Browsing by Autor "Mercedes Villena"

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Acute and Chronic Altitude-Induced Cognitive Dysfunction in Children and Adolescents
(Elsevier BV, 2015) Stefano F. Rimoldi; Emrush Rexhaj; Hervé Duplain; Sébastien Urben; Joël Billieux; Yves Allemann; Catherine Romero; Alejandro Ayaviri; Carlos E. Salinas; Mercedes Villena
Adrenocortical Suppression in Highland Chick Embryos Is Restored during Incubation at Sea Level
(Mary Ann Liebert, Inc., 2011) Carlos E. Salinas; Mercedes Villena; Carlos E. Blanco; Dino A. Giussani
By combining the chick embryo model with incubation at high altitude, this study tested the hypothesis that development at high altitude is related to a fetal origin of adrenocortical but not adrenomedullary suppression and that hypoxia is the mechanism underlying the relationship. Fertilized eggs from sea-level or high altitude hens were incubated at sea level or high altitude. Fertilized eggs from sea-level hens were also incubated at altitude with oxygen supplementation. At day 20 of incubation, embryonic blood was taken for measurement of plasma corticotropin, corticosterone, and Po(2). Following biometry, the adrenal glands were collected and frozen for measurement of catecholamine content. Development of chick embryos at high altitude led to pronounced adrenocortical blunting, but an increase in adrenal catecholamine content. These effects were similar whether the fertilized eggs were laid by sea-level or high altitude hens. The effects of high altitude on the stress axes were completely prevented by incubation at high altitude with oxygen supplementation. When chick embryos from high altitude hens were incubated at sea level, plasma hormones and adrenal catecholamine content were partially restored toward levels measured in sea-level chick embryos. There was a significant correlation between adrenocortical blunting and elevated adrenal catecholamine content with both asymmetric growth restriction and fetal hypoxia. The data support the hypothesis tested and provide evidence to isolate the direct contribution of developmental hypoxia to alterations in the stress system.
Altitude Related Changes in Red Blood Cell Membrane Lipids and Proteins. Possible Links with Redox Equilibrium, Acid Base Status and Cell Calcium
(2002) Claus Behn; Manuel Estrada; Eliseo Hibert Dávila; Oscar F. Araneda; Max Aguirre González; A. Carrasco; Rudy Soria; Mauricio Araos; Mercedes Villena; Wilma Téllez
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).
Antioxidant intake among maladapted highlanders: link to vascular function
(Cambridge University Press, 2017) Teresa Filipponi; Christopher J. Marley; Julien V. Brugniaux; Carla Murillo Jáuregui; Mercedes Villena; Cláudio Sartori; Stefano F. Rimoldi; Urs Scherrer; Damian M. Bailey
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Apolipoprotein E/C1/C4/C2 Gene Cluster Diversity in Two Native Andean Populations: Aymaras and Quechuas
(Wiley, 2012) Magdalena Gayà‐Vidal; Georgios Athanasiadis; Robert Carreras‐Torres; Marc Vía; Esther Esteban; Mercedes Villena; René Vásquez; Jean‐Michel Dugoujon; Pedro Moral
Summary The APOE/C1/C4/C2 gene cluster presents high relevance in lipid metabolism and, therefore, has important epidemiological implications. Here, we study for the first time the variation patterns of 25 polymorphisms (10 short tandem repeats, STRs, and 15 single nucleotide polymorphismas, SNPs) in two native Andean samples from Bolivia (45 Aymaras and 45 Quechuas) as well as one European sample (n = 41) as external reference. We estimated diversity parameters, linkage disequilibrium patterns, population structure, and possible selective effects. In general, diversity was low and could be partly attributed to selection (probably due to its physiological importance), since the APOE/C1/C4/C2 region was highly conserved compared to the flanking genes in both Bolivians and Europeans. Moreover, the lower gene diversity in Bolivians compared to Europeans for some markers might indicate different demographic histories. Regarding the APOE isoforms, in addition to ɛ3 (94%) and ɛ4 (5%), isoform ɛ2 (1%) was also detected in Bolivians. In relation to previous hypotheses, our results support that genetic drift or founder effects rather than selection for increased cholesterol absorption are the main factors that have shaped the distribution of APOE isoforms observed in South America.
