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.     

急进高原大鼠肠黏膜机械屏障损伤后细胞自噬变化的初步研究

目的探讨急进高原大鼠肠黏膜机械屏障损伤后细胞自噬的变化情况。方法50只Wistar大鼠随机分为5组：平原组,急进高原6h组、12h组、24h组、48h组,每组各10只。通过低压低氧动物实验舱模拟急进海拔4767m建立急进高原大鼠模型。观察各组大鼠肠黏膜机械屏障损伤情况,用透射电镜观察肠上皮细胞中自噬体;用免疫组织化学法检测肠上皮细胞中自噬相关蛋白Beclinl及LC3B表达。结果与平原组比较,急进高原组可使其肠黏膜机械屏障发生损伤,并且在急进高原肠黏膜损伤6h后可观测到自噬体,24h后检测到自噬相关蛋白Beclinl及LC3B表达显著增高（P〈0．01）。结论急进高原组大鼠肠黏膜机械屏障损伤后自噬相关蛋白Beclinl及LC3B表达明显增加,表明急进高原大鼠肠黏膜机械屏障损伤后细胞自噬活性上调。     

Hemoglobin levels in a Himalayan high altitude population

This report presents data on hemoglobin concentrations in a sample of Himalayan high altitude natives measured at their habitual altitude of residence. In this sample of 270 healthy Tibetan adults resident at 3250–3560 m in Upper Chumik, Nepal, the mean hemoglobin concentration is 16.1 ± 1.2 gm/dl among adult males, 14.4 ± 1.4 gm/dl among premenopausal and 15.0 ± 1.1 gm/dl among postmenopausal adult females. 123 of 126 (98%) males, 96 of 100 (96%) premenopausal and 36 of 44 (82%) postmenopausal females have hemoglobin concentrations within two standard deviations of the sea level mean. These data demonstrate that a healthy population may reside at high altitude without the degree of elevation in hemoglobin widely known and cited for Andean highlanders. Comparing published data on mean hemoglobin concentrations of adult Himalayan and Andean samples residing between 3200 m and 4100 m reveals that Himalayan means are systematically lower. This in turn may account for the reported population differences in the prevalence of chronic mountain sickness (Monge's disease). It is hypothesized that Himalayan and Andean highlanders represent alternative patterns of high altitude hematological adaptation.     

谷氨酰胺对急进高原大鼠肠道微生态影响的实验研究

目的探讨谷氨酰胺对急进高原大鼠小肠黏膜形态结构及肠道微生态的影响。方法W istar大鼠50只,随机分为5组:对照组(A组)、3848米未干预组(B组)、3848米谷氨酰胺干预组(C组)、4767米未干预组(D组)和4767米谷氨酰胺干预组(E组),每组10只,急进海拔3848米和4767米造成大鼠急性缺氧模型,检测小肠黏膜上皮细胞形态结构、肠道菌群失衡及细菌易位的变化。结果高海拔缺氧组大鼠小肠黏膜变薄、肠黏膜水肿、绒毛短缩,肠道菌群失衡显著高于对照组(P0.05),且随着海拔升高,菌群失衡更明显。不同海拔高度细菌易位率也有差异。经谷氨酰胺干预后,肠道的菌群失衡及细菌易位率与高海拔缺氧组比较差异有显著性(P0.05)。结论急进高原缺氧环境可导致小肠黏膜损伤、肠道菌群失衡及细菌易位,肠黏膜屏障破坏,且随着海拔升高而上述改变更明显。谷氨酰胺具有保护肠黏膜屏障及调节肠道菌群失衡的作用。     

Effect of intermittent chronic exposure to hypoxia on feeding behaviour of rats

Healthy albino male rats were exposed to a simulated high altitude (HA) equivalent to 25000 ft (7620 m) for 6 h daily, continuously for 21 days to study the feeding behaviour. The 24-h food and water intake and body weight once in 3 days were recorded. Blood samples were drawn once a week from the retro-orbital venous plexus for blood sugar analysis. All the parameters were recorded before, during and after exposure to simulated HA. The results show a decrease in 24-h food and water intake and decreased gain in body weight during hypoxic exposure, which showed a tendency to come back to control during the post-exposure period. The blood sugar reflected a state of mild hyperglycaemia during exposure to HA.     

