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acclimatization to high altitude

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https://www.readbyqxmd.com/read/29149296/comparative-transcriptomics-of-five-high-altitude-vertebrates-and-their-low-altitude-relatives
#1
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
#2
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
#3
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
#4
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
#5
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
#6
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
#7
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
#8
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
#9
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
#10
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
#11
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
#12
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
#13
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
#14
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
https://www.readbyqxmd.com/read/28705997/evidence-from-high-altitude-acclimatization-for-an-integrated-cerebrovascular-and-ventilatory-hypercapnic-response-but-different-responses-to-hypoxia
#15
Zachary M Smith, Erin Krizay, Rui Carlos Sa, Ethan T Li, Miriam Scadeng, Frank L Powell, David J Dubowitz
Ventilation and cerebral blood flow (CBF) are both sensitive to hypoxia and hypercapnia. To compare chemosensitivity in these two systems, we made simultaneous measurements of ventilatory and cerebrovascular responses to hypoxia and hypercapnia in 35 normal human subjects before and after acclimatization to hypoxia. Ventilation and CBF were measured during stepwise changes in isocapnic hypoxia and iso-oxic hypercapnia. We used MRI to quantify actual cerebral perfusion. Measurements were repeated after 2-days of acclimatization to hypoxia at 3,800m altitude (PiO2 = 90 Torr) to compare plasticity in the chemosensitivity of these two systems...
July 13, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28684588/dietary-nitrate-supplementation-increases-acute-mountain-sickness-severity-and-sense-of-effort-during-hypoxic-exercise
#16
Gabriella M K Rossetti, Jamie H Macdonald, Lee J Wylie, Samuel J Little, Victoria Newton, Benjamin Wood, Kieran A Hawkins, Rhys Beddoe, Hannah E Davies, Samuel J Oliver
Dietary nitrate supplementation enhances sea level performance and may ameliorate hypoxemia at high altitude. However, nitrate may exacerbate acute mountain sickness (AMS), specifically headache. This study investigated the effect of nitrate supplementation on AMS symptoms and exercise responses with 6-h hypoxia. Twenty recreationally active men [age, 22 ± 4 yr, maximal oxygen consumption (V̇o2max), 51 ± 6 ml·min(-1)·kg(-1), means ± SD] completed this randomized double-blinded placebo-controlled crossover study...
October 1, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28672774/combinatorial-therapy-of-exercise-preconditioning-and-nanocurcumin-formulation-supplementation-improves-cardiac-adaptation-under-hypobaric-hypoxia
#17
Sarita Nehra, Varun Bhardwaj, Anju Bansal, Deepika Saraswat
BACKGROUND: Chronic hypobaric hypoxia (cHH) mediated cardiac insufficiencies are associated with pathological damage. Sustained redox stress and work load are major causative agents of cardiac insufficiencies under cHH. Despite the advancements made in pharmacological (anti-oxidants, vasodilators) and non-pharmacological therapeutics (acclimatization strategies and schedules), only partial success has been achieved in improving cardiac acclimatization to cHH. This necessitates the need for potent combinatorial therapies to improve cardiac acclimatization at high altitudes...
September 26, 2017: Journal of Basic and Clinical Physiology and Pharmacology
https://www.readbyqxmd.com/read/28640969/control-of-breathing-and-ventilatory-acclimatization-to-hypoxia-in-deer-mice-native-to-high-altitudes
#18
Catherine M Ivy, Graham R Scott
AIM: We compared the control of breathing and heart rate by hypoxia between high- and low-altitude populations of Peromyscus mice, to help elucidate the physiological specializations that help high-altitude natives cope with O2 limitation. METHODS: Deer mice (P. maniculatus) native to high altitude and congeneric mice native to low altitude (P. leucopus) were bred in captivity at sea level. The F1 progeny of each population were raised to adulthood and then acclimated to normoxia or hypobaric hypoxia (12 kPa, simulating hypoxia at ~4300 m) for 5 months...
June 22, 2017: Acta Physiologica
https://www.readbyqxmd.com/read/28590162/exercise-testing-supplemental-oxygen-and-hypoxia
#19
Susan A Ward, Michael P W Grocott, Denny Z H Levett
Cardiopulmonary exercise testing (CPET) in hyperoxia and hypoxia has several applications, stemming from characterization of abnormal physiological response profiles associated with exercise intolerance. As altered oxygenation can impact the performance of gas-concentration and flow sensors and pulmonary gas exchange algorithms, integrated CPET system function requires validation under these conditions. Also, as oxygenation status can influence peak [Formula: see text]o2, care should be taken in the selection of work-rate incrementation rates when CPET performance is to be compared with normobaria at sea level...
July 2017: Annals of the American Thoracic Society
https://www.readbyqxmd.com/read/28506292/normobaric-hypoxia-overnight-impairs-cognitive-reaction-time
#20
Stephan Pramsohler, Stefan Wimmer, Martin Kopp, Hannes Gatterer, Martin Faulhaber, Martin Burtscher, Nikolaus Cristoph Netzer
BACKGROUND: Impaired reaction time in patients suffering from hypoxia during sleep, caused by sleep breathing disorders, is a well-described phenomenon. High altitude sleep is known to induce periodic breathing with central apneas and oxygen desaturations, even in perfectly healthy subjects. However, deficits in reaction time in mountaineers or workers after just some nights of hypoxia exposure are not sufficiently explored. Therefore, we aimed to investigate the impact of sleep in a normobaric hypoxic environment on reaction time divided by its cognitive and motoric components...
May 15, 2017: BMC Neuroscience
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