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acclimatization to high altitude

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https://www.readbyqxmd.com/read/27888818/high-altitude-illness
#1
Anna Hartman-Ksycińska, Jolanta Kluz-Zawadzka, Bogumił Lewandowski
High-altitude illness is a result of prolonged high-altitude exposure of unacclimatized individuals. The illness is seen in the form of acute mountain sickness (AMS) which if not treated leads to potentially life-threatening high altitude pulmonary oedema and high-altitude cerebral oedema. Medical problems are caused by hypobaric hypoxia stimulating hypoxia-inducible factor (HIF) release. As a result, the central nervous system, circulation and respiratory system function impairment occurs. The most important factor in AMS treatment is acclimatization, withdrawing further ascent and rest or beginning to descent; oxygen supplementation, and pharmacological intervention, and, if available, a portable hyperbaric chamber...
2016: Przegla̧d Epidemiologiczny
https://www.readbyqxmd.com/read/27793615/seasonal-variation-of-metabolism-in-lizard-phrynocephalus-vlangalii-at-high-altitude
#2
Shiwei Liang, Weixin Li, Yang Zhang, Xiaolong Tang, Jianzheng He, Yucheng Bai, Dongqin Li, Yan Wang, Qiang Chen
Seasonal acclimatization is important for animals to live optimally in the varying environment. Phrynocephalus vlangalii, a species of lizard endemic in China, distributes on Qinghai-Tibet Plateau ranging from 2000 to 4600m above sea level. To dissect how this lizard mediate metabolism to adapt various season, the preferred body temperature (Tb), standard metabolic rate (SMR), mitochondrial respiration rates and activities of four metabolic enzymes in this species were tested in different seasons (spring, summer, and autumn)...
October 26, 2016: Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology
https://www.readbyqxmd.com/read/27754698/effect-of-increased-blood-flow-on-pulmonary-circulation-before-and-during-high-altitude-acclimatization
#3
Matthias Peter Hilty, Andrea Müller, Daniela Flück, Christoph Siebenmann, Peter Rasmussen, Stefanie Keiser, Katja Auinger, Carsten Lundby, Marco Maggiorini
: Matthias Peter Hilty, Andrea Mueller, Daniela Flück, Christoph Siebenmann, Peter Rasmussen, Stefanie Keiser, Katja Auinger, Carsten Lundby, and Marco Maggiorini. Effect of increased blood flow on the pulmonary circulation before and during high altitude acclimatization. High Alt Med Biol. 00:000-000, 2016.-Introduction and Methods: Acute exposure to high altitude increases pulmonary artery pressure (Ppa) and pulmonary vascular resistance (PVR). The evolution of Ppa and PVR with continuous hypoxic exposure remains, however, elusive...
October 18, 2016: High Altitude Medicine & Biology
https://www.readbyqxmd.com/read/27688941/long-term-acclimatization-to-high-altitude-hypoxia-modifies-interhemispheric-functional-and-structural-connectivity-in-the-adult-brain
#4
Ji Chen, Jinqiang Li, Qiaoqing Han, Jianzhong Lin, Tianhe Yang, Ziqian Chen, Jiaxing Zhang
BACKGROUND: Structural and functional networks can be reorganized to adjust to environmental pressures and physiologic changes in the adult brain, but such processes remain unclear in prolonged adaptation to high-altitude (HA) hypoxia. This study aimed to characterize the interhemispheric functionally and structurally coupled modifications in the brains of adult HA immigrants. METHODS: We performed resting-state functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) in 16 adults who had immigrated to the Qinghai-Tibet Plateau (2300-4400 m) for 2 years and in 16 age-matched sea-level (SL) controls...
September 2016: Brain and Behavior
https://www.readbyqxmd.com/read/27643447/the-adrenocortical-response-to-synthetic-acth-following-a-trek-to-high-altitude
#5
J Mackey, A Mellor, J Watchorn, A Burnett, C Boot, D Woods
Gradual ascent to high altitude is typically associated with reduced resting aldosterone and unchanged cortisol, features that may facilitate acclimatization but are poorly understood. The aim of the study was to investigate the cortisol and aldosterone response to adrenocorticotrophic hormone at altitude. Eleven subjects underwent a 250 μg short synacthen test at sea-level and again after trekking to 3 600 m in Nepal. Cortisol and aldosterone were measured by conventional assay from blood samples taken immediately prior to the administration of synacthen (T0) and then 30 (T30) and 60 (T60) min later...