Effect of high altitude on sensitivity to the taste of phenylthiocarbamide

Sensitivity to the taste of phenylthiocarbamide (PTC) was studied using the Harris-Kalmus method in healthy human volunteers at sea level and then subsequently at an altitude of 3500 m over a period of 3 weeks, after which they were brought back to sea level. Blood sugar, insulin and blood cortisol levels were estimated weekly. The results indicated that, out of 51 subjects studied, 26 (55%) were PTC tasters at sea level. Eight of those unable to taste PTC at sea level tested as tasters at high altitude, and 2 of them reverted to being non-tasters on return to sea level. In the blood, an increase in cortisol and blood insulin levels was seen without any significant change in sugar levels. All the changes recorded at high altitude tended to return to basal values after re-induction to sea level. The study suggests that high-altitude hypoxia in some way, possibly involving changes in hormonal profile among other factors, causes an alteration in sensitivity to the taste of PTC, resulting in some of the individuals shifting to lower PTC sensitivity. Received: 24 November 1999 / Accepted: 25 January 2000     

Growth trends among male Bods of Ladakh--a high altitude population

A random sample of 274 native male Bods of Ladakh ranging in age from 11 to 19 years, living in Leh (Ladakh) at mean altitude of 3,514 metres, was studied. The pattern of growth of this sample was compared with the sea level Indians. The results indicate that: (1) The so called adolescent spurt is not well defined among Bod highlanders. (2) Bods grow faster than plain dwelling Indians and are taller and heavier at the age of 19 years. (3) The highlanders exhibit greater chest circumference than the lowland norms. This finding, similar to those among Andean natives, supports high altitude hypoxia's role in human growth and morphology.     

Growth of lowland native children of European Ancestry during sojourn at high altitude (3,200 m)

The moderate growth retardation frequently observed among children living at high altitude is usually assumed to result from hypoxic stress. However, such children are frequently from the poorer socioeconomic strata of their societies and may suffer malnutrition, poor hygiene, inadequate medical care, and overcrowding—factors also associated with growth retardation. The objective of this study was to determine if there is a statistically observable alteration in the growth of middle-class children of European ancestry during sojourn at high altitude. Semilongitudinal height/weight measurements were gathered retrospectively from medical records of 18 boys and 17 girls who were born at low altitude, were well-nourished and clinically normal, and who had lived at Achoma, Peru (altitude 3,200 m), continuously for 9–36 months. Measurements were divided, by sex, into four cohorts: I (3–6 months at Achoma), II (6–12 months), III (12–18 months), and IV (18–24 months); initial, presojourn, height and weight were also obtained. All heights and weights were normalized with age-specific reference values. Changes in Z scores (ΔZ) during sojourn were calculated for each subject by subtracting the score of the presojourn value from those of cohorts I–IV. Paired t-tests revealed, among the boys, a significant decline in Z score for weight during sojourn in all four cohorts. Weight scores for the girls also declined in all four cohorts, although only the change in cohort III was significant. Height scores showed a decline with time at sojourn in the boys, but in girls there is an initial drop followed by a steady increase to presojourn levels. These results are consistent with the view that moderate hypoxia exerts a primary growth-limiting effect even on healthy, well-nourished children.     

Effect of yogic exercises on thyroid function in subjects resident at sea level upon exposure to high altitude

