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acclimatization to high altitude

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https://www.readbyqxmd.com/read/28931132/oxygen-saturation-increases-over-the-course-of-the-night-in-mountaineers-at-high-altitude-3050-6354-m
#1
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
#2
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
#3
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
#4
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
#5
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
#6
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
#7
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
#8
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
#9
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
#10
Gabriella M K Rossetti, Jamie Hugo Macdonald, Lee J Wylie, Samuel J Little, Victoria Newton, Benjamin Wood, Kieran A Hawkins, Rhys Beddoe, Hannah E Davies, Samuel James 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 6h hypoxia. Twenty recreationally-active men (mean(SD): age 22(4) years, V̇O2max 51(6) mL·min-1·kg-1) completed this randomized double-blinded placebo-controlled crossover study. Twelve participants were classified as AMS- based on Environmental Symptom Questionnaire (AMS-C) score <0...
July 6, 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
#11
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
#12
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
#13
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
#14
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
https://www.readbyqxmd.com/read/28486083/progress-in-mass-spectrometry-based-proteomics-in-hypoxia-related-diseases-and-high-altitude-medicine
#15
Zhiqi Gao, Gang Luo, Bing Ni
Human migration, influenced by social conflict and natural disasters as well as global climate change, has become recognized as a major "planetary force." It has also brought to the forefront, new specialties of integrative biology-such as high-altitude medicine-and the impact of hitherto understudied environmental factors on human pathophysiology in these new geographical settings. For people migrating to or living in high-altitude regions, environmental hypoxia is a primary challenge. Decreased partial pressure of oxygen in environmental air, caused by lower barometric pressure, puts living organisms in a hypoxic state...
June 2017: Omics: a Journal of Integrative Biology
https://www.readbyqxmd.com/read/28486037/role-of-arcuate-nucleus-in-the-regulation-of-feeding-behavior-in-the-process-of-altitude-acclimatization-in-rats
#16
Xiang-Wen Liu, Jie Yin, Qi-Sheng Ma, Chu-Chu Qi, Ji-Ying Mu, Lang Zhang, Li-Ping Gao, Yu-Hong Jing
Liu, Xiang-Wen, Jie Yin, Qi-Sheng Ma, Chu-Chu Qi, Ji-Ying Mu, Lang Zhang, Li-Ping Gao, and Yu-Hong Jing. Role of arcuate nucleus in the regulation of feeding behavior in the process of altitude acclimatization in rats. High Alt Med Biol. 18:234-241, 2017.-Highly efficient energy utilization and metabolic homeostasis maintenance rely on neuromodulation. Altitude exposure is known to stimulate neuroendocrine systems to respond to acute hypoxia and adaptive acclimatization. However, limited data on how the adaptive regulation of the arcuate nucleus performs in the process of altitude acclimatization are available...
September 2017: High Altitude Medicine & Biology
https://www.readbyqxmd.com/read/28453332/long-term-intermittent-exposure-to-high-altitude-elevates-asymmetric-dimethylarginine-in-first-exposed-young-adults
#17
Nicole Lüneburg, Patricia Siques, Julio Brito, Juan José De La Cruz, Fabiola León-Velarde, Juliane Hannemann, Cristian Ibanez, Rainer H Böger
Lüneburg, Nicole, Patricia Siques, Julio Brito, Juan José De La Cruz, Fabiola León-Velarde, Juliane Hannemann, Cristian Ibanez, and Rainer Böger. Long-term intermittent exposure to high altitude elevates asymmetric dimethylarginine in first exposed young adults. High Alt Med Biol. 18:226-233, 2017.-Hypoxia-induced dysregulation of pulmonary and cerebral circulation may be related to an impaired nitric oxide (NO) pathway. We investigated the effect of chronic intermittent hypobaric hypoxia (CIH) on metabolites of the NO pathway...
September 2017: High Altitude Medicine & Biology
https://www.readbyqxmd.com/read/28418725/medex-2015-heart-rate-variability-predicts-development-of-acute-mountain-sickness
#18
Angus Sutherland, Joseph Freer, Laura Evans, Alberto Dolci, Matteo Crotti, Jamie Hugo Macdonald
Sutherland, Angus, Joseph Freer, Laura Evans, Alberto Dolci, Matteo Crotti, and Jamie Hugo Macdonald. MEDEX 2015: Heart rate variability predicts development of acute mountain sickness. High Alt Med Biol. 18: 199-208, 2017. AIMS: Acute mountain sickness (AMS) develops when the body fails to acclimatize to atmospheric changes at altitude. Preascent prediction of susceptibility to AMS would be a useful tool to prevent subsequent harm. Changes to peripheral oxygen saturation (SpO2) on hypoxic exposure have previously been shown to be of poor predictive value...
September 2017: High Altitude Medicine & Biology
https://www.readbyqxmd.com/read/28389828/cross-adaptation-heat-and-cold-adaptation-to-improve-physiological-and-cellular-responses-to-hypoxia
#19
REVIEW
Oliver R Gibson, Lee Taylor, Peter W Watt, Neil S Maxwell
To prepare for extremes of heat, cold or low partial pressures of oxygen (O2), humans can undertake a period of acclimation or acclimatization to induce environment-specific adaptations, e.g. heat acclimation (HA), cold acclimation (CA), or altitude training. While these strategies are effective, they are not always feasible due to logistical impracticalities. Cross-adaptation is a term used to describe the phenomenon whereby alternative environmental interventions, e.g. HA or CA, may be a beneficial alternative to altitude interventions, providing physiological stress and inducing adaptations observable at altitude...
April 7, 2017: Sports Medicine
https://www.readbyqxmd.com/read/28375664/effects-of-short-term-acclimatization-at-the-summit-of-mt-fuji-3776%C3%A2-m-on-sleep-efficacy-cardiovascular-responses-and-ventilatory-responses
#20
Masahiro Horiuchi, Shiro Oda, Tadashi Uno, Junko Endo, Yoko Handa, Yoshiyuki Fukuoka
Horiuchi, Masahiro, Shiro Oda, Tadashi Uno, Junko Endo, Yoko Handa, and Yoshiyuki Fukuoka. Effects of short-term acclimatization at the summit of Mt. Fuji (3776 m) on sleep efficacy, cardiovascular responses, and ventilatory responses. High Alt Med Biol. 18:171-178, 2017.-We investigated the effects of a short period of acclimatization, at 3776 m on Mt. Fuji, on sleep parameters and related physiological responses. Physiological responses were assessed in seven healthy lowlander men during both daytime and sleep while at sea level (SL), as well as for three consecutive nights at high altitude (HA; 3776 m, day 1 [D1], D2, D3, and morning only of D4)...
June 2017: High Altitude Medicine & Biology
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