Browsing by Autor "Enrique Vargas"

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A Genomewide Admixture Mapping Panel for Hispanic/Latino Populations
(Elsevier BV, 2007) Xianyun Mao; Abigail W. Bigham; Rui Mei; Gerardo Gutiérrez‐Gutiérrez; Ken Weiss; Tom D. Brutsaert; Fabiola Lèon‐Velarde; Lorna G. Moore; Enrique Vargas; Paul McKeigue
Altered thermal and metabolic control in newborn rats at high altitude
(Wiley, 2008) Vincent Joseph; Jorge Soliz; Max Gassmann; Marcelino Gonzales Isidro; Enrique Vargas; Rudy Soria
In acute hypoxia, newborn reduce oxygen consumption (VO2) and rectal temperature (Tr), but it remains unclear if these responses are maintained in chronic hypoxia. We used rats living at high altitude (3600 m, La Paz Bolivia) at postnatal days 7–8 (P7, n=5, body weight 13±1 g) and 15–16 (P15, n=6, 21±1 g). Tr and VO2 were measured in 21%O2 (room air), 35%O2 (sea level PO2), and 10%O2 (hypoxia), during 20 minutes each. Ambient temperature (Ta) was 34°C at P7 and 30°C at P15. Tr‐Ta was used as an index of thermoregulatory control. At P7, Tr‐Ta was −0.1±0.2°C, suggesting that thermoregulatory control is not established. In 35%O2, Tr was 34.8±0.2°C, and 32.0±0.6°C in 10%O2. At P15, Tr‐Ta was 5.2±0.2°C in room air, Tr did not increased in 35%O2, and was 31.8±0.4°C in 10%O2. VO2 was high (P7=8.6±0.8; P15=9.4±0.4 ml/min/100g) compared to sea level rats (5 ml/min/100g in 20g P10 rats). In P7 and P15 rats, VO2 increased in 35%O2 and dropped in 10%O2. Our results suggest that chronic hypoxia delays the establishment of thermoregulation and increases metabolic rate in newborn rats. The drop of Tr and VO2 in 10%O2 were however well maintained. Founded by NSERC
An Evolutionary Model for Identifying Genetic Adaptation to High Altitude
(Springer Nature, 2007) Lorna G. Moore; Mark D. Shriver; Lynne Bemis; Enrique Vargas
Andean and Tibetan patterns of adaptation to high altitude
(Wiley, 2013) Abigail W. Bigham; Megan J. Wilson; Colleen G. Julian; Melisa Kiyamu; Enrique Vargas; Fabiola Lèon‐Velarde; Maria C. Rivera; Carmelo Rodriquez; Vaughn A. Browne; Esteban J. Parra
These results contribute to our understanding of the unique set of adaptations developed in different highland groups to the hypoxia of high altitude. Overall, the results provide key insights into the patterns of genetic adaptation to high altitude in Andean and Tibetan populations.
Anthropometry and Lung Function of 10- to 12-Year-Old Bolivian Boys
(Thieme Medical Publishers (Germany), 1994) Mercedes Villena; Hilde Spielvogel; Enrique Vargas; Philippe Obert; Ana Alarcón; C. Gonzales; G. Falgairette; H.C.G. Kemper
Anthropometric measurements of 23 HAHSES, 44 HALSES, 43 LAHSES, and 28 LALSES boys (see Introduction to this Supplement) are presented here. They include body height (H), body weight (BW), upper arm circumference (UAC), and skinfold thickness taken at four locations. From these measurements, body fat, lean body mass, and body mass index (BMI = BW/H2) were calculated. The degree of maturation was assessed according to Tanner, orchidometry, and by quantification of testosterone in saliva. Lung function data include: vital capacity (VC), forced expired volume per 1 s (FEV1), functional residual capacity (FRC), residual volume (RV), and total lung capacity (TLC). The results show enhanced lung volumes in both HA groups in comparison to LA groups, with HALSES boys having the greatest increase, even though the LSES boys were significantly smaller compared to the HSES boys at both altitudes and their growth was delayed by approximately 2 years. From the anthropometric data it appears that physical growth of prepubertal boys is dependent on SES but not on high-altitude exposure. We tentatively conclude that chronic hypoxia per se does not affect physical growth in prepubertal boys in an Andean environment and that development of lung function is accelerated in relation to linear growth as has been suggested by other authors (15).
