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acclimatization to high altitude

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https://www.readbyqxmd.com/read/29304526/thromboelastometry-and-platelet-function-during-acclimatization-to-high-altitude
#1
Alistair S Rocke, Gordon G Paterson, Matthew T Barber, Alexander I R Jackson, Shona Main, Calum Stannett, Martin F Schnopp, J Kenneth Baillie, Elizabeth H Horne, Carl Moores, Paul Harrison, Alastair F Nimmo, A A Roger Thompson
Interaction between hypoxia and coagulation is important given the increased risk of thrombotic diseases in chronically hypoxic patients who reside at sea level and in residents at high altitude. Hypoxia alters the proteome of platelets favouring a prothrombotic phenotype, but studies of activation and consumption of specific coagulation factors in hypoxic humans have yielded conflicting results. We tested blood from 63 healthy lowland volunteers acclimatizing to high altitude (5,200 m) using thromboelastometry and assays of platelet function to examine the effects of hypoxia on haemostasis...
January 2018: Thrombosis and Haemostasis
https://www.readbyqxmd.com/read/29288803/cardioprotection-after-acute-exposure-to-simulated-high-altitude-in-rats-role-of-nitric-oxide
#2
Pablo H La Padula, Melisa Etchegoyen, Analia Czerniczyniec, Barbara Piotrkowski, Silvia Lores Arnaiz, Jose Milei, Lidia E Costa
AIM: In previous studies, upregulation of NOS during acclimatization of rats to sustained hypobaric hypoxia was associated to cardioprotection, evaluated as an increased tolerance of myocardium to hypoxia/reoxygenation. The objective of the present work was to investigate the effect of acute hypobaric hypoxia and the role of endogenous NO concerning cardiac tolerance to hypoxia/reoxygenation under β-adrenergic stimulation. METHODS: Rats were submitted to 58.7 kPa in a hypopressure chamber for 48 h whereas their normoxic controls remained at 101...
December 27, 2017: Nitric Oxide: Biology and Chemistry
https://www.readbyqxmd.com/read/29231767/high-altitude-induced-alterations-in-gut-immune-axis-a-review
#3
Kunjan Khanna, K P Mishra, Lilly Ganju, Bhuvnesh Kumar, Shashi Bala Singh
High-altitude sojourn above 8000 ft is increasing day by day either for pilgrimage, mountaineering, holidaying or for strategic reasons. In India, soldiers are deployed to these high mountains for their duty or pilgrims visit to the holy places, which are located at very high altitude. A large population also resides permanently in high altitude regions. Every year thousands of pilgrims visit Holy cave of Shri Amarnath ji, which is above 15 000 ft. The poor acclimatization to high altitude may cause alteration in immunity...
December 12, 2017: International Reviews of Immunology
https://www.readbyqxmd.com/read/29177389/-between-the-acclimatization-to-high-altitude-the-medical-anthropology-and-the-civilizing-utopia-mapping-of-the-evolution-of-thought-of-carlos-monge-medrano-on-the-health-illness-process-of-andean-populations
#4
Juan P Murillo
The main objective of this study is to describe how the ideas of Carlos Monge respect to high altitude sickness developed and how these were being deployed in the framework of the discussions on the living conditions of indigenous populations in the period 1928-1963. I postulate that the form how the Monge's paradigm was proposed, the tensions produced by various alternative movements and the way these contradictions were resolved were central, both for the subsequent development of different scientific disciplines and for their different institutional expressions in Peru...
April 2017: Revista Peruana de Medicina Experimental y Salud Pública
https://www.readbyqxmd.com/read/29158642/insights-into-nuclear-dna-content-hydrogen-peroxide-and-antioxidative-enzyme-activities-during-transverse-thin-cell-layer-organogenesis-and-ex-vitro-acclimatization-of-malaxis-wallichii-a-threatened-medicinal-orchid
#5
Biswajit Bose, Suman Kumaria, Hiranjit Choudhury, Pramod Tandon
Malaxis wallichii (Lindl.) Deb, a small, perennial, monopodial, terrestrial orchid, is endemic to tropical Himalayas at an altitude of 1200-2000 m asl. The pseudobulbs are important ingredients of century old drug 'Ashtavarga' and a polyherbal energetic tonic 'Chyavanprash'. An efficient genetically stable in vitro propagation protocol using transverse thin cell layer culture system was established for M. wallichii. In the present report, meta-topolin alone proved to be three times more beneficial compared to other routinely used cytokinins in inducing highest number of shoot buds, plant height and growth of regenerated shoots...