September 2016: Hormone and Metabolic Research, Hormon- und Stoffwechselforschung, Hormones et Métabolisme
https://www.readbyqxmd.com/read/27622961/yoga-practice-improves-physiological-and-biochemical-status-at-high-altitudes-a-prospective-case-control-study
#6
Gidugu Himashree, Latika Mohan, Yogesh Singh
UNLABELLED: Context • High altitude (HA) is a psychophysiological stressor for natives of lower altitudes. Reducing the morbidity and optimizing the performance of individuals deployed in an HA region has been attempted and reported with varied results. Objective • The present study intended to explore the effects of comprehensive yogic practices on the health and performance of Indian soldiers deployed at HAs. Design • The research team designed a prospective, randomized, case-control study...
September 2016: Alternative Therapies in Health and Medicine
https://www.readbyqxmd.com/read/27601532/fulminant-high-altitude-blindness
#7
Evgeny Mashkovskiy, Piotr Szawarski, Pavel Ryzhkov, Tomaz Goslar, Irena Mrak
Prolonged altitude exposure even with acclimatization continues to present a physiological challenge to all organ systems including the central nervous system. We describe a case of a 41-year-old Caucasian female climber who suffered severe visual loss that was due to possible optic nerve pathology occurring during a high altitude expedition in the Himalayas. This case is atypical of classic high altitude cerebral oedema and highlights yet another danger of prolonged sojourn at extreme altitudes.
June 2016: Journal of Travel Medicine
https://www.readbyqxmd.com/read/27575244/high-altitude-pulmonary-edema-without-appropriate-action-progresses-to-right-ventricular-strain-a-case-study
#8
Logan Mills, Chris Harper, Sophie Rozwadowski, Chris Imray
Mills, Logan, Chris Harper, Sophie Rozwadowski, and Chris Imray. High altitude pulmonary edema without appropriate action progresses to right ventricular strain: A case study. High Alt Med Biol. 17:228-232, 2016.-A 24-year-old male developed high altitude pulmonary edema (HAPE) after three ascents to 4061 m over 3 days, sleeping each night at 2735 m. He complained of exertional dyspnea, dry cough, chest pain, fever, nausea, vertigo, and a severe frontal headache. Inappropriate continuation of ascent despite symptoms led to functional impairment and forced a return to the valley, but dyspnea persisted in addition to new orthopnea...
September 2016: High Altitude Medicine & Biology
https://www.readbyqxmd.com/read/27548274/brief-working-memory-and-physiological-monitoring-during-a-high-altitude-expedition
#9
Carine Malle, Benoît Ginon, Cyprien Bourrilhon
: Malle, Carine, Benoît Ginon, and Cyprien Bourrilhon. Brief working memory and physiological monitoring during a high-altitude expedition. High Alt Med Biol 00:000-000, 2016. BACKGROUND: Various studies have shown the deleterious effects of high-altitude hypoxia on cognitive functions, including attention and memory. Since optimal cognitive abilities may be crucial for mountain safety, this study was aimed to assess the relevance of a brief working memory test to quickly assess cognition at high altitude...
August 22, 2016: High Altitude Medicine & Biology
https://www.readbyqxmd.com/read/27421182/characteristics-of-eeg-activity-during-high-altitude-hypoxia-and-lowland-reoxygenation
#10
Jin-Ping Zhao, Ran Zhang, Qian Yu, Jia-Xing Zhang
The aim of the present study was to determine the effect of high altitude (HA) immigration on cerebral electrical activity. Electro-EncephaloGraphic (EEG) activity were recorded from 25 lowland soldiers during eyes-closed resting conditions under the following conditions: 7 days at lowland before ascending to altitude (Test 1), during the first 7 days (Test 2) and 30 days (Test 3) at 3800m altitude, and 7 days after return to lowland (Test 4). The EEG was Fourier transformed to provide absolute and relative power estimates for the alpha, beta, delta, and theta bands...
