急性高原暴露后左心功能变化及与急性高原病的关系

目的：研究青年男性由平原急进高原后心脏血流动力学变化及其与急性高原病的关系。方法：分别检测218名健康青年男性在平原及急进高原24h内的血压、心卒和血氧饱和度,使用彩色多普勒超声仪检测左心功能;根据路易斯湖评分标准将受试者分为急性高原病纽（AMS组）和无急性高原病组（无AMS组）。结果：急性高原暴露后心率、舒张压、平均动脉压、左室射血分数、每搏输出量、每博指数、心输出量、心脏指数显著增加（P〈0．05）,血氧饱和度、左室收缩末容积则显著降低（P〈0．05）;急进高原后AMS组心率、收缩压、平均动脉压显著高于无AMS组（P〈0．05）,每博指数、左室舒张末容积显著低于无AMS组（P〈0．05）。结论：健康男性青年急性高原暴露后左心室收缩功能增强,左室舒张末容积、心率、每博指数可能作为预测急性高原病的参考指标。     

Effect of repeated normobaric hypoxia exposures during sleep on acute mountain sickness, exercise performance, and sleep during exposure to terrestrial altitude

There is an expectation that repeated daily exposures to normobaric hypoxia (NH) will induce ventilatory acclimatization and lessen acute mountain sickness (AMS) and the exercise performance decrement during subsequent hypobaric hypoxia (HH) exposure. However, this notion has not been tested objectively. Healthy, unacclimatized sea-level (SL) residents slept for 7.5 h each night for 7 consecutive nights in hypoxia rooms under NH [n = 14, 24 ± 5 (SD) yr] or "sham" (n = 9, 25 ± 6 yr) conditions. The ambient percent O(2) for the NH group was progressively reduced by 0.3% [150 m equivalent (equiv)] each night from 16.2% (2,200 m equiv) on night 1 to 14.4% (3,100 m equiv) on night 7, while that for the ventilatory- and exercise-matched sham group remained at 20.9%. Beginning at 25 h after sham or NH treatment, all subjects ascended and lived for 5 days at HH (4,300 m). End-tidal Pco(2), O(2) saturation (Sa(O(2))), AMS, and heart rate were measured repeatedly during daytime rest, sleep, or exercise (11.3-km treadmill time trial). From pre- to posttreatment at SL, resting end-tidal Pco(2) decreased (P < 0.01) for the NH (from 39 ± 3 to 35 ± 3 mmHg), but not for the sham (from 39 ± 2 to 38 ± 3 mmHg), group. Throughout HH, only sleep Sa(O(2)) was higher (80 ± 1 vs. 76 ± 1%, P < 0.05) and only AMS upon awakening was lower (0.34 ± 0.12 vs. 0.83 ± 0.14, P < 0.02) in the NH than the sham group; no other between-group rest, sleep, or exercise differences were observed at HH. These results indicate that the ventilatory acclimatization induced by NH sleep was primarily expressed during HH sleep. Under HH conditions, the higher sleep Sa(O(2)) may have contributed to a lessening of AMS upon awakening but had no impact on AMS or exercise performance for the remainder of each day.     

Plasma cytokine profiling to predict susceptibility to acute mountain sickness

Extensive studies have been performed on acute mountain sickness (AMS), but biomarkers predicting AMS are lacking. Presently, the mainstay methods to identify AMS biomarkers include proteomic and genetic methods at high altitudes or in hypoxic simulated chambers. In the present study, we compared plasma cytokine profiles between AMS-susceptible individuals and AMS-resistant individuals at low altitude by cytokine array analysis. In total, 75 differentially expressed cytokines were identified between AMS-susceptible individuals and AMS-resistant individuals, most involved in inflammation. A quantifiable human custom cytokine antibody array was then used to further test results of cytokine array analysis. Compared to AMS-resistant individuals, the level of insulin-like growth factor binding protein 6 (IGFBP-6) was significantly lower in AMS-susceptible individuals (37,318.99 ± 23,493.11 pg/mL and 25,665.38 ± 25,691.29 pg/mL, respectively; P = 0.04). Conversely, the levels of serum amyloid A1 (SAA1), dickkopf WNT signaling pathway inhibitor 4 (Dkk4), and interleukin 17 receptor A (IL-17RA) were significantly higher in AMS-susceptible individuals than in AMS-resistant individuals (SAA1: 4,069.69 ± 2,502.93 pg/mL vs. 2,994.98 ± 2,295.91 pg/mL, P = 0.05; Dkk4: 2,090.00 ± 2,094.89 pg/mL vs. 1,049.88 ± 1,690.93 pg/mL, P = 0.07; IL-17RA: 11.52 ± 8.33 pg/mL vs. 8.67 ± 6.22 pg/mL, P = 0.08). Although further in-depth research is required to examine the possible role of these cytokines in the development of AMS, these four cytokines may be of use in predicting AMS-susceptibility in a low-altitude environment.     