Augmented uterine artery blood flow and oxygen delivery protect Andeans from altitude-associated reductions in fetal growth
(American Physiological Society, 2009) Colleen G. Julian; Megan J. Wilson; M. de la Flor; Henry Yamashiro; Wilma Téllez; Armando Rodríguez; Abigail W. Bigham; Mark D. Shriver; Carmelo Rodriguez; Enrique Vargas
The effect of high altitude on reducing birth weight is markedly less in populations of high- (e.g., Andeans) relative to low-altitude origin (e.g., Europeans). Uterine artery (UA) blood flow is greater during pregnancy in Andeans than Europeans at high altitude; however, it is not clear whether such blood flow differences play a causal role in ancestry-associated variations in fetal growth. We tested the hypothesis that greater UA blood flow contributes to the protection of fetal growth afforded by Andean ancestry by comparing UA blood flow and fetal growth throughout pregnancy in 137 Andean or European residents of low (400 m; European n = 28, Andean n = 23) or high (3,100-4,100 m; European n = 51, Andean n = 35) altitude in Bolivia. Blood flow and fetal biometry were assessed by Doppler ultrasound, and maternal ancestry was confirmed, using a panel of 100 ancestry-informative genetic markers (AIMs). At low altitude, there were no ancestry-related differences in the pregnancy-associated rise in UA blood flow, fetal biometry, or birth weight. At high altitude, Andean infants weighed 253 g more than European infants after controlling for gestational age and other known influences. UA blood flow and O(2) delivery were twofold greater at 20 wk in Andean than European women at high altitude, and were paralleled by greater fetal size. Moreover, variation in the proportion of Indigenous American ancestry among individual women was positively associated with UA diameter, blood flow, O(2) delivery, and fetal head circumference. We concluded that greater UA blood flow protects against hypoxia-associated reductions in fetal growth, consistent with the hypothesis that genetic factors enabled Andeans to achieve a greater pregnancy-associated rise in UA blood flow and O(2) delivery than European women at high altitude.
Comparative Aspects of High-Altitude Adaptation in Human Populations
(Springer Nature, 2002) Lorna G. Moore; V. Fernando Armaza; Mercedes Villena; Enrique Vargas
Determinants of blood oxygenation during pregnancy in Andean and European residents of high altitude
(American Physiological Society, 2007) Marco Antonio Paco Vargas; Enrique Vargas; Colleen G. Julian; J. Fernando Armaza; Armando Rodríguez; Wilma Téllez; Susan Niermeyer; Megan Wilson; Esteban J. Parra; Mark D. Shriver
High altitude decreases birth weight, but this effect is diminished in long vs. short-resident, high-altitude populations. We asked whether women from long vs. short-resident, high-altitude populations had higher arterial oxygenation levels by comparing 42 Andean and 26 European residents of La Paz, Bolivia (3,600 m), serially during pregnancy (weeks 20, 30, and 36) and again 4 mo postpartum. Pregnancy raised hypoxic ventilatory sensitivity threefold, resting ventilation (.Ve), and arterial O(2) saturation (Sa(O2)) in both groups. Ancestry, as identified using 81 genetic markers, correlated with respiratory pattern, such that greater Andean ancestry was associated with higher respiratory frequency and lower tidal volume. Pregnancy increased total blood and plasma volume approximately 40% in both groups without changing red blood cell mass relative to body weight; hence, hemoglobin fell. The hemoglobin decline was compensated for by the rise in .Ve and Sa(O2) with the result that arterial O2 content (Ca(O2)) was maintained near nonpregnant levels in both groups. Birth weights were similar for all Andean and European babies, but after adjusting for variation in gestational age, maternal height and parity, Andeans weighed 209 g more than Europeans. Babies with heavier birth weights and greater ponderal indices were born to Andean women with higher Ve during pregnancy. We concluded that while maternal .Ve and arterial oxygenation were important, some factor other than higher Ca(O2) was responsible for protecting Andeans from altitude-associated reductions in fetal growth.
