Plasticity of blood vessels of the heart and lungs in collateral circulation under conditions of high altitude]

The combination of the collateral blood flow in the heart and lungs with effects of Alpine hypoxia and pronounced additional loads was found to allow the detecting of plastical capacities of these organs in a sufficiently full volume. The experiments were performed in 273 dogs by microscopic, macro-microscopic, macroscopic and partly functional methods. The collateral coronary blood flow (after ligation of the anterior interventricular artery) under Alpine conditions (3200 m over the sea level) combined with compensatory hyperfunction of the heart (due to stenosing of the aorta arc), gets worse as compared with the conditions of the valley. In these experiments in mountains the extra- and intraorganic anastomoses are more pronounced, the capacity of the coronary artery branches being less pronounced than in the valley. The muscle fibres grow thicker, the heart weight enlarges, the diffusion distances of capillaries increase and the ratio of the arterial bed capacity and the heart weight decreases. Under Alphine conditions (as compared with the valley) the collateral blood flow of lungs deteriorates (after ligation of two lobar branches of the pulmonary artery or of the lobar vein) against the background of additional loads (stenosing of the aorta arc or pulmonectomy). Deterioration of the collateral bloodflow is related with the combination of conditions of the alphine hypoxia with additional loads resulting in a weakening or even block of compensatory reactions of pulmonary or bronchial arteries and veins.     

Abnormalities of blood coagulation at high altitude

Immediately on arrival of man at 3,600 m altitude there was a tendency towards hypercoagulation with increase in the platelet count, factor X, factor XII, thrombotest activity and thrombin clotting time with compensatory increase in fibrinolysis and reduction in factor VIII. During continuous stay there was a regression of the hypercoagulation state with reduction in platelet count, platelet factor 3, clot retraction, factor X, factor XII, thrombotest activity and persistence of increased fibrinolytic activity. The main difference in the hypercoagulation state in high-altitude pulmonary oedema and the corresponding highaltitude controls was the absence of a compensatory increase in fibrinolysis and increase in factor VIII. The main difference in the hypercoagulation state in highaltitude pulmonary hypertension and the corresponding high-altitude controls was an increase in platelet adhesiveness, platelet factor 3, factor V and factor VIII. The outstanding difference between high-altitude pulmonary oedema and highaltitude pulmonary hypertension was in the fibrinolytic activity and thrombin clotting time which were reduced in pulmonary oedema but were increased in pulmonary hypertension.

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Zusammenfassung Unmittelbar nach der Ankunft von Männern in 3.600 m Höhe zeigte sich eine Hyperkoagulation mit Anstieg der Plättchenzahl, Faktor X und Faktor XII, Thrombotest-Aktivität und Thrombin-Gerinnungszeit mit kompensatorischem Anstieg der Fibrinolyse und Verminderung von Faktor VIII. Bei längerem Aufenthalt ging der Hyperkoagulationszustand zurück mit verminderter Plättchenzahl, Plättchenfaktor 3, Thrombusretraktion, Faktor X, Faktor XII, Thrombotest-Aktivität und Verbleiben oder Anstieg der fibrinolytischen Aktivität. Der Hauptunterschied in der Hyperkoagulationsphase von Personen mit Lungenoedem und Gesunden in der Höhe war das Fehlen eines kompensatorischen Anstieges der Fibrinolyse und Faktor VIII. Der Hauptunterschied in der Hyperkoagulationsphase von Personen mit pulmonalem Hochdruck und Gesunden in der Höhe war ein Anstieg der Klebrigkeit der Plättchen, Plättchenfaktor 3, Faktor V und Faktor VIII. Die fibrinolytische Aktivität und die Thrombin-Gerinnungszeit waren bei Lungenoedem vermindert und bei pulmonalem Hochdruck erhöht.

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Resume A l'arrivée à 3.600 m d'altitude, on constate chez des sujets d'expérience une hypercoagulation accompagnée d'une hausse du nombre de plaquettes, du facteur X et du facteur XII, de l'activité du thrombotest et du temps de réaction de la thrombine. En compensation, on note une hausse de la fibrinolyse et une baisse du facteur VIII. Un séjour prolongé en altitude a pour conséquence une normalisation des réactions sanguines. Dans la phase d'hypercoagulation, la principale différence observée entre les personnes souffrant d'oedème pulmonaire et les personnes en bonne santé a été que, chez les premières, on n'a pas constaté de hausse compensatoire de la fibrinolyse ni de baisse du facteur VIII. Dans cette même phase, les personnes souffrant d'hypertension pulmonaires se distinguent des gens en bonne santé par le fait que les plaquettes collent entre elles et par une augmentation du facteur de plaques 3, du facteur V et du facteur VIII. L'activité fibrinolytique et le temps de coagulation de la thrombine sont diminués par l'oedème et augmentés par l'hypertension pulmonaire.