October 2017: Physiology and Molecular Biology of Plants: An International Journal of Functional Plant Biology
https://www.readbyqxmd.com/read/29157337/simulated-high-altitude-helium-oxygen-diving
#6
Lu Shi, Yan-Meng Zhang, Katsuura Tetsuo, Zhong-Yuan Shi, Yi-Qun Fang, Petar J Denoble, Yang-Yang Li
BACKGROUND: Experience with commercial heliox diving at high altitude is limited. The purpose of this study was to evaluate the effects of acute high-altitude exposure on fitness to dive and the safety of decompression after heliox diving while using U.S. Navy heliox decompression tables with Cross correction. METHOD: Four professional male divers were consecutively decompressed in a hypo- and hyperbaric chamber to altitudes of 3000 m (9842.5 ft), 4000 m (13,123...
December 1, 2017: Aerospace Medicine and Human Performance
https://www.readbyqxmd.com/read/29149296/comparative-transcriptomics-of-five-high-altitude-vertebrates-and-their-low-altitude-relatives
#7
Qianzi Tang, Yiren Gu, Xuming Zhou, Long Jin, Jiuqiang Guan, Rui Liu, Jing Li, Kereng Long, Shilin Tian, Tiandong Che, Silu Hu, Yan Liang, Xuemei Yang, Xuan Tao, Zhijun Zhong, Guosong Wang, Xiaohui Chen, Diyan Li, Jideng Ma, Xun Wang, Miaomiao Mai, An'an Jiang, Xiaolin Luo, Xuebin Lv, Vadim N Gladyshev, Xuewei Li, Mingzhou Li
Background: Species living at high altitude are subject to strong selective pressures due to inhospitable environments (e.g., hypoxia, low temperature, high solar radiation, and lack of biological production), making these species valuable models for comparative analyses of local adaptation. Studies that examined high-altitude adaptation identified a vast array of rapidly evolving genes that characterize the dramatic phenotypic changes in high-altitude animals. However, how high-altitude environment shapes gene expression programs remains largely unknown...
November 15, 2017: GigaScience
https://www.readbyqxmd.com/read/29130497/ubc-nepal-expedition-acclimatization-to-high-altitude-increases-spinal-motoneurone-excitability-during-fatigue-in-humans
#8
Luca Ruggiero, Alexandra F Yacyshyn, Jane Nettleton, Chris J McNeil
The fatigue-induced failure of the motor cortex to drive muscles maximally increases in acute hypoxia (AH) compared to normoxia (N) but improves with acclimatization (chronic hypoxia; CH). Despite their importance to muscle output, it is unknown how locomotor motoneurones in humans are affected by hypoxia and acclimatization. Eleven participants performed 16 min of submaximal (25% maximal torque, MVC) intermittent isometric elbow flexions in N, AH (environmental chamber), and CH (7-14 days at 5050 m) (PI O2 =  140, 74, and 76 mmHg, respectively)...
November 11, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/29130390/investigation-of-the-differences-between-the-tibetan-and-han-populations-in-the-hemoglobin-oxygen-affinity-of-red-blood-cells-and-in-the-adaptation-to-high-altitude-environments
#9
Cuiying Li, Xiaowei Li, Juan Liu, Xiu Fan, Guoxing You, Lian Zhao, Hong Zhou, Jingqi Li, Huifen Lei
OBJECTIVE: High altitude is characterized by low oxygen pressure, resulting in multiple adaptive responses. Tibetans who have lived in the plateau for thousands of years have developed unique phenotypes, such as downregulation of the HIF pathway through EPAS1 and EGLN1 gene mutation. However, the changes of hemoglobin-oxygen affinity under hypoxia environment remain elusive. METHODS: A blood cell analyzer and a blood oxygen analyzer were used to conduct routine blood tests and measure the oxygen affinity P50 in in the Han population that rapidly entered the plateau (for 3-7 days), the plateau-acclimatized Han population (residing for 30 days on the plateau), the plateau Han population (more than 10 years on the plateau), and the Tibetan population...
