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Biomedical subjects

L P Greksa

Publications and source records attributed to L P Greksa.

At least 19 recordsLinked to original sources
PubMed1999

Morbidity and mortality patterns, health beliefs, and health risk factors of Karen highlanders of northwest Thailand.

Morbidity and mortality patterns, health care practices, and health care beliefs were assessed over three seasons in Pwo and Sgaw Karen preschool children living in the highlands of northwest Thailand. The sample consisted of all preschool children from 77 Pwo and 71 Sgaw households. Although the Pwo and Sgaw Karen residing in the highlands of northwest Thailand live in isolated villages in the same ecozone, utilize similar technologies, have similar access to health facilities, and maintain a certain level of sociocultural homogeneity through their identification as Karen, Pwo preschool children exhibit significantly higher levels of morbidity and mortality than their Sgaw counterparts. It is argued that these differences in morbidity and mortality are primarily the function of historical patterns which resulted in an earlier contact of the Sgaw with modem societies and particularly with an earlier exposure to western health care.

Adult↗
PubMed1998

Comparison of skin reflectances between Bolivian lowlanders and highlanders of European ancestry.

I compared one genetic marker, skin reflectances, between Bolivians of European ancestry residing at high altitude in La Paz (3600 m; 41 boys and 65 girls) and at low altitude in Santa Cruz (400 m; 140 boys and 117 girls). Reflectances were measured at three wavelengths (425 nm, 545 nm, and 685 nm) on two different sites: the medial surface of the inner upper arm and the forehead. Principal components analysis was used to reduce age-, sex-, and surname-standardized reflectances to three independent components. The first principal component, which assesses the genetic component of melanin concentration, did not differ between samples, indicating that there are no significant differences between lowland and highland Bolivians of European ancestry with respect to the genetic component of skin reflectances. The second principal component, which assesses the influence of tanning on skin reflectance, also did not differ significantly between highlanders and lowlanders. Finally, the third principal component, which assesses the impact of vascularity on skin reflectance, was significantly lower in residents of La Paz than in residents of Santa Cruz, suggesting a greater vascularity-induced darkening of skin color in highlanders than lowlanders, possibly reflecting the higher hemoglobin concentrations that are typical of highland populations.

Acclimatization↗
PubMed1996

Evidence for a genetic basis to the enhanced total lung capacity of Andean highlanders.

The hypothesis that the enlarged lung volume of Andean highlanders has an important genetic basis was tested in a sample of 203 males and 166 females (10.0-29.9 years old) of Aymara ancestry who were residing in La Paz, Bolivia (3600 m). The measures of lung function included total lung capacity and its components, and skin reflectances were used as genetic markers. Examination of the relationships between each lung volume and skin reflectance and comparisons between skin color categories suggested that an increasing proportion of Aymara genes is associated with progressive increases in lung volume, which is consistent with the hypothesis that the enhanced lung volume of Andean highlanders is to some important extent influenced by genes. Because a previous analysis of the same sample indicated that the enhanced lung volume of Andean highlanders is also partly due to exposure to hypobaric hypoxia during the period of growth and development, it can be concluded that the enhanced lung volume is influenced by both environmental and genetic factors.

Adolescent↗
PubMed1995

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).

Aged↗
PubMed1994

Total lung capacity in young highlanders of Aymara ancestry.

Total lung capacity (TLC) and its components, including residual volume (RV) and vital capacity (VC), are described in a sample of 164 male and 143 female youths of Aymara ancestry (10.0-19.9 years) who were born and raised at high altitudes (> 2,500 m) and who were residing in La Paz, Bolivia (average altitude of about 3,600 m). The hypothesis was tested that the enhanced lung volumes of adult highlanders are attained during the period of growth and development. As found in adult male highlanders, TLC in young highlanders was significantly larger than in lowlanders of the same sex and body size, primarily as a result of increases in RV and secondarily through increases in VC. In addition, estimates of the magnitude of the effect of chronic hypobaric hypoxia on all of the measures of pulmonary function, including TLC, RV, and VC, were positively related to age. This finding suggests that growth and development at high altitude is associated with a constant increase in TLC and other measures of pulmonary function relative to those of lowlanders, a finding which is consistent with the expectations of the developmental adaptation hypothesis. However, although these relationships were statistically significant in males, they were not significant in females. Thus, although the magnitude of the estimated effects of chronic hypobaric hypoxia on TLC, RV, and VC were similar in males and females, the developmental pattern by which these enhanced volumes are achieved may differ between sexes.

