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Biomedical subjects

A R Frisancho

Publications and source records attributed to A R Frisancho.

At least 19 recordsLinked to original sources
PubMed1995

Developmental, genetic, and environmental components of aerobic capacity at high altitude.

The aerobic capacity of 268 subjects (158 males and 110 females) was evaluated in La Paz, Bolivia situated at 3,750 m. The sample included 1) 39 high altitude rural natives (all male); 2) 67 high altitude urban natives (32 male, 35 female); 3) 69 Bolivians of foreign ancestry acclimatized to high altitude since birth (37 male, 32 female); 4) 50 Bolivians of foreign ancestry acclimatized to high altitude during growth (25 male, 25 female); and 5) 42 non-Bolivians of either European or North American ancestry acclimatized to high altitude during adulthood (25 male, 18 female). Data analyses indicate that 1) high altitude urban natives, acclimatized to high altitude since birth or during growth, attained higher aerobic capacity than subjects acclimatized to high altitude during adulthood; 2) age at arrival to high altitude is inversely related to maximum oxygen consumption (VO2 max) expressed in terms L/min or ml/min/kg of lean body mass, but not in terms of ml/min/kg of body weight; 3) among subjects acclimatized to high altitude during growth, approximately 25% of the variability in aerobic capacity can be explained by developmental factors; 4) as inferred from evaluations of skin color reflectance and sibling similarities, approximately 20 to 25% of the variability in aerobic capacity at high altitude can be explained by genetic factors; 5) except among the non-Bolivians acclimatized to high altitude during adulthood, the aerobic capacity of individuals with high occupational activity level is equal to the aerobic capacity of high altitude rural natives; and 6) the relationship between occupational activity level and aerobic capacity is much greater among subjects acclimatized to high altitude before the age of 10 years than afterwards. Together these data suggest that the attainment of normal aerobic capacity at high altitude is related to both developmental acclimatization and genetic factors but its expression is highly mediated by environmental factors, such as occupational activity level and body composition.

Acclimatization↗
PubMed1991

Decreased stature associated with moderate blood lead concentrations in Mexican-American children.

The relationship of blood lead concentration to stature was evaluated by examining data from a sample of 1454 Mexican-American children aged 5-12 y, derived from the data sets of the Hispanic Health and Nutrition Examination Survey (HHANES) conducted in 1982-1984. The results indicate that there is an inverse relationship between blood lead concentration in the range 0.14-1.92 mumol/L with stature. The present finding suggests that growth retardation may be associated even with moderate concentrations of blood lead. Therefore, permissible exposure levels of lead for children deserve reexamination in light of the present analysis.

Age Factors↗
PubMed1988

Origins of differences in hemoglobin concentration between Himalayan and Andean populations.

Mean hemoglobin concentration of 3511 adult males derived from 19 studies of Andean male permanent residents and 10 studies of Himalayan male permanent residents were compared with reference to partial pressure of inspired oxygen. The regression equation (weighted for sample size) of PIO2 and hemoglobin concentration of the Andean miners is significantly (P less than 0.01) greater than that of the Andean and Himalayan non-miners. However, the relationship of PIO2 and Hb is similar in the non-mining Andean and Himalayan samples. These findings suggest that the observed differences in hemoglobin concentration between Andean and Himalayan samples are due, in part, to the inclusion of miners in the Andean samples. The higher barometric pressure associated with the north latitude location of the Himalayans may also contribute to decrease the hypoxic stress in the Himalayas. The present data suggest that Andeans and Himalayans have a similar hemopoietic response to hypoxic stress.

Adult↗
PubMed1987

Standards of arm muscle by stature for the assessment of nutritional status of children.

This study is based on a sample of 9,134 children ranging in age from 2 to 17 years from which the excessively lean and fat children by skinfold thickness were excluded. This sample was derived from the combined data sets of the first and second National Health and Nutrition Examination Surveys (NHANES I and II) of 1971-1974 and 1976-1980. Means and percentiles of upper arm muscle area were calculated for 3 cm increments in stature from 84 to 184 cm for boys and from 84 to 176 cm for girls. Based on means, Z-score units, and percentile ranges of upper arm muscle area by stature, five operational categories of nutritional status have been established. It is recommended that these standards and this classification system be used to supplement current standards of weight for age and weight for height in order to obtain a more complete assessment of body composition and nutritional status.

Adolescent↗
PubMed1985

Developmental and nutritional determinants of pregnancy outcome among teenagers.