November 12, 2017: Hematology (Amsterdam, Netherlands)
https://www.readbyqxmd.com/read/29078168/stat3-rxr-nrf2-activates-systemic-redox-and-energy-homeostasis-upon-steep-decline-in-po2-gradient
#10
Subhojit Paul, Anamika Gangwar, Kalpana Bhargava, Yasmin Ahmad
Hypobaric hypoxia elicits several patho-physiological manifestations, some of which are known to be lethal. Among various molecular mechanisms proposed so far, perturbation in redox state due to imbalance between radical generation and antioxidant defence is promising. These molecular events are also related to hypoxic status of cancer cells and therefore its understanding has extended clinical advantage beyond high altitude hypoxia. In present study, however, the focus was to understand and propose a model for rapid acclimatization of high altitude visitors to enhance their performance based on molecular changes...
October 17, 2017: Redox Biology
https://www.readbyqxmd.com/read/28948697/sustained-sympathetic-activity-in-altitude-acclimatizing-lowlanders-and-high-altitude-natives
#11
C Lundby, J Calbet, G van Hall, B Saltin, M Sander
Combined results from different independent studies suggest that acclimatization to high altitude induces a slowly developing sympathetic activation, even at levels of hypoxia that cause no acute chemoreflex-mediated sympathoexcitation. We here provide direct neurophysiological evidence for this phenomenon. In eight Danish lowlanders, we quantified mean arterial blood pressure (MAP), heart rate (HR), and muscle sympathetic nerve activity (MSNA), twice at sea level (normoxia and with acute hypoxic exposure to 12...
September 25, 2017: Scandinavian Journal of Medicine & Science in Sports
https://www.readbyqxmd.com/read/28939210/toward-a-blood-borne-biomarker-of-chronic-hypoxemia-red-cell-distribution-width-and-respiratory-disease
#12
Joseph W Yčas
Hypoxemia (systemic oxygen desaturation) marks the presence, risk, and progression of many diseases. Episodic or nocturnal hypoxemia can be challenging to detect and quantify. A sensitive, specific, and convenient marker of recent oxygen desaturation represents an unmet medical need. Observations of acclimatization to high altitude in humans and animals reveals several proteosomic, ventilatory, and hematological responses to low oxygen tension. Of these, increased red cell distribution width (RDW) appears to have the longest persistence...
2017: Advances in Clinical Chemistry
https://www.readbyqxmd.com/read/28931132/oxygen-saturation-increases-over-the-course-of-the-night-in-mountaineers-at-high-altitude-3050-6354-m
#13
Markus Tannheimer, Rianne van der Spek, Florian Brenner, Raimund Lechner, Jürgen M Steinacker, Gunnar Treff
Background: Blood oxygen saturation (SpO 2 ) is frequently measured to determine acclimatization status in high-altitude travellers. However, little is known about nocturnal time course of SpO 2 (SpO 2N ), but alterations in SpO 2N might be practically relevant as well. To this end, we describe the time-course of SpO 2N in mountaineers at high altitude. Methods: SpO 2N was continuously measured in ten male mountaineers during a three-week expedition in Peru (3,050-6,354m)...
September 1, 2017: Journal of Travel Medicine
https://www.readbyqxmd.com/read/28910914/-changes-to-sleep-patterns-in-young-migrants-at-high-altitude
#14
Z D Ha, K L Pan, X L Jian, J P Luo, S Q Guan, W W Guo
Objective: To explore the relationship between the level of acclimatization and the changes to sleep architecture in migrants at high altitude. Methods: Nocturnal sleep recordings of 50 subjects aged between 18 and 25 years [mean age (20.9±2.0) years] were analyzed. Those young volunteers were divided into 3 700 m-3 m group(n=10, migrated to an altitude of 3 700 metres for 3 months), 3 700 m-1 y group(n=10, for 1 year) , 5 380 m-3 m group(n=8), 5 380 m-1 y group(n=9), and compared with a control group(n=13, at 1 400 m altitude)...
September 12, 2017: Chinese Journal of Tuberculosis and Respiratory Diseases
https://www.readbyqxmd.com/read/28860174/ubc-nepal-expedition-acute-alterations-in-sympathetic-nervous-activity-do-not-influence-brachial-artery-endothelial-function-at-sea-level-and-high-altitude
#15
Michael M Tymko, Joshua C Tremblay, Craig D Steinback, Jonathan P Moore, Alex B Hansen, Alexander Patrician, Connor A Howe, Ryan L Hoiland, Daniel J Green, Philip N Ainslie
Evidence indicates that increases in sympathetic nervous activity (SNA), and acclimatization to high-altitude (HA), may reduce endothelial function as assessed by brachial artery flow-mediated dilatation (FMD); however, it is unclear whether such changes in FMD are due to direct vascular constraint, or consequential altered hemodynamics (e.g. shear stress) associated with increased SNA as a consequence of exposure to HA. We hypothesized that: 1) at rest, SNA would be elevated and FMD would be reduced at HA compared to sea-level (SL); and 2) at SL and HA, FMD would be reduced when SNA was acutely increased, and elevated when SNA was acutely decreased...
