Lawrence P. Greksa

The dietary adequacy of edentulous older adults

This study tested the null hypothesis that there are no differences in dietary patterns or adequacy between edentulous patients and individuals with nearly complete dentitions. The research design involved comparing the dietary patterns and adequacies of 34 edentulous subjects who regularly wear dentures with 38 subjects who had nearly complete dentitions. The subjects were between the ages of 51 and 83 years and were sampled from patients attending Case Western Reserve University Dental Clinic. Although edentulous subjects were more likely to claim that they had trouble chewing their food, they were not more likely to select easy-to-chew foods. On the other hand, the diet of dentate subjects tended to be superior to that of edentulous subjects, as indicated by a lower fat and cholesterol consumption and a higher consumption of protein and all of the vitamins and minerals (significantly or nearly significantly for vitamin A, ascorbic acid, calcium, and riboflavin).

Effect of altitude on the physical growth of upper-class children of European ancestry

The physical growth of 351 upper-socioeconomic-status children (9-20 years) of European ancestry residing in La Paz, Bolivia (altitude 3600 m) is described and compared with that of lowland children of similar background. The purpose is to evaluate the independent effect of continual exposure to atmospheric hypoxia during the period of growth and development on linear growth. The data presented here indicate that the effect of hypoxia on achieved stature ranges from minimal in males and none in females to a maximum of 3 cm in both sexes. The magnitude of this effect is relatively small compared to the potential effect of other factors which affect the growth of highland children.

Developmental Responses to High-Altitude Hypoxia in Bolivian Children of European Ancestry: A Test of the Developmental Adaptation Hypothesis

The developmental adaptation hypothesis (DAH) proposes that highlanders adapt to their hypobaric hypoxic environment during growth and development. This report utilizes data on children (9.0–19.9 yr) of European ancestry residing in Santa Cruz and La Paz, Bolivia, to test selected aspects of the DAH. Previous tests of this hypothesis have been hampered by difficulties in controlling for socioeconomic and genetic influences. However, due to their high socioeconomic status and their relatively short history of residence at high altitudes, these factors can be reasonably well controlled in studies of European children. The data on European children are consistent with some but not all aspects of the DAH. First, examination of the available data on V̇O2max (ml/kg/min) in European boys suggests that chronic exposure to hypobaric hypoxia results in an enhancement of the overall functional capacity of the oxygen transport system during adolescence, as predicted by the DAH. Second, chronic exposure to hypobaric hypoxia results in a delay in linear growth and maturation in European children, as well as in an enhancement of their lung volumes, also as predicted by the DAH. However, the effects of chronic hypoxia on linear growth, after controlling for health and nutritional status, are not as large as previously believed and, contrary to the expectations of the DAH, they need not be acquired through a distinctive pattern of growth during late childhood and adolescence. Instead, it appears that these patterns are established in European highlanders prior to 9 years of age and are then maintained, rather than accentuated, during later developmental periods.

Age of menarche in Bolivian girls of European and Aymara ancestry

Median age of menarche was determined in children of European and Aymara ancestry residing in La Paz, Bolivia (3600 m) and in children of European ancestry residing in Santa Cruz, Bolivia (400 m). Median age of menarche in European and Aymara highland natives was younger than reported by previous researchers, thus broadening the range of variation in age of menarche in high-altitude populations. Comparisons between La Paz and Santa Cruz European children suggested that growth and development at high altitudes results in a delay in median age of menarche of about 0.8 years.

Population growth and fertility patterns in an Old Order Amish settlement

Background : Since they are a healthy and well-nourished isolate with strong religious proscriptions against birth control, the fertility patterns of the Old Order Amish have long been studied by demographers, particularly those with an interest in natural fertility. Aim : The present report describes population growth, population structure, and fertility patterns in a little-studied Amish settlement located in northeastern Ohio, USA (Geauga Settlement). Subjects and methods : A directory prepared by the Geauga Settlement provides data on the dates of birth of the mother, father, and all children for 1337 families for the period up to 1 January 1993. This information was used to assess population size, population structure, fertility rates, age at marriage, age of mothers at first and last birth, and birth intervals. Estimates of total settlement size were also derived from an older directory covering the period up to 1 January 1988 and a recently published directory which covers the period up to 1 January 1998. Results : The settlement consisted of 7546 individuals in 1988, 8345 individuals in 1993, and 9572 individuals in 1998. The completed marital fertility rate was 7.7 (SD 3.6) births per woman. Total fertility rate decreased by about one birth between 1909 and 1967, in association with a change in fertility patterns, with women born in more recent cohorts tending to have more of their offspring at an earlier age, both of which suggest the existence of behaviours to control fertility. On the other hand, the age at the birth of the last child remained fairly constant over this time period. Conclusions : There is some suggestion of fertility control by Amish families. However, this control appears to be independent of parity, suggesting that there is no intention to limit family size. It is therefore reasonable to conclude that the Amish in the Geauga Settlement are a natural fertility population.