Autosomal and X chromosome <i>Alu</i> insertions in Bolivian Aymaras and Quechuas: Two languages and one genetic pool
(Wiley, 2009) Magdalena Gayà‐Vidal; Jean‐Michel Dugoujon; Esther Esteban; Georgios Athanasiadis; Armando Rodríguez; Mercedes Villena; René Vásquez; Pedro Moral
Thirty-two polymorphic Alu insertions (18 autosomal and 14 from the X chromosome) were studied in 192 individuals from two Amerindian populations of the Bolivian Altiplano (Aymara and Quechua speakers: the two main Andean linguistic groups), to provide relevant information about their genetic relationships and demographic processes. The main objective was to determine from genetic data whether the expansion of the Quechua language into Bolivia could be associated with demographic (Inca migration of Quechua-speakers from Peru into Bolivia) or cultural (language imposition by the Inca Empire) processes. Allele frequencies were used to assess the genetic relationships between these two linguistic groups. Our results indicated that the two Bolivian samples showed a high genetic similarity for both sets of markers and were clearly differentiated from the two Peruvian Quechua samples available in the literature. Additionally, our data were compared with the available literature to determine the genetic and linguistic structure, and East-West differentiation in South America. The close genetic relationship between the two Bolivian samples and their differentiation from the Quechua-speakers from Peru suggests that the Quechua language expansion in Bolivia took place without any important demographic contribution. Moreover, no clear geographical or linguistic structure was found for the Alu variation among South Amerindians.
Cardiac and vascular disease prior to hatching in chick embryos incubated at high altitude
(Cambridge University Press, 2009) Carlos E. Salinas; C. E. Blanco; Mercedes Villena; Emily J. Camm; J. D. Tuckett; Ruwan Weerakkody; Andrew D. Kane; A.M. Shelley; F. B. P. Wooding; Mai Trinh Quy
The partial contributions of reductions in fetal nutrition and oxygenation to slow fetal growth and a developmental origin of cardiovascular disease remain unclear. By combining high altitude with the chick embryo model, we have previously isolated the direct effects of high-altitude hypoxia on growth. This study isolated the direct effects of high-altitude hypoxia on cardiovascular development. Fertilized eggs from sea-level or high-altitude hens were incubated at sea level or high altitude. Fertilized eggs from sea-level hens were also incubated at high altitude with oxygen supplementation. High altitude promoted embryonic growth restriction, cardiomegaly and aortic wall thickening, effects which could be prevented by incubating eggs from high-altitude hens at sea level or by incubating eggs from sea-level hens at high altitude with oxygen supplementation. Embryos from high-altitude hens showed reduced effects of altitude incubation on growth restriction but not on cardiovascular remodeling. The data show that: (1) high-altitude hypoxia promotes embryonic cardiac and vascular disease already evident prior to hatching and that this is associated with growth restriction; (2) the effects can be prevented by increased oxygenation; and (3) the effects are different in embryos from sea-level or high-altitude hens.
Comparative Aspects of High-Altitude Adaptation in Human Populations
(Springer Nature, 2002) Lorna G. Moore; V. Fernando Armaza; Mercedes Villena; Enrique Vargas
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.
Exaggerated exercise‐induced pulmonary hypertension in Chronic Mountain Sickness
(Wiley, 2007) Jonathan Bloch; Thomas Stüber; Marcos Schwab; Pierre‐Yves Jayet; Sébastien Thalmann; Hilde Spielvogel; Carlos E Salinas Salmón; Mercedes Villena; Yves Allemann; Cláudio Sartori
Excessive erythrocytosis is a hallmark of Chronic Mountain Sickness (CMS). By scavenging nitric oxide (NO), erythrocytosis may impair NO bioavailability, and, in turn, increase pulmonary artery tone. Little is known, however, about pulmonary vasoregulation at rest and during exercise in CMS. We measured systolic pulmonary artery pressure (echocardiography) at rest and during exercise (bicycle ergometer) in 20 male subjects with CMS (primary erythrocytosis, Hb level >20g/dl) and 40 healthy controls in La Paz (3600 m). All subjects were Bolivian high‐altitude natives. Hemoglobin levels, as expected, were markedly higher in CMS than in control subjects (22.1±2.0 vs. 16.7±0.8, mean±SD, p<0.001), and were associated with an increased resting systolic pulmonary artery pressure (35.5±8.7 vs. 29.5±4.9 mm Hg, p<0.002). Most importantly, the exercise‐induced increase in pulmonary artery pressure was roughly twice as large in patients with CMS than in control subjects: at 50 Watts systolic‐pulmonary artery pressure increased to 59.3±14.5 mm Hg in the patients, but to only 43.3±8.3 mm Hg in the control subjects (P<0.001). These data provide the first evidence for a strikingly exaggerated pulmonary artery pressure response to mild exercise in CMS. This exaggerated pulmonary vasoconstrictor response, which is possibly related to impaired NO biodisponibility, may contribute to impaired exercise tolerance in CMS.