     

Fibrinopeptide A after strenuous physical exercise at high altitude

To examine hemostasis after physical exercise at altitudes easily accessible to tourists by public transport, 20 young male volunteers were exposed to 3,457 m above sea level. Ten of them were subjected to an exhaustive exercise for about 8 min on a bicycle ergometer. The preexercise samples (n = 20) taken 1 h after arrival showed no significant alteration of coagulation compared with control values at 600 m. After the exercise the clotting times (P less than 0.001) and euglobulin lysis times (P less than 0.001) were shortened, whereas factor VIII activity (P less than 0.001) was elevated. There was, however, no significant difference in fibrinopeptide A levels between the exercise and the control group. Ethanol gelation test remained negative. We found no rise in fibrin(ogen) degradation products and fibrin(ogen) fragment E and thus conclude that there is no evidence for clinically relevant intravascular coagulation after short-term strenuous physical exercise at altitude.     

Accuracy of handheld blood glucose meters at high altitude

Background

Due to increasing numbers of people with diabetes taking part in extreme sports (e.g., high-altitude trekking), reliable handheld blood glucose meters (BGMs) are necessary. Accurate blood glucose measurement under extreme conditions is paramount for safe recreation at altitude. Prior studies reported bias in blood glucose measurements using different BGMs at high altitude. We hypothesized that glucose-oxidase based BGMs are more influenced by the lower atmospheric oxygen pressure at altitude than glucose dehydrogenase based BGMs.

Methodology/Principal Findings

Glucose measurements at simulated altitude of nine BGMs (six glucose dehydrogenase and three glucose oxidase BGMs) were compared to glucose measurement on a similar BGM at sea level and to a laboratory glucose reference method. Venous blood samples of four different glucose levels were used. Moreover, two glucose oxidase and two glucose dehydrogenase based BGMs were evaluated at different altitudes on Mount Kilimanjaro. Accuracy criteria were set at a bias <15% from reference glucose (when >6.5 mmol/L) and <1 mmol/L from reference glucose (when <6.5 mmol/L). No significant difference was observed between measurements at simulated altitude and sea level for either glucose oxidase based BGMs or glucose dehydrogenase based BGMs as a group phenomenon. Two GDH based BGMs did not meet set performance criteria. Most BGMs are generally overestimating true glucose concentration at high altitude.

Conclusion

At simulated high altitude all tested BGMs, including glucose oxidase based BGMs, did not show influence of low atmospheric oxygen pressure. All BGMs, except for two GDH based BGMs, performed within predefined criteria. At true high altitude one GDH based BGM had best precision and accuracy.     

氧化应激在高原重体力劳动过程中急性高原反应发生中的作用

目的：观察氧化应激在高原重体力劳动过程中急性高原反应（AHAR）发生中的作用。方法：由低海拔（1500m）快速进入高原（3700m）并从事重体力劳动的男性官兵96名,年龄18～35岁。根据AHAR症状评分,分为重度AHAR组（A组,n=24）、轻中度AHAR组（B组,n=47）和无AHAR组（C组,n=25）,在该高度逗留50d后下撤前及返回低海拔（1500m）后12h、15d分别测定血清8．异前列腺素F2a（8-iso-PGF2a）、超氧化物歧化酶（SOD）、丙二醛（MDA）,并与低海拔（1500m）50名健康官兵（D组）比较。结果：A组血清8-iso-PGF2a、MDA[分别为（9．53±0．47）μg／L、（8．91±0．39）μmol／L]水平显著高于B组[分别为（8．34±O．42）μg／L、（7．31±0．32）μmol／L]、C组[分别为（7．02±0．48）μg／L、（6．41±0．23）μmol／L和D组[分别为（5．13±0．56）μg／L、（5．48±0．33）μmol／L]（均P〈0．01）,SOD（52．08±3．44）μ／mL水平显著低于B组（62．27±2．54）μ/mL、C组（71．99±3．35）μ/mL和D组（80．78±3．44）μ/mL,（均P〈0．01）,B组与c组之间和C组与D组之间亦有显著性差异（均P〈0．01）。海拔3700mAHAR总计分与血清8-iso-PGF2α、ⅣⅡ）A呈显著正相关（均P〈0．01）,与血清SOD显著负相关（P〈0．01）;8-iso-PGF2α、MDA与SOD显著负相关（均P〈0．01）。海拔3700m50d,血清8-iso-PGF2α、MDA水平显著高于,SOD水平显著低于海拔1500m12h、15d和D组（均P〈0．01）,海拔1500m12h与15d之间有显著性差异（均P〈0．01）,海拔1500m 15d与D组之间无显著性差异。结论：人体在高原低氧并重体力时氧化应激和氧化．抗氧化失衡与AHAR的发病和程度有密切关系,氧化应激和氧化．抗氧化失衡越严重,AHAR越重。返回低海拔后12h有显著改善,15d恢复到正常水平。     

