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acclimatization to high altitude

Maurizio Bussotti, Giovanni Marchese
The effects of hypoxia on the human organism has been considered doubly fascinating by the scientific community: the knowledge of the discrete mechanisms allowing the acclimatization both at the genetic level or through the cell mediators production in addition to the macroscopic responses of the cardio-circulatory and ventilatory systems to a hypoxic environment has been progressively developed since the last century; moreover granting a safer stay in hypoxic conditions not only for the residents but also for the different cathegories of workers, sportsmen and tourists has been considered a worthy aim of the medical activity...
May 17, 2018: Cardiovascular & Hematological Disorders Drug Targets
Douglas T Summerfield, Kirsten E Coffman, Bryan J Taylor, Amine N Issa, Bruce D Johnson
Summerfield, Douglas T., Kirsten E. Coffman, Bryan J. Taylor, Amine N. Issa, and Bruce D. Johnson. Exhaled nitric oxide changes during acclimatization to high altitude: a descriptive study. High Alt Med Biol. 00:000-000, 2018. AIMS: This study describes differences in the partial pressures of exhaled nitric oxide (PeNO) between subjects fully acclimatized (ACC) to 5300 m and those who have just arrived to high altitude. METHODS: PeNO was determined in eight subjects newly exposed and nonacclimatized (non-ACC) to high altitude and compared with that in nine subjects who had ACC to high altitude for 1 month...
May 14, 2018: High Altitude Medicine & Biology
Subhojit Paul, Anamika Gangwar, Kalpana Bhargava, Yasmin Ahmad
Lack of zero side-effect, prescription-less prophylactics and diagnostic markers of acclimatization status lead to many suffering from high altitude illnesses. Although not fully translated to the clinical setting, many strategies and interventions are being developed that are aimed at providing an objective and tangible answer regarding the acclimatization status of an individual as well as zero side-effect prophylaxis that is cost-effective and does not require medical supervision. This short review brings together the twin problems associated with high-altitude acclimatization, i...
April 23, 2018: Life Sciences
Priyanka Dhar, Vijay K Sharma, Saroj K Das, Kalpana Barhwal, Sunil K Hota, Shashi B Singh
We studied the differential responses of autonomic function in sea level residents (SLR), acclimatized lowlanders (ALH) in high altitude (HA) and HA natives (HAN) at >3500 m. Out of 771 male volunteers included in this cross-sectional study, SLR, ALH and HAN groups were comprised of 351, 307 and 113 volunteers, respectively. Our results showed persistent sympathetic dominance with significantly reduced (p < 0.05) parasympathetic response in ALH as compared to SLR and HAN populations. This may be attributed to significantly increased (p < 0...
April 9, 2018: Respiratory Physiology & Neurobiology
Cécile H Kicken, Marisa Ninivaggi, Joke Konings, Martijn Moorlag, Dana Huskens, Jasper A Remijn, Saartje Bloemen, Marcus D Lancé, Bas De Laat
INTRODUCTION:  Epidemiological studies suggest that hypobaric hypoxia at high altitude poses a risk for developing venous thromboembolism. The cause of this observed hypercoagulability remains unclear. Therefore, this study aimed to investigate the effect of hypobaric hypoxia at 3,883 m above sea level on thrombin generation and platelet activation. METHODS:  After complying with medical ethical procedures, 18 participants were recruited, of whom 1 had to leave the study prematurely due to mild acute mountain sickness...
April 3, 2018: Thrombosis and Haemostasis
Martin Burtscher, Michael Philadelphy, Hannes Gatterer, Johannes Burtscher, Rudolf Likar
Annually, thousands of air travellers visit high altitude destinations to enjoy hiking tours to attractions in surrounding areas. However, many of them are not adequately trained, not sufficiently acclimatized and/or may suffer from pre-existing diseases. To prevent adverse health effects and unpleasant experiences at high altitude, simple submaximal exercise testing at low altitude for the prediction of exercise tolerance at high altitude would be helpful. Therefore, 40 healthy males and females performed submaximal exercise tests at low (600 m) and high altitude (3500 m)...
January 1, 2018: Journal of Travel Medicine
Md Saddam Hussain, Vishwas Tripathi
Autoimmune disease management presents a significant challenge to medical science. Environmental factors potentially increase the risk of developing inflammatory and autoimmune diseases, such as multiple sclerosis, rheumatoid arthritis, and lupus. Among various environmental stresses, cigarette smoke and hypoxia have both been reported to lead to an enhanced risk of inflammatory and autoimmune diseases.In this review, we shed light on all reported mechanisms whereby cigarette smoke and a hypoxic environment can induce inflammatory and autoimmune diseases and discuss how hypoxic conditions influence the cigarette smoke-induced threat of inflammatory and autoimmune disease development...