To investigate the determinants of low birth weight in infants born to adolescent mothers, we studied the obstetric population attended at the Maternity Hospital of Lima, Peru. From this population, 1256 gravidas, ranging in age from 12 to 25 years, volunteered to participate in this study. Anthropometric and biochemical measurements were used to evaluate the nutritional status and physiological maturity of the mother and newborn. For analytical reasons the young teenaged mothers (less than 15 years) were classified as either still-growing or having completed their growth, depending on their height relative to their parents' height. Similarly, the young teenagers were classified as either gynecologically immature or gynecologically mature depending on whether their gynecological age was less than or greater than 2 years. Our results indicate that young still-growing teenagers, even when matched for nutritional status, have smaller newborns than adult mothers. The data also demonstrate that maternal gynecological age per se does not affect prenatal growth. As inferred from multivariate analyses, it appears that the reduction in birth weight among young teenagers can be explained in part by a decreased net availability of nutrients resulting from the competition for nutrients between the mother's growth needs and the growth needs of her fetus and by an inability of the teenage placenta to maintain placental function adequately for active fetal growth.

Adolescent↗
PubMed1984

Blood pressure in blacks and whites and its relationship to dietary sodium and potassium intake.

The 24-hour dietary intake and blood pressure of 1928 black and 9739 white adults derived from the data sets of the first US National Health and Nutrition Examination Survey (NHANES I) of 1971-1974 were analyzed. Contrary to expectation, the absolute and relative intakes of sodium and potassium in blacks were less than those of whites. However, because the difference in potassium was greater than the difference in sodium, blacks did have a significantly higher sodium/potassium ratio than whites. Blacks had significantly higher blood pressure than whites even when adjusted for differences in sodium/potassium ratio. It is concluded that the higher blood pressure and prevalence of hypertension in blacks does not appear to be a function of an absolutely greater dietary sodium intake, but related to a relatively low intake of potassium. It is possible that blacks have a greater sensitivity than whites to the hypertensinogenic effects of sodium which, coupled with the relatively low dietary intake of potassium, accounts for their increased blood pressure.

Adult↗
PubMed1984

Influence of growth status and placental function on birth weight of infants born to young still-growing teenagers.

To investigate the determinants of fetal maturation of infants born to adolescent mothers, we studied the obstetric population attended at the Maternity Hospital of Lima, Peru. From this population we selected for inclusion in this study a sample of 412 adolescent mothers ranging in age from 13 to 15 yr. These subjects were selected because the anthropometric measurements of their parents were obtained at the time the adolescents were being attended for delivery. Based on the height measurements of the teenagers' mothers and fathers, the adolescents were classified as either still growing or growth completed depending on whether their height was less or greater than their mothers' height. Infants of young adolescent mothers who had not completed their expected growth in height were significantly lighter in birth weight than those born to adolescent mothers who had completed their growth. Multiple regression and path analyses revealed that the effects of weight gain and placenta weight on birth weight were more effective among the infants born to adolescent mothers who had not completed their growth in height. These data suggest that the reduction in birth weight among immature still-growing adolescents may result from both a decreased net availability of nutrients and/or an inability of the placenta to function adequately for active fetal growth, which results in a retarded fetal growth.

Adolescent↗
PubMed1984

New standards of weight and body composition by frame size and height for assessment of nutritional status of adults and the elderly.

The study includes measurements of height, weight, triceps skinfold, subscapular skinfold, upper arm circumference, and elbow breadth of a cross-sectional multiracial sample of 21,752 subjects aged 25 to 74 yr derived from the data sets of the first and second National Health and Nutrition Examination Surveys (NHANES I and NHANES II). Based on these data, percentiles of weight, skinfolds, and bone-free upper arm muscle area by height, sex, and frame size were established for all races combined in two groups: adults aged 25 to 54 yr and the elderly aged 55 to 74 yr. These new standards can be used to differentiate those who are at risk of being obese and undernourished. It is recommended that assessment of anthropometric nutritional status and health status of contemporary adult and elderly populations be made with reference to the present standards in conjunction with age correction factors.

Adult↗
PubMed1983

Elbow breadth as a measure of frame size for US males and females.

Correlation coefficients of weight, bitrochanteric and elbow breadth to the log-transformed skinfold thickness and age were calculated using 16,494 adult Black and white samples derived from the data sets of the US Health and Nutritional Examination Survey I of 1971 to 1974. Among the variables, elbow breadth exhibited the lowest correlation with skinfold thickness and changes little with age. The analysis shows that elbow breadth can be used as an indicator of frame size. Based on sex-, race-, and age-specific percentiles of elbow breadth the subjects were classified into categories of small, medium, and large frame size. It is suggested that these categories be used for the evaluation of weight for height and frame size.