高原鼠兔肺动脉血管功能及形态变化

目的研究肺循环对慢性缺氧的适应机理.方法在4300m的高度捕捉到高原适应动物鼠兔,带到2260m的高度并和10只Wistar大鼠在模拟4300m和5000m高度的低压仓内进行了肺动脉压的测定,观察肺组织学和组织免疫化学的改变.结果在2260m,鼠兔的Ppa明显低于Wistar大鼠,二者分别为(1.5±0@07)kPa和(2.9±1.1)kPa(P＜0.01).随着海拔高度的增加,鼠兔的Ppa上升不明显,而Wistar大鼠增加显著.左右心室比重鼠兔为0.22,而Wistar大鼠为0.45.鼠兔的Hb,Hct和2.3-DPG均低于大鼠.大鼠肺小血管周围可见肥大细胞(7.1±0.33)mm2,免疫组化染色mastcelltyptase颗粒呈阳性,鼠兔未发现肥大细胞及此种免疫反应.肺小动脉中层较鼠兔厚,分别为27.21%和9.22%,壁的厚度和Ppa有很好的(r=0.763).结论鼠兔无低氧性肺血管收缩,是一种遗传性适应.大鼠肥大细胞通过激活某些生长因子,在肺血管的再建过程中可能起一定作用.     

Aspects of physical activity in high altitude natives

Altitude adaptation was measured at sea level and high altitudes in sea level adapted and high altitude adapted natives. Tests of work capacity as measured by O₂ consumption, pulse rate, and ventilation rate are reported. It is noted that comparing our results with those of other investigators is difficult due to variations in terminology and procedure. This suggests the necessity of more precise definitions in studies of the physical activity of high altitude natives.     

The functional prognosis of physical working ability under conditions of extreme high altitude

The physical performance of climbers, those making high-altitude ascensions up to 8000 m, without additional oxygen was measured. Some functional criteria of the organism adaptation to exhausting physical loading at the high altitudes were selected. It was established that the forecasting of a successful ascension could be improved if the potential maximal oxygen uptake was added to the standard definition parameters of aerobic metabolism such as the maximal oxygen uptake and anaerobic threshold of oxygen uptake. The potential maximal oxygen uptake is considered to be the parameter of maximal oxygen uptake reserve growing in condition of realization of adaptive reaction to hypoxia.     

A stereological analysis of the ultrastructure of the lungs of wild mice living at low and high altitude

Stereological analysis of the ultrastructural composition of the pulmonary alveolo-capillary region of mice living at sea level compared with that of the same species (Phyllotis darwini) genetically adapted to life at 4,660 m reveals a trend at high altitude towards a greater volume percentage of tissue components. On a weight-specific basis, non-circulating tissue occupies a significantly greater volume in high-altitude mice, but air space and capillary contents are not correspondingly greater. Since the arithmetic mean thickness of the tissue layers and of the air-blood barrier are the same in the two altitudinal groups, the average alveolus must have a smaller volume in the high-altitude mice. Epithelial, endothelial, and erythrocyte surface areas per gram body weight are significantly greater in the high-altitude mice. Nuclear counts indicate that the larger lungs of mice adapted to high altitude are due to larger Pneumocyte I and II and endothelial cells rather than to an increase in the number of these cells. Hematocrits measured within the pulmonary capillaries in the two altitudinal groups were equal. An heretofore unrecognized feature of possible adaptive value is the surface/volume ratio of erythrocytes, which is similar for erythrocytes in alveolar space of mice at low and high altitudes but within lung capillaries is 14.7% greater at high altitude.