Effects of acute exposure to high altitude on ventilatory drive and respiratory pattern

To assess changes in ventilatory regulation in terms of central drive and timing, on exposure to high altitude, and the effects of induced hyperoxia at high altitude, six healthy normal lowland subjects (mean age 19.5 +/- 1.64 yr) were studied at low altitude (518 m) and on the first 4 days at high altitude (3,940 m). The progressive increase in resting expired minute ventilation (VE; control mean 9.94 +/- 1.78 to 14.25 +/- 2.67 l/min on day 3, P less than 0.005) on exposure to high altitude was primarily due to a significant increase in respiratory frequency (f; control mean 15.6 +/- 3.5 breaths/min to 23.8 +/- 6.2 breaths/min on day 3, P less than 0.01) with no significant change in tidal volume (VT). The increase in f was due to significant decreases in both inspiratory (TI) and expiratory (TE) time per breath; the ratio of TI to TE increased significantly (control mean 0.40 +/- 0.08 to 0.57 +/- 0.14, P less than 0.025). Mouth occlusion pressure did not change significantly, nor did the ratio of VE to mouth occlusion pressure. The acute induction of hyperoxia for 10 min at high altitude did not significantly alter VE or the ventilatory pattern. These results indicate that acute exposure to high altitude in normal lowlanders causes an increase in VE primarily by an alteration in central breath timing, with no change in respiratory drive. The acute relief of high altitude hypoxia for 10 min has no effect on the increased VE or ventilatory pattern.     

高原肺水肿易感基因多态性的全基因组关联分析

目的：高原肺水肿严重影响高原人群的健康。筛选高原肺水肿易感基因以用于高原肺水肿易感者的评估及防护。方法：利用Affymetrix SNP Array6．0芯片对23例高原肺水肿患者和17个健康对照进行全基因组SNP分型,利用PLINK软件进行了全基因组关联分析,利用Go和Pathway软件进行分析及作图。结果：全基因组关联分析获得39个相对显著的SNPs位点（P〈10^-4）。通过对这些SNP位点附近27个基因的c0和Pathway富集分析,发现这些基因主要参与细胞增殖调控过程、氮代谢过程和G蛋白耦联受体蛋白信号转导通路等。结论：本文发现的多态性位点及相关基因可能与高原肺水肿易感性相关。     

急性高原病患者血清和支气管肺泡灌洗液炎性反应物的改变

目的：探讨炎症反应在急性高原病发病中的作用。方法：采用支气管-肺泡灌洗法及单向免疫扩散测量法。结果：HAPE患者外周血中C-反性蛋白及免疫球蛋白(IgG、IgA、IgM)含量均显著高于HAAR组及对照组,补体C3、C4与对照组差别无显著性;HAPE患者肺泡灌洗液中含有大量蛋白质、红细胞及白细胞,含有C-反应蛋白,大量的免疫球蛋白(IgG、IgA、IgM)和补体C3-C4。结论：在HAPE发病过程中,除了肺动脉高压是其发病的重要因素外,炎症损伤亦起一定作用;而HAAR发病过程中,未见炎性反应发生。     

Current prevention and management of acute mountain sickness.

Acute mountain sickness was known to the Chinese in ancient times, as they traversed mountain passes between the Great Headache and Little Headache mountains into present-day Afghanistan. The Jesuit priest, Father Joseph Acosta, lived in Peru during the sixteenth century; he described both this syndrome and deaths which occurred in the high Andes. The incidence of high-altitude illness will rise as previously remote sites become more accessible to trekkers and skiers. Prevention and treatment are important concerns for those physicians who wish to advise their more adventuresome patients properly. This article incorporates a selected review of pertinent investigations, in the English-language literature over the past five years, into material previously presented at travel symposia for clinicians managing the prophylaxis and treatment of acute mountain sickness.     

Influence of acute exposure to high altitude on Basal and postprandial plasma levels of gastroenteropancreatic peptides

Acute mountain sickness (AMS) is characterized by headache often accompanied by gastrointestinal complaints that vary from anorexia through nausea to vomiting. The aim of this study was to investigate the influence of high altitude on plasma levels of gastroenteropancreatic (GEP) peptides and their association to AMS symptoms. Plasma levels of 6 GEP peptides were measured by radioimmunoassay in 11 subjects at 490 m (Munich, Germany) and, after rapid passive ascent to 3454 m (Jungfraujoch, Switzerland), over the course of three days. In a second study (n = 5), the same peptides and ghrelin were measured in subjects who consumed standardized liquid meals at these two elevations. AMS symptoms and oxygen saturation were monitored. In the first study, both fasting (morning 8 a.m.) and stimulated (evening 8 p.m.) plasma levels of pancreatic polypeptide (PP) and cholecystokinin (CCK) were significantly lower at high altitude as compared to baseline, whereas gastrin and motilin concentrations were significantly increased. Fasting plasma neurotensin was significantly enhanced whereas stimulated levels were reduced. Both fasting and stimulated plasma motilin levels correlated with gastrointestinal symptom severity (r = 0.294, p = 0.05, and r = 0.41, p = 0.006, respectively). Mean O₂-saturation dropped from 96% to 88% at high altitude. In the second study, meal-stimulated integrated ( = area under curve) plasma CCK, PP, and neurotensin values were significantly suppressed at high altitude, whereas integrated levels of gastrin were increased and integrated VIP and ghrelin levels were unchanged. In summary, our data show that acute exposure to a hypobaric hypoxic environment causes significant changes in fasting and stimulated plasma levels of GEP peptides over consecutive days and after a standardized meal. The changes of peptide levels were not uniform. Based on the inhibition of PP and neurotensin release a reduction of the cholinergic tone can be postulated.