Exaggerated exercise‐induced pulmonary vasoconstriction in reentry pulmonary edema‐prone subjects and in offspring of preeclampsia
(Wiley, 2007) Cláudio Sartori; Thomas Stüber; Marcos Schwab; Pierre‐Yves Jayet; Jonathan Bloch; Sébastien Thalmann; Hilde Spielvogel; Carlos E. Salinas; Mercedes Villena; Urs Scherrer
Offspring of mothers suffering from preeclampsia and subjects with a history of reentry high‐altitude pulmonary edema (re‐entry HAPE) display sustained hypoxic pulmonary hypertension when living at high altitude and a predisposition to pulmonary edema. The underlying mechanisms are unknown. We hypothesized that the predisposition to pulmonary edema could be caused by capillary stress failure related to exaggerated pulmonary hypertension. We, therefore, estimated the pulmonary artery pressure response (Doppler echocardiography) to mild exercise in 18 re‐entry HAPE‐prone subjects, 12 offspring of preeclampsia and 29 controls, all born and living in La Paz, Bolivia (3600 m). As expected, mean±SD systolic pulmonary artery pressure at rest was higher in re‐entry HAPE prone subjects and offspring of preeclampsia than in controls (42±7 and 37±8 vs. 30±7 mm Hg, P<0.001). Most importantly, the exercise‐induced increase in pulmonary artery pressure was 50 percent larger in the two groups of subjects at risk than in controls (21±8 and 21±10 vs. 14±7 mm Hg, P=0.02). These data provide the first evidence for a markedly exaggerated pulmonary vasoconstrictor response to exercise in high altitude dwellers known to have an augmented susceptibility to develop pulmonary edema. We speculate that this exaggerated response may predispose them to pulmonary edema by causing capillary stress failure.
Exaggerated Pulmonary Hypertension and Right Ventricular Dysfunction in High-Altitude Dwellers With Patent Foramen Ovale
(Elsevier BV, 2014) Roman Brenner; Lorenza Pratali; Stefano F. Rimoldi; Carla Ximena Murillo Jauregui; Rodrigo Soria; Emrush Rexhaj; Carlos Salinas Salmón; Mercedes Villena; Catherine Romero; Cláudio Sartori
Exaggerated Pulmonary Hypertension During Mild Exercise in Chronic Mountain Sickness
(Elsevier BV, 2009) Thomas Stüber; Cláudio Sartori; Marcos Schwab; Pierre‐Yves Jayet; Stefano F. Rimoldi; Sophie Garcin; Sébastien Thalmann; Hilde Spielvogel; Carlos Salinas Salmón; Mercedes Villena
Exercise Induces Rapid Interstitial Lung Water Accumulation in Patients With Chronic Mountain Sickness
(Elsevier BV, 2011) Lorenza Pratali; Stefano F. Rimoldi; Emrush Rexhaj; Damian Hutter; Francesco Faita; Carlos Salinas Salmón; Mercedes Villena; Rosa Sicari; Eugenio Picano; Yves Allemann
Genetic Variations in the TP53 Pathway in Native Americans Strongly Suggest Adaptation to the High Altitudes of the Andes
(Public Library of Science, 2015) Vanessa Cristina Jacovas; Diego Luiz Rovaris; Orlando J. Pérez; Soledad de Azevedo; Gabriel S. Macedo; José R. Sandoval; Alberto Salazar‐Granara; Mercedes Villena; Jean‐Michel Dugoujon; Rafael Bisso‐Machado
The diversity of the five single nucleotide polymorphisms located in genes of the TP53 pathway (TP53, rs1042522; MDM2, rs2279744; MDM4, rs1563828; USP7, rs1529916; and LIF, rs929271) were studied in a total of 282 individuals belonging to Quechua, Aymara, Chivay, Cabanaconde, Yanke, Taquile, Amantani, Anapia, Uros, Guarani Ñandeva, and Guarani Kaiowá populations, characterized as Native American or as having a high level (> 90%) of Native American ancestry. In addition, published data pertaining to 100 persons from five other Native American populations (Surui, Karitiana, Maya, Pima, and Piapoco) were analyzed. The populations were classified as living in high altitude (≥ 2,500 m) or in lowlands (< 2,500 m). Our analyses revealed that alleles USP7-G, LIF-T, and MDM2-T showed significant evidence that they were selected for in relation to harsh environmental variables related to high altitudes. Our results show for the first time that alleles of classical TP53 network genes have been evolutionary co-opted for the successful human colonization of the Andes.