Adolescent↗
PubMed1983

Maternal nutritional status and adolescent pregnancy outcome.

To investigate the determinants of low birth weight of infants born to adolescent mothers, we studied the obstetric population attended at the Maternity Hospital of Lima, Peru. From this population we selected for study a sample of 1256 adolescent mothers ranging in age from 12 to 25 yr. The study included anthropometric and biochemical measurements used to evaluate nutritional status and physiological maturity of the mother and newborn. Findings from the present research indicate that the low birth weight of infants born to adolescent mothers is not due to premature delivery (short gestation) or low gynecological maturity. Furthermore, young adolescent mothers had smaller and thinner newborns than those born to older women who were adjusted for nutritional status during pregnancy and at delivery. That is, despite the similar nutritional status among the young adolescent mothers, the availability of nutrients for the accumulation of calories in the fetus (measured by skinfold thickness) was less than that of older women. Furthermore, the pregnancy weight gain associated with an optimal or average newborn weight is greater for young teenagers than for older women. These findings support the hypothesis that among rapidly growing teenagers the nutritional requirements of pregnancy may be greater than those of older women, and that this increased requirement competes with the growth needs of the fetus.

Adolescent↗
PubMed1983

Perspectives on functional adaptation of the high altitude native.

The major physiological processes that enable humans to attain a complete acclimatization to high altitude are briefly reviewed. The available data indicate that: (a) complete acclimatization to high altitude is associated with changes of environmentally modifiable functional traits such as lung volume but not associated with the expression of genetically controlled features such as chest size; (b) as judged by measurements of maximal aerobic power, the high altitude native has attained at high altitude an adaptation that is comparable to that attained by the low altitude native at sea level; the available information suggests that such adaptation is acquired through growth and development in an hypoxic environment; at present, however, we do not know the developmental modifications that occur within each component of the oxygen transport system, such as ventilation, pulmonary diffusion, and oxygen transport, that enable a sea level native to attain a complete functional adaptation to high altitude; and (c) at comparable altitudes among high altitude natives, there are some inter-regional differences in hemopoietic response, so that the samples derived from mining regions of the Andes are characterized by higher hemoglobin concentration than those derived from non-mining areas or the Himalayas. The source of these differences remains to be investigated.

Adaptation, Physiological↗
PubMed1982

Relative merits of old and new indices of body mass with reference to skinfold thickness.

Correlation coefficients among the various commonly used indices of body mass and measures of skinfold thickness were calculated using 16,459 adult Black of white samples derived from the data sets of the US Health and Nutritional Examination Survey I of 1971 to 1974. Compared to weight and weight-height cube ratio, weight-height square ratio, and weight-heightp ratio exhibit the highest correlation with skinfold thickness. Furthermore, weight-height square ratio and weight-heightp ratio showed the same amount of correlation with skinfolds. Therefore, weight-heightp ratio is not the best indicator of adiposity. It is concluded that weight-height square ratio along with measures of subcutaneous fat such as skinfold thickness would provide adequate information about body size and body fatness. The applicability of weight-heightp is limited to studies concerned with interpopulation comparisons of body mass and where there are differences in height.

Adolescent↗
PubMed1981

Heritability and components of phenotypic expression in skin reflectance of Mestizos from the Peruvian lowlands.

Skin reflectance was measured on the inner arm and forehead of a sample of 209 Mestizos ranging in age from 2 to 64 years living in the town of Lamas in the Eastern peruvian Lowlands. The sample consisted of 43 father-son, 42 father-daughter, 62 mother-son, and 70 mother-daughter pairs. The sample also consisted of 57 brother-brother, 60 sister-sister and 139 brother-sister pairs. The reflectance measurements were made with a Photovolt Reflection Meter, model 670. Stepwise polynomial regression techniques were used to derive standardized residual values. Then using these residual values parent-offspring, sibling intraclass correlations and components of the phenotype expression of skin reflectance were calculated. The study indicates that 1) the parent-offspring and sibling correlation coefficients conformed with the theoretical correlations expected assuming polygenic inheritance; 2) the husband-wife correlations indicate a high degree of assortative mating for skin color, but despite this effect the parent-offspring and sibling correlation coefficients are lower that the values expected under the influence of autosomal genes; 3) estimates of heritability and components of phenotypic expression indicate that about 55% of the total variability in skin reflectance could be attributed to the influence of additive genetic factors; and 4) there is no evidence of X-linkage in the inheritance of skin color.

Adolescent↗