterns of association defined by principal component analysis. The components are age and sex independent, suggesting that after proportional changes related to absolute size or scale are controlled for, anterior facial, cranial height, and masticatory associations follow separate but proportionate patterns during growth.

Adolescent↗
PubMed1982

Differential long bone growth of children between two months and eleven years of age.

Diaphyseal lengths of the humerus, radius, femur and tibia of upper-middle class While children between two months and 11 years of age show positive allometric growth, indicating substantial shape or proportional change. The segments of the lower extremity display greater allometric increase than the humerus and radius; variation in relative growth within each extremity is small and inconsistent. Sex differences are consistent, with slightly greater proportional increases demonstrated for boys. The results suggest that absolute intralimb variation in growth, following a disto-proximo growth or maturity gradient, is due to initial differences in size or scale and not to differences in patterns of growth. Developmental variation between extremities is due to scaling plus variation in relative growth patterns.

Aging↗
PubMed1982

Principal components of craniofacial growth for white Philadelphia males and females between 6 and 22 years of age.

Three principal components, explaining 83 percent of the common variation for 999 males and females between 6 and 22 years of age, describe ontogenetic patterns of relationship for seven facial dimensions, including sella-nasion, sella-basion, nasion-prosthion, infradentale-menton, articulare-gnathion, gonion-gnathion, and articulare-gonion. Accounting for 65 percent of the variation, a general component associated with both size and shape defines size-required changes in proprotion during growth. Independent patterns of regional variation associated with alveolar remodeling (second component) and condylar growth (third component) describe specific sources of facial modification. Mean multivariate component scores reveal that sexual dimorphism, which progressively favors males over females with age, results from accumulating differences in size and related proportional changes in shape. The timing of the condylar growth spurt, as evident from variation in ramus height, produces secondary dimorphism which diminishes following the adolescent phase in males. Significant age effects are indicated for alveolar remodeling and mandibular growth of the condyle.

Adolescent↗
PubMed1982

Aging in selected anthropometric dimensions in a rural Zapotec-speaking community in the Valley of Oaxaca, Mexico.

Stature, weight, arm circumference, triceps skinfold and grip strength were measured in a cross-sectional sample of 116 men and 113 women, 20-82 years of age, from a rural Zapotec-speaking community in the Valley of Oaxaca in southern Mexico. Mortality statistics, growth, and maturity status of children in the village are indicative of chronic mild-to-moderate under-nutrition. Adult Zapotecs are smaller, lighter and leaner than reference data for better-off populations. Sex differences are clearly evident for stature, fatness and grip strength. Body weight shows little sex difference after 40 years of age. Estimated mid-arm muscle circumference, however, is larger in males at all ages except over 60 years. Weight, arm circumference, the triceps skinfold and estimated muscle circumference are generally lowest in women 20-39 years, most likely reflecting the depletion of energy stores due to successive pregnancies and lactation. When stature is adjusted for the estimated loss associated with aging, there is suggestion of a secular increase in males but not in females. Sampling variation, small numbers at the older ages, and perhaps selective out migration must be considered in evaluating possible secular effects. Although absolute grip strength of adult Zapotecs is less than that of better-off samples of adults, grip strength per unit body weight is similar.

Adult↗