October 1, 2016: Brain Research
https://www.readbyqxmd.com/read/27418686/physiological-impact-of-patent-foramen-ovale-on-pulmonary-gas-exchange-ventilatory-acclimatization-and-thermoregulation
#11
REVIEW
Andrew T Lovering, Jonathan E Elliott, James T Davis
The foramen ovale, which is part of the normal fetal cardiopulmonary circulation, fails to close after birth in ∼35% of the population and represents a potential source of right-to-left shunt. Despite the prevalence of patent foramen ovale (PFO) in the general population, cardiopulmonary, exercise, thermoregulatory, and altitude physiologists may have underestimated the potential effect of this shunted blood flow on normal physiological processes in otherwise healthy humans. Because this shunted blood bypasses the respiratory system, it would not participate in either gas exchange or respiratory system cooling and may have impacts on other physiological processes that remain undetermined...
August 1, 2016: Journal of Applied Physiology
https://www.readbyqxmd.com/read/27414687/seven-passive-1-h-hypoxia-exposures-do-not-prevent-ams-in-susceptible-individuals
#12
Martin Faulhaber, Elena Pocecco, Hannes Gatterer, Martin Niedermeier, Maike Huth, Tobias Dünnwald, Verena Menz, Luciano Bernardi, Martin Burtscher
PURPOSE: The present study evaluated the effects of a pre-acclimatization program comprising 7 passive 1-hour exposures to 4,500 m normobaric hypoxia on the prevalence and severity of acute mountain sickness (AMS) during a subsequent exposure to real high altitude in persons susceptible to AMS. METHODS: The project was designed as a randomized controlled trial including 32 healthy female and male participants with known susceptibility to AMS symptoms. After baseline measurements participants were randomly assigned to the hypoxia or the control group to receive the pre-acclimatization program (7 passive 1-hour exposures within 7 days to normobaric hypoxia or sham hypoxia)...
July 12, 2016: Medicine and Science in Sports and Exercise
https://www.readbyqxmd.com/read/27343109/does-the-sympathetic-nervous-system-adapt-to-chronic-altitude-exposure
#13
Mikael Sander
During continued exposure to hypobaric hypoxia in acclimatizing lowlanders increasing norepinephrine levels indirectly indicate sympathoexcitation, and in a few subjects serial measurements have suggested some adaptation over time. A few studies have provided direct microneurographic evidence for markedly increased muscle sympathetic nervous activity (MSNA) after 1-50 days of exposure of lowlanders to altitudes of 4100-5260 m above sea level. Only one study has provided two MSNA-measurements over time (10 and 50 days) in altitude (4100 m above sea level) and continued robust sympathoexcitation without adaptation was found in acclimatizing lowlanders...
2016: Advances in Experimental Medicine and Biology
https://www.readbyqxmd.com/read/27343108/hemoglobin-mass-and-aerobic-performance-at-moderate-altitude-in-elite-athletes
#14
Jon Peter Wehrlin, Bernard Marti, Jostein Hallén
Fore more than a decade, the live high-train low (LHTL) approach, developed by Levine and Stray-Gundersen, has been widely used by elite endurance athletes. Originally, it was pointed out, that by living at moderate altitude, athletes should benefit from an increased red cell volume (RCV) and hemoglobin mass (Hbmass), while the training at low altitudes should prevent the disadvantage of reduced training intensity at moderate altitude. VO2max is reduced linearly by about 6-8 % per 1000 m increasing altitude in elite athletes from sea level to 3000 m, with corresponding higher relative training intensities for the same absolute work load...
2016: Advances in Experimental Medicine and Biology
https://www.readbyqxmd.com/read/27343103/central-sleep-apnea-at-high-altitude
#15
Keith R Burgess, Philip N Ainslie
The discovery of central sleep apnea (CSA) at high altitude is usually attributed to Angelo Mosso who published in 1898. It can occur in susceptible individuals at altitude above 2000 m, but at very high altitude, say above 5000 m, it will occur in most subjects. Severity is correlated with ventilatory responsiveness, particularly to hypoxia. Theoretically, it should spontaneously improve with time and acclimatization. Although the time course of resolution is not well described, it appears to persist for more than a month at 5000 m...