Using radioactive iodine, the effect of 1 month's yogic exercises has been investigated on the thyroid function of subjects resident at sea level (SL) specially after their exposure to high altitude (HA). The results have been compared with a group of SL subjects who underwent physical training (PT) exercises for the same duration. Ten healthy male volunteers in the age range of 20–30 years were used as test subjects in this study with each serving as his own control. The subjects were randomly divided into two groups of 5 each. One group practised hatha yogic exercises, while the other group performed the regular PT exercises. The thyroidal accumulation and release of radioactive iodine have been measured in each of the subjects of both groups before and after 1 month of their respective exercises at SL. One month of yogic exercises at SL has been observed to cause a significant reduction in the trans-thy-roidal availability of radioiodine. The thyroid radioactivity in this group of subjects was always below normal levels with the exception of two peaks of radioactive iodine uptake, when the levels of radioactivity in the thyroid were similar to the control values of pre-yogic exercises. The release of radiolabel at 24–48 h was significantly increased after yogic exercises. In contrast, the subjects performing PT exercises for the same duration at SL showed significant thyroid uptake of radioactive iodine at 24 h. Subsequently their¹³¹I uptake continued to rise slowly until 72 h without any demonstrable thyroidal release of radiolabel. This indicated that increased thyroid activity was induced by conventional PT exercise. Exposure of SL residents to HA irrespective of their exercise regime altered the thyroidal handling of radioiodine. Thyroidal concentrations of freshly administered radioiodine at early and late sampling intervals were very high in both of the groups, especially the yogics, after their return to SL from HA. Possible mechanisms of the observed changes have been discussed.     

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) 43 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 (V?O² 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. © 1995 Wiley-Liss, Inc.     

添加益生元对急进高原大鼠肠黏膜屏障紧密连接蛋白Occludin的作用研究

目的探讨通过灌胃的方式给予益生元(低聚半乳糖)对急进高原大鼠肠黏膜屏障紧密连接Occludin蛋白的表达及作用。方法在3848米建立高原缺氧模型大鼠共48只,随机选24只为高原缺氧对照组,另24只为添加益生元组,再按2 d、4 d和6 d时间点,分为6组,每组8只。采用免疫组织化学法检测Occludin蛋白表达,用ELISA法测定回肠组织肿瘤坏死因子-α(TNF-α)、白介素-10(IL-10)。结果和高原缺氧组各时间点比较,添加益生元组Occludin蛋白表达显著升高(P<0.01),TNF-α水平降低、IL-10水平升高(P<0.05)。结论益生元可以增加急进高原缺氧大鼠肠黏膜紧密连接蛋白Occludin的表达,改善高原缺氧对大鼠肠黏膜屏障的破坏。     

Influence of vanadium on acclimatization of humans to high altitude

 The study was conducted on human volunteers as controls as well as after administration of vanadyl sulphate on induction to high altitude (HA) at 3500 m. The plasma vanadium contents were significantly reduced in the control group on abrupt induction to HA on days 3 and 10, indicating redistribution to other organs/tissues under the stressful situation. In the vanadium salt-treated group, plasma vanadium contents were similar to those obtained at sea-level. Administration of vanadyl sulphate did not act as a diuretic. Moreover the vanadium supplemented group drank more water and also excrete less urine than the control group. Received: 1 November 1995 / Accepted: 9 October 1996     

Myocardial hypertrophy in rats exposed to simulated high altitude

Myocardial hypertrophy in Sprague-Dawley adult rats exposed to hypobaric hypoxia (0.40 atmosphere of air/18 h daily for 7 days) in a hypobaric chamber was investigated. Changes in the myocardial mass were evaluated on the basis of the dry heart weight and expressed as mg/100 g of total body weight (mean +/- SEM). Data are presented indicating that: chronic hypobaric hypoxia causes a significant degree of myocardial hypertrophy in rats; hypertrophic process involves both ventricles (the right more than the left); removal of the hypoxic stimulus leads to the disappearance of hypertrophy when evaluated as an increase in dry heart weight; hypoxia affects the synthesis of a significant amount of connective tissue in the left ventricle, which is not exposed to pressure load. The r?le of neurohumoral factors (i.e., adrenergic stimulation and catecholamines) in the development of the ventricular hypertrophy is suggested.     

Secular change in growth of native children and adolescents at high altitude Huancayo,Peru (3,280 meters)

Stature and weight of native children, adolescents, and adults at Huancayo, Peru (3,280 meters), were measured in 1977, 1978, and 1982 and compared with mean statures and weights reported in previous studies. The data indicate that in Huancayo there has been a secular increment in child stature, sitting height, and weight from 1937 to 1978–1982. The observed changes in stature are related to a proportionally greater increment in leg length relative to trunk length. It is concluded that the observed secular increase in body size reflects changes in the standard of living and a greater influx of nonnative populations, which are usually characterized by greater stature than natives.     