Adolescent↗
PubMed1988

Effect of altitude on the lung function of high altitude residents of European ancestry.

The forced vital capacity (FVC), forced expiratory volume in one second (FEV), and ratio of FEV to FVC (%FEV) of 161 male and 158 female youths of European ancestry who were born at high altitudes and who were residing in La Paz, Bolivia (average altitude of 3,600 m) were examined and compared with those for lowland Europeans and highland Aymara Amerindians. FVC and FEV were significantly larger (p less than .001) in the La Paz Europeans than in two lowland control samples of European ancestry, with the relative differences between samples varying from small (1.5-4.1%) to moderate (7.7-11.9%). It could not be determined whether the enhanced lung volumes of the La Paz European children were acquired through an accelerated development of lung volumes relative to stature during adolescence, as is the case for Amerindian highlanders. After controlling for body and chest size, FVC and FEV were significantly smaller in the La Paz Europeans than in highland Aymara (p less than .001), suggesting that the lung volumes of the Aymara are influenced by factors other than simply growth and development at high altitude. Finally, as found in Amerindians, chest size is an important determinant of intra-individual variation in lung function among highland Europeans.

Adolescent↗
PubMed1985

Maximal exercise capacity in adolescent European and Amerindian high-altitude natives.

Forty-seven highland natives were given maximal exercise tests on a treadmill ergometer at 3,600 m. The subjects were grouped into four subsamples on the basis of ethnicity (European vs. Aymara) and age (young vs. old adolescent). Two-way ANOVA indicated that VO2max adjusted for body size did not differ significantly between ethnic groups but was significantly larger in older than younger boys within each ethnic group (p less than .05). This finding does not support the hypothesis that Amerindian highland natives have adapted genetically to hypoxia but is consistent with the hypothesis that the relatively high VO2max's of highlanders are acquired by developmental adaptation. Several measures of ventilation and oxygen transport capacity differed significantly between ethnic groups, suggesting that growing European and Aymara boys may respond somewhat differently to the stress of high-altitude hypoxia. However, despite these differences, VO2max, an integrated measure of the overall functional capacity of the oxygen transport system, did not differ significantly between ethnic groups, suggesting that both groups are equally capable of meeting the body's oxygen requirements during maximal exercise at high altitude.

Adolescent↗
PubMed1984

The physical growth of urban children at high altitude.

The physical growth of urban Aymara children residing in La Paz, Bolivia (3,600 m) is described and compared with Amerindian children residing at low and high altitudes and with low-altitude U.S. children. The sample consists of 227 males (10.6-19.7 yr) and 219 females (11.2-19.8 yr). The urban La Paz children were taller at all ages than rural high altitude Amerindian children but similar in stature to urban high altitude children from Peru. The variation in stature among the high altitude populations was considerable, amounting to average differences between the tallest and shortest samples of about 10 cm in males and 8 cm in females. In addition, stature in the two urban high altitude samples was similar to that of rural low-altitude Amerindians. This overlapping of the distributions of stature in high- and low-altitude populations could easily confound comparisons designed to determine the effects of hypoxia on physical growth. La Paz Aymara children had considerably smaller chest sizes relative to stature than high-altitude Quechua children. However, the available data indicates that relative chest sizes are similar in Aymara and Quechua adults, suggesting that the process by which large chests are achieved may differ between these Andean populations.

Adolescent↗
PubMedDate not supplied

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.

Adult↗
PubMedDate not supplied

Maximal aerobic power in trained youths at high altitude.

The sample for this study consisted of 25 males and 19 females between the ages of 8.8 and 19.5 years. The subjects were healthy, well nourished and trained swimmers residing in La Paz, Bolivia (mean altitude 3700 m). The purpose of this study was to provide normative values for the work capacity of high-altitude youths. Mean VO2 max was 46.9 ml/kg/min in males and 39.3 ml/kg/min in females. VO2max increased significantly with age in males but not in females. Mean VO2max tended to be 10-20% lower in the swimmers than in sea-level athletes.

Adolescent↗