Helping patterns and reproductive success in Aymara communities
(Wiley, 2002) Émile Crognier; Mercedes Villena; Enrique Vargas
"Helpers at the nest," young adults remaining in their parents home to take care of younger siblings, are known in many species of birds and mammals. Similar behaviors are occasionally observed in human societies but their frequency and significance for parental reproductive success are still not fully appraised. This study was designed to document this issue in a traditional Aymara peasant society of the Bolivian Altiplano, It is based on 359 reproductive life histories of women 45 years of age or older and on a survey of children's workload in 1998 and 1999. The presence of "potential helpers" in the household is significantly associated with higher fertility and with improved survival of siblings to sexual maturity. Caretaking is not particularly assigned to older daughters. The positive relationship between the availability of offspring help and reproductive success does not demonstrate a causal role for child caretaking because, in contrast with nonhuman helpers, workloads of children range from housekeeping to agricultural tasks, instead of being focused on feeding or protecting younger siblings. Correlation and multiple regression analyses, however, suggest that the total amount of care given by the older offspring and the amount of care received by each recipient are, along with offspring contribution to household economy, among the determinants of parental reproductive success.
Hemoglobin concentration of high‐altitude Tibetans and Bolivian Aymara
(Wiley, 1998) Cynthia M. Beall; Gary M. Brittenham; Kingman P. Strohl; John Blangero; Sarah Williams‐Blangero; Melvyn C. Goldstein; Michael J. Decker; Enrique Vargas; Mercedes Villena; Rudy Soria
Elevated hemoglobin concentrations have been reported for high-altitude sojourners and Andean high-altitude natives since early in the 20th century. Thus, reports that have appeared since the 1970s describing relatively low hemoglobin concentration among Tibetan high-altitude natives were unexpected. These suggested a hypothesis of population differences in hematological response to high-altitude hypoxia. A case of quantitatively different responses to one environmental stress would offer an opportunity to study the broad evolutionary question of the origin of adaptations. However, many factors may confound population comparisons. The present study was designed to test the null hypothesis of no difference in mean hemoglobin concentration of Tibetan and Aymara native residents at 3,800–4,065 meters by using healthy samples that were screened for iron deficiency, abnormal hemoglobins, and thalassemias, recruited and assessed using the same techniques. The hypothesis was rejected, because Tibetan males had a significantly lower mean hemoglobin concentration of 15.6 gm/dl compared with 19.2 gm/dl for Aymara males, and Tibetan females had a mean hemoglobin concentration of 14.2 gm/dl compared with 17.8 gm/dl for Aymara females. The Tibetan hemoglobin distribution closely resembled that from a comparable, sea-level sample from the United States, whereas the Aymara distribution was shifted toward 3–4 gm/dl higher values. Genetic factors accounted for a very high proportion of the phenotypic variance in hemoglobin concentration in both samples (0.86 in the Tibetan sample and 0.87 in the Aymara sample). The presence of significant genetic variance means that there is the potential for natural selection and genetic adaptation of hemoglobin concentration in Tibetan and Aymara high-altitude populations. Am J Phys Anthropol 106:385–400, 1998. © 1998 Wiley-Liss, Inc.
Hemoglobin concentration of high-altitude Tibetans and Bolivian Aymara
(Wiley, 1998) Cynthia M. Beall; Gary M. Brittenham; Kingman P. Strohl; John Blangero; Sarah Williams‐Blangero; Melvyn C. Goldstein; Michael J. Decker; Enrique Vargas; Mercedes Villena; Rudy Soria
Elevated hemoglobin concentrations have been reported for high-altitude sojourners and Andean high-altitude natives since early in the 20th century. Thus, reports that have appeared since the 1970s describing relatively low hemoglobin concentration among Tibetan high-altitude natives were unexpected. These suggested a hypothesis of population differences in hematological response to high-altitude hypoxia. A case of quantitatively different responses to one environmental stress would offer an opportunity to study the broad evolutionary question of the origin of adaptations. However, many factors may confound population comparisons. The present study was designed to test the null hypothesis of no difference in mean hemoglobin concentration of Tibetan and Aymara native residents at 3,800-4,065 meters by using healthy samples that were screened for iron deficiency, abnormal hemoglobins, and thalassemias, recruited and assessed using the same techniques. The hypothesis was rejected, because Tibetan males had a significantly lower mean hemoglobin concentration of 15.6 gm/dl compared with 19.2 gm/dl for Aymara males, and Tibetan females had a mean hemoglobin concentration of 14.2 gm/dl compared with 17.8 gm/dl for Aymara females. The Tibetan hemoglobin distribution closely resembled that from a comparable, sea-level sample from the United States, whereas the Aymara distribution was shifted toward 3-4 gm/dl higher values. Genetic factors accounted for a very high proportion of the phenotypic variance in hemoglobin concentration in both samples (0.86 in the Tibetan sample and 0.87 in the Aymara sample). The presence of significant genetic variance means that there is the potential for natural selection and genetic adaptation of hemoglobin concentration in Tibetan and Aymara high-altitude populations.