2016: Advances in Experimental Medicine and Biology
https://www.readbyqxmd.com/read/27343089/why-are-high-altitude-natives-so-strong-at-altitude-maximal-oxygen-transport-to-the-muscle-cell-in-altitude-natives
#16
Carsten Lundby, Jose A L Calbet
In hypoxia aerobic exercise performance of high-altitude natives is suggested to be superior to that of lowlanders; i.e., for a given altitude natives are reported to have higher maximal oxygen uptake (VO2max). The likely basis for this is a higher pulmonary diffusion capacity, which in turn ensures higher arterial O2 saturation (SaO2) and therefore also potentially a higher delivery of O2 to the exercising muscles. This review focuses on O2 transport in high-altitude Aymara. We have quantified femoral artery O2 delivery, arterial O2 extraction and calculated leg VO2 in Aymara, and compared their values with that of acclimatizing Danish lowlanders...
2016: Advances in Experimental Medicine and Biology
https://www.readbyqxmd.com/read/27322318/dietary-recommendations-for-cyclists-during-altitude-training
#17
REVIEW
Małgorzata Michalczyk, Miłosz Czuba, Grzegorz Zydek, Adam Zając, Józef Langfort
The concept of altitude or hypoxic training is a common practice in cycling. However, several strategies for training regimens have been proposed, like "live high, train high" (LH-TH), "live high, train low" (LH-TL) or "intermittent hypoxic training" (IHT). Each of them combines the effect of acclimatization and different training protocols that require specific nutrition. An appropriate nutrition strategy and adequate hydration can help athletes achieve their fitness and performance goals in this unfriendly environment...
2016: Nutrients
https://www.readbyqxmd.com/read/27126783/transcriptomic-plasticity-in-brown-adipose-tissue-contributes-to-an-enhanced-capacity-for-nonshivering-thermogenesis-in-deer-mice
#18
Jonathan P Velotta, Jennifer Jones, Cole J Wolf, Zachary A Cheviron
For small mammals living at high altitude, aerobic heat generation (thermogenesis) is essential for survival during prolonged periods of cold, but is severely impaired under conditions of hypobaric hypoxia. Recent studies in deer mice (Peromyscus maniculatus) reveal adaptive enhancement of thermogenesis in high- compared to low-altitude populations under hypoxic cold stress, an enhancement that is attributable to modifications in the aerobic metabolism of muscles used in shivering. However, because small mammals rely heavily on nonshivering mechanisms for cold acclimatization, we tested for evidence of adaptive divergence in nonshivering thermogenesis (NST) under hypoxia...
June 2016: Molecular Ecology
https://www.readbyqxmd.com/read/27120676/bicarbonate-values-for-healthy-residents-living-in-cities-above-1500-meters-of-altitude-a-theoretical-model-and-systematic-review
#19
Juan C Ramirez-Sandoval, Maria F Castilla-Peón, José Gotés-Palazuelos, Juan C Vázquez-García, Michael P Wagner, Carlos A Merelo-Arias, Olynka Vega-Vega, Rodolfo Rincón-Pedrero, Ricardo Correa-Rotter
Ramirez-Sandoval, Juan C., Maria F. Castilla-Peón, José Gotés-Palazuelos, Juan C. Vázquez-García, Michael P. Wagner, Carlos A. Merelo-Arias, Olynka Vega-Vega, Rodolfo Rincón-Pedrero, and Ricardo Correa-Rotter. Bicarbonate values for healthy residents living in cities above 1500 m of altitude: a theoretical model and systematic review. High Alt Med Biol. 17:85-92, 2016.-Plasma bicarbonate (HCO3(-)) concentration is the main value used to assess the metabolic component of the acid-base status. There is limited information regarding plasma HCO3(-) values adjusted for altitude for people living in cities at high altitude defined as 1500 m (4921 ft) or more above sea level...
June 2016: High Altitude Medicine & Biology
https://www.readbyqxmd.com/read/26984355/biomarkers-of-hypoxia-endothelial-and-circulatory-dysfunction-among-climbers-in-nepal-with-ams-and-hape-a-prospective-case-control-study
#20
Kevin R Barker, Andrea L Conroy, Michael Hawkes, Holly Murphy, Prativa Pandey, Kevin C Kain
BACKGROUND: The mechanisms underlying acute mountain sickness (AMS) and high-altitude pulmonary edema (HAPE) are not fully understood. We hypothesized that regulators of endothelial function, circulatory homeostasis, hypoxia and cell stress contribute to the pathobiology of AMS and HAPE. METHODS: We conducted a prospective case-control study of climbers developing altitude illness who were evacuated to the CIWEC clinic in Kathmandu, compared to healthy acclimatized climbers...
March 2016: Journal of Travel Medicine
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