Developmental components of resting ventilation among high- and low-altitude Andean children and adults
(Wiley, 1999) A. Roberto Frisancho; Patricia Juliao; Veronica Barcelona; Carmela E. Kudyba; Glenda Amayo; Grecia Davenport; Alicia Knowles; Dani Sanchez; Mercedes Villena; Enrique Vargas
This paper evaluates the age-associated changes of resting ventilation of 115 high- and low-altitude Aymara subjects, of whom 61 were from the rural Aymara village of Ventilla situated at an average altitude of 4,200 m and 54 from the rural village of Caranavi situated at an average altitude of 900 m. Comparison of the age patterns of resting ventilation suggests the following conclusions: 1) the resting ventilation (ml/kg/min) of high-altitude natives is markedly higher than that of low-altitude natives; 2) the age decline of ventilation is similar in both lowlanders and highlanders, but the starting point and therefore the age decline are much higher at high altitude; 3) the resting ventilation that characterizes high-altitude Andean natives is developmentally expressed in the same manner as it is at low altitude; and 4) the resting ventilation (ml/kg/min) of Aymara high-altitude natives is between 40-80% lower than that of Tibetans.
Developmental components of resting ventilation among high‐ and low‐altitude Andean children and adults
(Wiley, 1999) A. Roberto Frisancho; Patricia Juliao; Veronica Barcelona; Carmela E. Kudyba; Glenda Amayo; Grecia Davenport; Alicia Knowles; Dani Sanchez; Mercedes Villena; Enrique Vargas
This paper evaluates the age-associated changes of resting ventilation of 115 high- and low-altitude Aymara subjects, of whom 61 were from the rural Aymara village of Ventilla situated at an average altitude of 4,200 m and 54 from the rural village of Caranavi situated at an average altitude of 900 m. Comparison of the age patterns of resting ventilation suggests the following conclusions: 1) the resting ventilation (ml/kg/min) of high-altitude natives is markedly higher than that of low-altitude natives; 2) the age decline of ventilation is similar in both lowlanders and highlanders, but the starting point and therefore the age decline are much higher at high altitude; 3) the resting ventilation that characterizes high-altitude Andean natives is developmentally expressed in the same manner as it is at low altitude; and 4) the resting ventilation (ml/kg/min) of Aymara high-altitude natives is between 40–80% lower than that of Tibetans. Am J Phys Anthropol 109:295–301, 1999. © 1999 Wiley-Liss, Inc.
Developmental, genetic, and environmental components of aerobic capacity at high altitude
(Wiley, 1995) A. Roberto Frisancho; Hedy G. Frisancho; Mark Milotich; Tom D. Brutsaert; Rachel Albalak; Hilde Spielvogel; Mercedez Villena; Enrique Vargas; Rudy Soria
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.
Developmental, genetic, and environmental components of lung volumes at high altitude
(Wiley, 1997) A. Roberto Frisancho; Hedy G. Frisancho; Rachel Albalak; Mercedes Villain; Enrique Vargas; Rudy Soria
Vital capacity and residual lung volume (in terms of 1/min or ml/m<sup>2</sup> of body surface area) of 357 subjects (205 males, 152 females) was evaluated in La Paz, Bolivia, situated at 3,750 m. The sample included: (1) 37 high altitude rural natives (all male), (2) 125 high altitude urban natives (69 male, 58 female), (3) 85 Bolivians of foreign ancestry acclimatized to high altitude since birth (40 male, 45 female), (4) 63 Bolivians of foreign ancestry acclimatized to high altitude during growth (30 male, 33 female), and (5) 47 non-Bolivians of either European or North American ancestry acclimatized to high altitude during adulthood (24 male, 23 female). Results indicate that (1) all samples studied, irrespective of origin or acclimatization status, have larger lung volumes than those predicted from sea level norms; (2) the high altitude rural natives have significantly greater lung volumes (vital capacity and residual lung volume) than the high altitude urban natives and all the non-native high altitude samples; (3) males acclimatized to high altitude since birth or during growth attain similar lung volumes as high altitude urban natives and higher residual lung volumes than subjects acclimatized to high altitude during adulthood but lower than the high altitude rural natives; (4) females acclimatized to high altitude since birth or during growth attain similar lung volumes as subjects acclimatized to high altitude during adulthood; (5) age at arrival to high altitude is inversely related to residual lung volume but not vital capacity; (6) among subjects acclimatized to high altitude during growth, approximately 20-25% of the variability in residual lung volume can be explained by developmental factors; (7) among high altitude rural and urban natives, it appears that approximately 20-25% of the variability in residual lung volume at high altitude can be explained by genetic traits associated with skin reflectance and genetic traits shared by siblings; and (8) vital capacity, but not the residual lung volume, is inversely related to occupational activity level. Together these data suggest that the attainment of vital capacity at high altitude is influenced more by environmental factors, such as occupational activity level, and body composition than developmental acclimatization. On the other hand, the attainment of an enlarged residual volume is related to both developmental acclimatization and genetic factors. Am. J. Hum. Biol. 9:191-203, 1997. © 1997 Wiley-Liss, Inc.