August 31, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28860167/measuring-high-altitude-adaptation
#16
Lorna G Moore
High altitudes (>8000 ft or 2500 m) provide an experiment of nature for measuring adaptation and the physiological processes involved. Studies conducted over the past ~25 years in Andeans, Tibetans, and less often Ethiopians show varied but distinct O2 transport traits from those of acclimatized newcomers, providing indirect evidence for genetic adaptation to high altitude. Short-term (acclimatization, developmental) and long-term (genetic) responses to high altitude exhibit a temporal gradient such that, while all influence O2 content, the latter also improve O2 delivery and metabolism...
August 31, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28855086/hematocrit-of-mammals-artiodactyla-carnivora-primates-at-1500m-and-2100m-altitudes
#17
Jacopo P Mortola, DeeAnn Wilfong
The rise in hematocrit (Hct) is one of the hallmarks of human acclimatization to high altitude and, in chronic conditions, reflects the hypoxia-induced polycythemia. However, it is not a uniform response among domestic species and it is not found in Andean camelids, species long adapted to high altitudes. Hence, we asked to what extent the polycythemia of humans is common among mammals. Hct data were collected from captive mammals of three orders (Primates, Artiodactyla, Carnivora), 70 specimens of 33 species at ∼1500m altitude (barometric pressure Pb=635mmHg) and 296 specimens of 64 species at ∼2100m (Pb=596mmHg), long-term residents at those altitudes...
July 8, 2017: Zoology: Analysis of Complex Systems, ZACS
https://www.readbyqxmd.com/read/28818999/short-term-arrival-strategies-for-endurance-exercise-performance-at-moderate-altitude
#18
Joshua L Foss, Keren Constantini, Timothy D Mickleborough, Robert F Chapman
For sea level-based endurance athletes who compete at moderate and high altitudes, many are not logistically able to arrive at altitude weeks prior to the event to fully acclimatize. For those who can only arrive at altitude the night before competition, we asked if there is a physiological and performance advantage in reducing altitude exposure time to two hours prior to competition. On three separate visits, ten cyclists completed overnight laboratory exposures of: 1) a 14-hour exposure to normobaric hypoxia (16...
August 17, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28798201/remote-ischemic-preconditioning-does-not-prevent-acute-mountain-sickness-after-rapid-ascent-to-3450-m
#19
Marc M Berger, Franziska Macholz, Lukas Lehmann, Daniel Dankl, Marcel Hochreiter, Bernhard Bacher, Peter Bärtsch, Heimo Mairbäurl
Remote ischemic preconditioning (RIPC) has been shown to protect remote organs, such as the brain and the lung, from damage induced by subsequent hypoxia or ischemia. Acute mountain sickness (AMS) is a syndrome of non-specific neurologic symptoms and in high altitude pulmonary edema excessive hypoxic pulmonary vasoconstriction (HPV) plays a pivotal role. We hypothesized that RIPC protects the brain from AMS and attenuates the magnitude of HPV after rapid ascent to 3450 m. Forty non-acclimatized volunteers were randomized into 2 groups...
August 10, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28705998/is-normobaric-hypoxia-an-effective-treatment-for-sustaining-previously-acquired-altitude-acclimatization
#20
Beth A Beidleman, Charles S Fulco, Bruce S Cadarette, Allen Cymerman, Mark J Buller, Roy M Salgado, Alexander M Posch, Janet E Staab, Ingrid V Sils, Beau R Yurkevicius, Adam J Luippold, Alexander P Welles, Stephen R Muza
This study examined whether normobaric hypoxia (NH) treatment is more efficacious for sustaining high altitude (HA) acclimatization during re-introduction to altitude (RA) than no treatment at all. Seventeen sea level (SL) residents (age=23±6yrs; mean±SE) completed in the following order: 1)4d of SL testing, 2)12d of high altitude (HA) acclimatization at 4300m, 3)12d at SL post HA acclimatization (Post) where each received either NH (n=9;FiO2=0.122) or Sham (n=8;FiO2=0.207) treatment, and 4)24-h re-introduction to 4300m altitude (RA) in a hypobaric chamber...
July 13, 2017: Journal of Applied Physiology
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