Where the O2 goes to: preservation of human fetal oxygen delivery and consumption at high altitude.

Fetal growth is decreased at high altitude (> 2700 m). We hypothesized that variation in fetal O(2) delivery might account for both the altitude effect and the relative preservation of fetal growth in multigenerational natives to high altitude. Participants were 168 women of European or Andean ancestry living at 3600 m or 400 m. Ancestry was genetically confirmed. Umbilical vein blood flow was measured using ultrasound and Doppler. Cord blood samples permitted calculation of fetal O(2) delivery and consumption. Andean fetuses had greater blood flow and oxygen delivery than Europeans and weighed more at birth, regardless of altitude (+208 g, P < 0.0001). Fetal blood flow was decreased at 3600 m (P < 0.0001); the decrement was similar in both ancestry groups. Altitude-associated decrease in birth weight was greater in Europeans (-417 g) than Andeans (-228 g, P < 0.005). Birth weight at 3600 m was > 200 g lower for Europeans at any given level of blood flow or O(2) delivery. Fetal haemoglobin concentration was increased, decreased, and the fetal / curve was left-shifted at 3600 m. Fetuses receiving less O(2) extracted more (r(2) = 0.35, P < 0.0001). These adaptations resulted in similar fetal O(2) delivery and consumption across all four groups. Increased umbilical venous O(2) delivery correlated with increased fetal O(2) consumption per kg weight (r(2) = 0.50, P < 0.0001). Blood flow (r(2) = 0.16, P < 0.001) and O(2) delivery (r(2) = 0.17, P < 0.001) correlated with birth weight at 3600 m, but not at 400 m (r(2) = 0.04, and 0.03, respectively). We concluded that the most pronounced difference at high altitude is reduced fetal blood flow, but fetal haematological adaptation and fetal capacity to increase O(2) extraction indicates that deficit in fetal oxygen delivery is unlikely to be causally associated with the altitude- and ancestry-related differences in fetal growth.

Effect of high altitude on protein metabolism in Bolivian children.

In Bolivia, malnutrition in children is a major health problem that may be caused by inadequate protein, energy, and micronutrient intake; exposure to bacterial and parasitic infections; and life in a multistress environment (high altitude, cold, cosmic radiation, low ambient humidity). However, no data on protein absorption and utilization at high altitude were available. Therefore, we evaluated the effect of altitude on protein metabolism in Bolivian children. We measured protein utilization using leucine labeled with a stable isotope ((13)C) in two groups of healthy prepubertal children matched for age. Group 1 (n = 10) was examined at high altitude (HA) in La Paz (3600 m), and group 2 (n = 10) at low altitude (LA) in Santa Cruz (420 m). The nutritional status did not differ between groups but, as was to be expected, the HA group had higher hemoglobin concentration than the LA group. The children consumed casein that was intrinsically labeled with L-(1-(13)C) leucine and expired (13)CO(2) was analyzed. Samples of expired air were measured by isotope ratio mass spectrometer in Clermont-Ferrand. It was found that cumulative leucine oxidation ((13)CO(2)) at 300 min after ingestion was 19.7 +/- 4.9% at HA and 25.2 +/- 3.2% at LA. These results showed that protein absorption and/or utilization is significantly affected by altitude.

Augmented uterine artery blood flow and oxygen delivery protect Andeans from altitude-associated reductions in fetal growth.

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.

Greater uterine artery blood flow during pregnancy in multigenerational (Andean) than shorter-term (European) high-altitude residents.

Multigenerational (Andean) compared with shorter-term (European) high-altitude residents exhibit less hypoxia-associated reductions in birth weight. Because differences in arterial O(2) content are not responsible, we asked whether greater pregnancy-associated increases in uterine artery (UA) blood flow and O(2) delivery were involved. Serial studies were conducted in 42 Andean and 26 European residents of La Paz, Bolivia (3600 m) at weeks 20, 30, 36 of pregnancy and 4 mo postpartum using Doppler ultrasound. There were no differences postpartum but Andean vs. European women had greater UA diameter (0.65 +/- 0.01 vs. 0.56 +/- 0.01 cm), cross-sectional area (33.1 +/- 0.97 vs. 24.7 +/- 1.18 mm(2)), and blood flow at week 36 (743 +/- 87 vs. 474 +/- 36 ml/min) (all P < 0.05) and thus 1.6-fold greater uteroplacental O(2) delivery near term (126.82 +/- 18.47 vs. 80.33 +/- 8.69 ml O(2).ml blood(-1).min(-1), P < 0.05). Andeans had greater common iliac (CI) flow and lower external iliac relative to CI flow (0.52 +/- 0.11 vs. 0.95 +/- 0.14, P < 0.05) than Europeans at week 36. After adjusting for gestational age, maternal height, and parity, Andean babies weighed 209 g more than the Europeans. Greater UA cross-sectional area at week 30 related positively to birth weight in Andeans (r = +0.39) but negatively in Europeans (r = -0.37) (both P < 0.01). We concluded that a greater pregnancy-associated increase in UA diameter raised UA blood flow and uteroplacental O(2) delivery in the Andeans and contributed to their ability to maintain normal fetal growth under conditions of high-altitude hypoxia. These data implicate the involvement of genetic factors in protecting multigenerational populations from hypoxia-associated reductions in fetal growth, but future studies are required for confirmation and identification of the specific genes involved.

Determinants of blood oxygenation during pregnancy in Andean and European residents of high altitude.

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.

Maternal oxygen delivery is not related to altitude- and ancestry-associated differences in human fetal growth.