Do Anti-angiogenic or Angiogenic Factors Contribute to the Protection of Birth Weight at High Altitude Afforded by Andean Ancestry?
(Springer Nature, 2010) R. Daniela Dávila; Colleen G. Julian; Megan J. Wilson; Vaughn A. Browne; Carmelo Rodriguez; Abigail W. Bigham; Mark D. Shriver; Enrique Vargas; Lorna G. Moore
Do Cytokines Contribute to the Andean-Associated Protection From Reduced Fetal Growth at High Altitude?
(Springer Nature, 2010) R. Daniela Dávila; Colleen G. Julian; Megan J. Wilson; Vaughn A. Browne; Carmelo Rodriguez; Abigail W. Bigham; Mark D. Shriver; Enrique Vargas; Lorna G. Moore
Does Arterial PCO2 Interfere with Hypoxia in Muscular Metabolism in Man?
(Springer Nature, 1990) J Raynaud; Enrique Vargas; M. Sant; J Bordachar; P. Escourrou; O. Bailliart; P Legros; J. Durand
Does chronic mountain sickness (CMS) have perinatal origins?
(Elsevier BV, 2007) Lorna G. Moore; Susan Niermeyer; Enrique Vargas
Effects of Hypoxia and Hyperoxia of Short Duration on the Pulmonary Circulation of Highlanders (HL) and Lowlanders (LL) Living at 3,750 m
(2015) J Coudert; M Paz-Zamora; G Antezana; Enrique Vargas; L. Brian�on
Erythropoietin and Soluble Erythropoietin Receptor: A Role for Maternal Vascular Adaptation to High-Altitude Pregnancy
(Oxford University Press, 2016) Gabriel H. Wolfson; Enrique Vargas; Vaughn A. Browne; Lorna G. Moore; Colleen G. Julian
Our findings suggest that an augmented pregnancy-associated rise in Epo may be important for successful vascular adaptation to pregnancy at HA. We further speculate that the elevated sEpoR observed in PreE vs controls at HA impedes the effect of Epo to maintain endothelial function and may, in turn, be of pathological relevance for PreE at HA.
Evidence that parent‐of‐origin affects birth‐weight reductions at high altitude
(Wiley, 2008) Adam Bennett; Stephen R. Sain; Enrique Vargas; Lorna G. Moore
Hypoxia exerts a profound depressant effect on fetal growth, lowering birth weight, and raising mortality risk. Multigenerational high-altitude populations are relatively protected from this birth-weight decline, leading us to hypothesize that genetic factors were involved. We asked if the amount of high- versus low-altitude ancestry influenced birth weight at high altitude and, specifically, whether such influences were affected by parent-of-origin effects (i.e., genomic imprinting). Medical records were reviewed from 1,343 consecutive, singleton deliveries in La Paz, Bolivia (3,600 m) of high- (Andean) or low- (European) altitude ancestry. Parental surnames were used to classify ancestry as Andean, European, Mestizo ("mixed") or some combination thereof. The effects of population ancestry on birth weight were determined by categorical, conditional linear regression. Babies born at altitude with two Andean parents weighed 252 g more than their European counterparts, with the protective effect being proportional to the amount of Andean parentage and independent of maternal parity, body size, smoking, or socioeconomic status. Paternal compared with maternal transmission raised birth weight 81 g for a given ancestry group. We concluded that indigenous high-altitude ancestry protected against hypoxia-associated fetal growth reduction in a dose-dependent fashion consistent with the involvement of genetic factors. Further, some of the genes involved appeared to be influenced by parent-of-origin effects, given that maternal transmission restricted and paternal transmission enhanced fetal growth.
Graduated effects of high-altitude hypoxia and highland ancestry on birth size
(Springer Nature, 2013) Rudy Soria; Colleen G. Julian; Enrique Vargas; Lorna G. Moore; Dino A. Giussani