Lung function of young Aymara highlanders

The patterns of development of FVC, FEV and %FEV are examined in 217 male and 195 female youths of Aymara ancestry residing in La Paz, Bolivia (altitude 3600 m). The data provide some evidence of an acceleration in the development of lung function relative to stature in Aymara children, beginning during early adolescence, and also indicate that there is a strong relationship between lung function and chest dimensions in Aymara children. Similar patterns have been observed among Quechua youth. However, despite the general similarity between Quechua and Aymara youths in the development of lung function, there are potentially important differences between them. In particular, the magnitude of the acceleration of lung volumes relative to stature among Aymara children appears to be considerably less than is exhibited by highland Quechua children. In addition, shorter Quechua boys have FVC values similar to those of shorter Aymara boys, despite having significantly larger chests, while taller Quechua boys have considerably larger FVC values than taller Aymara boys, without a corresponding increase in chest size relative to stature. Thus, although lung volumes and chest dimensions are closely related in both groups, the development of lung function to chest size of Quechua boys appears to be somewhat different from that of Aymara boys and, in particular, to be amplified during adolescence in response to factors other than simply an increase in chest size.

Work performance of high-altitude Aymara males.

The sample for this study consisted of 28 Aymara males between the ages of 15 and 43 years. The subjects were rural high-altitude natives who were temporarily working as porters in La Paz, Bolivia (3700 m). Mean VO2max was 46 X 5 ml/kg/min. There was a significant negative relationship between VO2max and age in adult porters . However, there was also a significant positive relationship between maximal work output and age and a significant negative relationship between VO2 during submaximal exercise and age. Relative work intensity (VO2/VO2max) during submaximal exercise did not change significantly with age. Thus, even though VO2max decreased significantly with age, these data suggest that there may not be a substantial decrease with age in the adaptive status of these men. Minimal support was found for the hypothesis that chest size in Andean highlanders influences the effectiveness of the oxygen transport system.

BIRTH SEASONALITY IN THE OLD ORDER AMISH

The Old Order Amish are a healthy and well-nourished natural fertility population, so that the timing of births is not influenced by behaviours to limit family size, undernutrition or disease. The present study examines the monthly distribution of 8160 births occurring between 1920 and 1991 in the Geauga Settlement in north-east Ohio, USA. The monthly distribution of births in the Geauga Settlement is bimodal, with a major peak extending from August to October, a minor peak in February, and a major trough from April to June. This pattern is almost identical to the pattern found in the US in 1943. The monthly distribution of first births appears to be influenced to some extent by a highly significant seasonal pattern of weddings. The pattern of births in the Old Order Amish is consistent with the hypothesis that the spring trough in US births is at least partially caused by a decrease in coital frequency and/or a decrease in fecundability as a result of hot summer temperatures but is not consistent with the hypothesis that the fall peak in US births is primarily due to an increase in coital frequency during the Thanksgiving and Christmas holiday seasons.

Surnames as indicators of European admixture in Andean Indians

The goal of the present report was to determine how well surnames assess the degree of European admixture in urban Aymara. Reflectances, which were measured at three wavelengths (425 nm, 545 nm, and 685 nm) and on two sites (the medial surface of the upper arm and the forehead), were used as genetic markers. The sample consisted of 556 Andean Indians of Aymara ancestry (305 males, 251 females; 10.0–29.9 yr) residing in La Paz, Bolivia (average altitude of about 3600 m). The first component from a principal components analysis was demonstrated to assess the underlying genetics of pigmentation, after controlling for tanning and vascularity, the two primary environmental modifiers of skin color. The scores associated with the first principal component were there-force entered into a discriminant function analysis, which indicated that surnames provide a useful indirect index of the degree of European admixture in urban Aymara. However, these results also suggested that the relationship between, surnames and ethnicity is not equally strong across all surname categories. In particular, the likelihood of correctly predicting surname category from reflectances was about twice that expected by chance alone in individuals with two Aymara or two Spanish surnames but was slightly less than would be expected by chance alone in those with mixed surnames. In addition, the findings of this study suggested that there may be significant genetic differences between rural and urban Aymara.

Anthropometric survey of high-altitude Bolivian porters

This paper presents the results of an anthropometric survey of 138 rural Aymaran high-altitude males who were working as porters in La Paz, Bolivia (3700 m). All subjects were measured for stature, weight, upper arm circumference, and triceps skinfolds. The body size and composition of the porters were then compared to an Aymaran rural population from the Bolivian highlands, and urban mestizo labourers from La Paz. The porters were smaller than the urban sample, but appeared to be generally representative of rural Aymaran natives with respect to body size and composition, and nutritional status. It is suggested that towards one extreme of nutritional variability, some degree of undernutrition may be indicated, which should be considered in future studies of adaptation to hypoxia among these Andean highlanders.