Fetal growth is reduced at high altitude, but the decrease is less among long-resident populations. We hypothesized that greater maternal uteroplacental O(2) delivery would explain increased fetal growth in Andean natives versus European migrants to high altitude. O(2) delivery was measured with ultrasound, Doppler and haematological techniques. Participants (n=180) were pregnant women of self-professed European or Andean ancestry living at 3600 m or 400 m in Bolivia. Ancestry was quantified using ancestry-informative single nucleotide polymorphism. The altitude-associated decrement in birth weight was 418 g in European versus 236 g in Andean women (P<0.005). Altitude was associated with decreased uterine artery diameter, volumetric blood flow and O(2) delivery regardless of ancestry. But the hypothesis was rejected as O(2) delivery was similar between ancestry groups at their respective altitudes of residence. Instead, Andean neonates were larger and heavier per unit of O(2) delivery, regardless of altitude (P<0.001). European admixture among Andeans was negatively correlated with birth weight at both altitudes (P<0.01), but admixture was not related to any of the O(2) transport variables. Genetically mediated differences in maternal O(2) delivery are thus unlikely to explain the Andean advantage in fetal growth. Of the other independent variables, only placental weight and gestational age explained significant variation in birth weight. Thus greater placental efficiency in O(2) and nutrient transport, and/or greater fetal efficiency in substrate utilization may contribute to ancestry- and altitude-related differences in fetal growth. Uterine artery O(2) delivery in these pregnancies was 99 +/- 3 ml min(-1), approximately 5-fold greater than near-term fetal O(2) consumption. Deficits in maternal O(2) transport in third trimester normal pregnancy are unlikely to be causally associated with variation in fetal growth.

Relevancia de los indicadores bioquímicos en la evaluación del estado nutricional / Relevance of biochemical indicators for evolution fo nutritional status

En este contexto, los indicadores bioquímicos(móleculas representativas de cambios nutricionales) van adquiriendo gran importancia dentrodel dignóstico nutricional debido a un mayor conocimiento del metabolismo de losdistintos nutrientes, sus interacciones y disponibilidad de técnicas de mediciónmás precisas. El estado nutricional(parte esencial del estado de salud), es la resultante del equilibrio entre aportes nutricionales y gastos energéticos, cuando disminuye el aporte nutricional proteíco-energético o de vitaminas y/o minerales por diversas causas o agresiones(hipoalimentación, infecciones, diarreas crónicas, trauma quirúrgico y otras) el estado nutricional se deteriora puesto que disminuye, la eficiencia de los procesos de defensa inmunitaria, fagocitosis,eritrocitosis, función respiratoria y otras, disminuyendo así la capacidad del organismo para responder a dichas agresiones, por lo tanto la morbimortalidad dependen en gran parte de la posibilidad de mantener un buen estado nutricional. Por esta razón es indispensable evaluar el estado nutricional del individuo para conocer su estado de salud, detectar su riesgo nutricional, conocer su respuesta a una terapia nutricional. A nivel comunitario, conocer la frecuencia y repartición de alteraciones nutricionales más extendidas, sus consecuencias para la salud, vida económica, productiva y distinguir posibilidades de intervención. Evaluaciónque implica un diagnóstico e interpretación de la situación nutricional a travésde la información recogida por exámenes clínicos, antropométricos, bioquímicos, funcionales e indirecto

Aspectos metodológicos del control de calidad intralaboratorio en química sanguínea / Methodologic aspects of quality control of a blood chemistry laboratory

El presente artículo trata sobre uno de los roles fundamentales del bioquímico clínico en el equipo de salud, es el de proporcionar datosconfiables y garantizados de los diferentes exámenes procesados en diversos líquidos biológicos con el fin de establecer un diagnóstico, pronóstico y prevencióndel estado de salud. En efecto, el bioquímico clínico al realizar una valoraciónde una determinada molécula pretende encontrar un equilibrio entre lo que sucedeen el interior del organismo y la sensibilidad de métodos químicos in vitrio, los cuales permiten detectar los cambios o transformaciones de ese mundo interior

Proteínas circulantes como indicadores del estado nutricional en niños de 10 a 12 años / Circulating proteins is indicators of nutritional status of children of 10-12 years old

Se estudiaron en los Andes y Llanos de Bolivia en forma transversal y abierta a noventa y tres niños mestizos con predominio aymara, entre 10 y 12 años de edad recientes a 3600 y 450 m.s.n.m. y de diferente nivel socioeconómico. Se dividio a estos prepúberes en cuatro grupos y se evaluó el estado nutricional a través de diversas variables bioquímicas marcadoras del estado nutricional y del estado inflamatorio, utilizando métodos colorimétricos é inmunoquímicos y criterios antropométricos como peso para edad, toda para edad, talla para edad, peso para talla, utizando puntos de corte 15 percentilo(para P/E)y 3 percentilo(paraP/E.T/E,P/T). Este último de acuerdo al NCHS. Se encuentran prevalencias elevadas de retraso del crecimiento en los niños de nivel socioeconómico bajo de baja y gran altura con puntos de corte 3 percentilo. En este mismo grupo de niños se encuentran tasas de prealbúmina disminuidas con relación a los niños de nivel socioeconómico alto de baja y gran altura. Este estudio muestra, la asociación entre el retardo de crecimiento en el grupo de niños de nivel socio-económico bajo de baja y gran altura, y la disminución de la tasa de prealbúmina. El factor socio-económico parece ser el factor más crítico para el estado nutricional de los niños prepúberes que la altura