Secular change in growth of native children and adolescents at high altitude I. Puno,Peru (3800 meters)

A cross sectional sample of 969 native males from Puno (Peru), altitude 3800 m, ranging in age from 7–20 years, and studied for body height, weight, sitting height, leg length, and chest circumference in 1980, were compared, from the point of view of secular trend, with another cross sectional sample of 992 native males from the same place, which were investigated in 1945. In addition, similar observations were carried out in 1980, in a group of 112 females. The data indicate that in Puno there has been no secular increment in the adult body size. However for all ages between 7 and 19 years, body weight and height were significantly greater in 1980 than in 1945. This may be due to earlier sexual maturation in the present generation.     

Body temperature regulation during acclimation to cold and hypoxia in rats

Extreme environmental conditions present challenges for thermoregulation in homoeothermic organisms such as mammals. Such challenges are exacerbated when two stressors are experienced simultaneously and each stimulus evokes opposing physiological responses. This is the case of cold, which induces an increase in thermogenesis, and hypoxia, which suppresses metabolism conserving oxygen and preventing hypoxaemia. As an initial approach to understanding the thermoregulatory responses to cold and hypoxia in a small mammal, we explored the effects of acclimation to these two stressors on the body temperature (T_b) and the daily and ultradian T_b variations of Sprague-Dawley rats. As T_b is influenced by sleep-wake cycles, these T_b variations reflect underlying adjustments in set-point and thermosensitivity. The T_b of rats decreased precipitously during initial hypoxic exposure which was more pronounced in cold (T_b=33.4±0.13) than in room temperature (T_b=35.74±0.17) conditions. This decline was followed by an increase in T_b stabilising at a new level ~0.5 °C and ~1.4 °C below normoxic values at room and cold temperatures, respectively. Daily T_b variations were blunted during hypoxia with a greater effect in the cold. Ultradian T_b variations exhibited daily rhythmicity that disappeared under hypoxia, independent of ambient temperature. The adjustments in T_b during hypoxia and/or cold are in agreement with the hypothesis that an initial decrease in the T_b set-point is followed by its partial re-establishment with chronic hypoxia. This rebound of the T_b set-point might reflect cellular adjustments that would allow animals to better deal with low oxygen conditions, diminishing the drive for a lower T_b set-point. Cold and hypoxia are characteristic of high altitude environments. Understanding how mammals cope with changes in oxygen and temperature will shed light into their ability to colonize new environments along altitudinal clines and increase our understanding of how T_b is regulated under stimuli that impose contrasting physiological constraints.     

Human nutrition in cold and high terrestrial altitudes

The calorie and nutritional requirements for a man working in an alien hostile environment of cold regions and high altitude are described and compared to those of normal requirements. Carbohydrates, fats and vitamins fulfilling the caloric and nutritional requirements are generally available in adequate amounts except under conditions of appetite loss. However, the proteins and amino acids should be provided in such a way as to meet the altered behavioral and metabolic requirements. Work in extreme cold requires fulfilling enhanced calorie needs. In high mountainous regions, cold combined with hypoxia produced loss of appetite and necessitated designing of special foods.     

The physical growth of high altitude Bolivian Aymara children

This study describes the growth characteristics of Aymara children living in Ancoraimes, Bolivia at altitudes between 3800 and 4000 meters. Anthropometric measurements were made on 510 children between the ages of 6. 0 and 20. 9 years, 360 males and 150 females. The growth pattern of Ancoraimes Aymara children is very similar to that of other high altitude Andean populations. They are greatly delayed in height and weight, exhibit little sexual dimorphism in body size and relative to stature, have larger chest dimensions than U.S. children. Compared to Quechua children living at higher altitudes in Peru, Ancoraimes children tend to be taller and heavier but have significantly smaller chest dimensions. Although the causes of the size differences between these two groups are not entirely clear, they may be due to the different altitudes at which the groups reside.