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acclimatization to high altitude

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https://www.readbyqxmd.com/read/28798201/remote-ischemic-preconditioning-does-not-prevent-acute-mountain-sickness-after-rapid-ascent-to-3450-m
#1
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
#2
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
#3
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
#4
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
#5
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...
June 16, 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
#6
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
#7
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
#8
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
#9
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
#10
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. 00:000-000, 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...
May 9, 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
#11
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 00:000-000, 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...
April 28, 2017: High Altitude Medicine & Biology
https://www.readbyqxmd.com/read/28418725/medex-2015-heart-rate-variability-predicts-development-of-acute-mountain-sickness
#12
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 00:000-000, 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...
April 18, 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
#13
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
#14
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
https://www.readbyqxmd.com/read/28372260/preliminary-investigation-for-effects-of-hypothalamic-leptin-ghrelin-and-arcuate-nucleus-pro-opiomelanocortin-system-on-regulation-of-high-altitude-acclimatization
#15
Yong-Nian Liu, Qi-Sheng Ma, Qiong Wu
This study aims to investigate the mechanism of hypothalamic Leptin/Ghrelin and arcuate nucleus pro-opiomelanocortin (POMC) system in the regulation of high-altitude acclimatization. SD rats (male) were divided into two groups and separately fed at the 2260m and 4700m altitude. Tow groups contained 5 small groups separately, including 1 d, 3 d, 7 d, 15 d and 30 d, and 8 rats in each group. Blood, cerebrospinal fluid and tissues were taken at setting time. Leptin and Ghrelin were detected by using radioactivity immuno-assay...
May 2017: Biomedicine & Pharmacotherapy, Biomédecine & Pharmacothérapie
https://www.readbyqxmd.com/read/28370674/reduced-blood-flow-through-intrapulmonary-arteriovenous-anastomoses-during-exercise-in-lowlanders-acclimatizing-to-high-altitude
#16
Lindsey M Boulet, Andrew T Lovering, Michael M Tymko, Trevor A Day, Mike Stembridge, Trang Anh Nguyen, Philip N Ainslie, Glen E Foster
What is the central question of this study? The aim was to determine, using the technique of agitated saline contrast echocardiography, whether exercise after 4-7 days at 5050 m would affect blood flow through intrapulmonary arteriovenous anastomoses (Q̇IPAVA) compared with exercise at sea level. What is the main finding and its importance? Despite a significant increase in both cardiac output and pulmonary pressure during exercise at high altitude, there is very little Q̇IPAVA at rest or during exercise after 4-7 days of acclimatization...
March 30, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28239483/soldiers-load-carriage-performance-in-high-mountains-a-physiological-study
#17
Tirthankar Chatterjee, Debojyoti Bhattacharyya, Anilendu Pramanik, Madhusudan Pal, Deepti Majumdar, Dhurjati Majumdar
BACKGROUND: The present study was designed to evaluate load carriage performance at extremely high altitudes with different loads and walking speeds in terms of physiological evaluation. The degree of maximum oxygen consumption changes at high altitudes was also examined. METHODS: Twelve Indian Army soldiers were acclimatized at altitudes of 3,505 m and 4,300 m. They walked for 10 minutes on a motorized treadmill at 2.5 km/h and 3.5 km/h speeds during carrying no loads and three magnitudes of load (10...
2017: Military Medical Research
https://www.readbyqxmd.com/read/28169986/erythrocytes-retain-hypoxic-adenosine-response-for-faster-acclimatization-upon-re-ascent
#18
Anren Song, Yujin Zhang, Leng Han, Gennady G Yegutkin, Hong Liu, Kaiqi Sun, Angelo D'Alessandro, Jessica Li, Harry Karmouty-Quintana, Takayuki Iriyama, Tingting Weng, Shushan Zhao, Wei Wang, Hongyu Wu, Travis Nemkov, Andrew W Subudhi, Sonja Jameson-Van Houten, Colleen G Julian, Andrew T Lovering, Kirk C Hansen, Hong Zhang, Mikhail Bogdanov, William Dowhan, Jianping Jin, Rodney E Kellems, Holger K Eltzschig, Michael Blackburn, Robert C Roach, Yang Xia
Faster acclimatization to high altitude upon re-ascent is seen in humans; however, the molecular basis for this enhanced adaptive response is unknown. We report that in healthy lowlanders, plasma adenosine levels are rapidly induced by initial ascent to high altitude and achieved even higher levels upon re-ascent, a feature that is positively associated with quicker acclimatization. Erythrocyte equilibrative nucleoside transporter 1 (eENT1) levels are reduced in humans at high altitude and in mice under hypoxia...
February 7, 2017: Nature Communications
https://www.readbyqxmd.com/read/28149350/the-influence-of-high-altitude-acclimatization-on-ventilatory-and-blood-oxygen-saturation-responses-during-normoxic-and-hypoxic-testing
#19
Anton Ušaj, Stojan Burnik
We investigated how acclimatization effects achieved during a high-altitude alpinist expedition influence endurance performance, ventilation ([Formula: see text]) and blood oxygen saturation (SaO2) in normoxic (NOR) and hypoxic conditions (HYP). An incremental testing protocol on a cycle ergometer was used to determine the power output corresponding to the Lactate (PLT) and Ventilatory Threshold (PVT) in NOR and HYP (FiO2=0.13) as indirect characteristics of endurance performance in both conditions. Furthermore, changes in [Formula: see text], SaO2, blood pH and Pco2 were measured at a similar absolute exercise intensity of 180 W in NOR and HYP conditions...
April 1, 2016: Journal of Human Kinetics
https://www.readbyqxmd.com/read/28032333/the-effect-of-%C3%AE-1-adrenergic-blockade-on-post-exercise-brachial-artery-flow-mediated-dilatation-at-sea-level-and-high-altitude
#20
Michael M Tymko, Joshua C Tremblay, Alex B Hansen, Connor A Howe, Chris K Willie, Mike Stembridge, Daniel J Green, Ryan L Hoiland, Prajan Subedi, James D Anholm, Philip N Ainslie
KEY POINTS: Our objective was to quantify endothelial function (via brachial artery flow-mediated dilatation) at sea level (344 m) and high altitude (3800 m) at rest and following both maximal exercise and 30 min of moderate-intensity cycling exercise with and without administration of an α1 -adrenergic blockade. Brachial endothelial function did not differ between sea level and high altitude at rest, nor following maximal exercise. At sea level, endothelial function decreased following 30 min of moderate-intensity exercise, and this decrease was abolished with α1 -adrenergic blockade...
March 1, 2017: Journal of Physiology
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