March 30, 2018: Military Medical Research
Hui Du, Jing Zhao, Zhanhai Su, Yongnian Liu, Yingzhong Yang
BACKGROUND: High-altitude pulmonary edema (HAPE) is a serious acute mountain sickness that mainly occurs in non-acclimatized individuals after rapid ascent to high altitude. The precise etiology of HAPE remains unclear. This study aimed to investigate whether NR3C1 gene polymorphism is associated with the susceptibility to HAPE. METHODS: The exons of NR3C1 gene were sequenced by a ABI 3730 DNA analyzer in 133 HAPE patients and matched 135 healthy Han Chinese controls from the Yushu area in Qinghai (the altitude greater than 3500 m)...
March 27, 2018: Journal of Physiological Anthropology
Josefa León-López, Carmen Calderón-Soto, Matías Pérez-Sánchez, Belén Feriche, Xavier Iglesias, Diego Chaverri, Ferran A Rodréguez
Using a controlled parallel group longitudinal trial design, we investigated the effects of different training interventions on the prooxidant/antioxidant status of elite athletes: living and training at moderate altitude for 3 (Hi-Hi3) and 4 weeks (Hi-Hi), and for 4 weeks too, living high and training high and low (Hi-HiLo) and living and training at sea level (Lo-Lo). From 61 swimmers, 54 completed the study. Nitrites, carbonyls, and lipid peroxidation (LPO) levels were assessed in plasma. Enzymatic antioxidants glutathione peroxidase (GPx) and glutathione reductase (GRd), and non-enzymatic antioxidants total glutathione (GST), reduced glutathione (GSH) and oxidized glutathione (GSSG) were analysed in the erythrocyte fraction...
March 24, 2018: European Journal of Sport Science
Ryan L Hoiland, Connor A Howe, Geoff B Coombs, Philip N Ainslie
Ascent to high-altitude elicits compensatory physiological adaptations in order to improve oxygenation throughout the body. The brain is particularly vulnerable to the hypoxemia of terrestrial altitude exposure. Herein we review the ventilatory and cerebrovascular changes at altitude and how they are both implicated in the maintenance of oxygen delivery to the brain. Further, the interdependence of ventilation and cerebral blood flow at altitude is discussed. Following the acute hypoxic ventilatory response, acclimatization leads to progressive increases in ventilation, and a partial mitigation of hypoxemia...
March 24, 2018: Clinical Autonomic Research: Official Journal of the Clinical Autonomic Research Society
Karine C Flor, Elaine F Silva, Miguel F Menezes, Gustavo R Pedrino, Eduardo Colombari, Daniel B Zoccal
Exposure to chronic sustained hypoxia (SH), as experienced in high altitudes, elicits an increase in ventilation, named ventilatory acclimatization to hypoxia (VAH). We previously showed that rats exposed to short-term (24 h) SH exhibit enhanced abdominal expiratory motor activity at rest, accompanied by augmented baseline sympathetic vasoconstrictor activity. In the present study, we investigated whether the respiratory and sympathetic changes elicited by short-term SH are accompanied by carotid body chemoreceptor sensitization...
2018: Frontiers in Physiology
Katie A O'Brien, Ross D Pollock, Mike Stroud, Rob J Lambert, Alex Kumar, Robert A Atkinson, David A Green, Ana Anton-Solanas, Lindsay M Edwards, Steve D R Harridge
An insufficient supply of oxygen to the tissues (hypoxia), as is experienced upon high-altitude exposure, elicits physiological acclimatization mechanisms alongside metabolic remodeling. Details of the integrative adaptive processes in response to chronic hypobaric hypoxic exposure remain to be sufficiently investigated. In this small applied field study, subjects (n = 5, male, age 28-54 years) undertook a 40 week Antarctica expedition in the winter months, which included 24 weeks residing above 2500 m...
March 2018: Physiological Reports
Vivek Vashishtha, Kalpana Kumari Barhwal, Vineet Kumar Malhotra, Ashish Kumar, Sunil Kumar Hota, Tsering Norboo, Om Prakash Chaurasia
Hypoxic exposure at high-altitude (HA) modulates blood pressure (BP). High prevalence of hypertension among native highlanders (NH) has been reported. However, information on prevalence and determinants of hypertension in acclimatized young lowlanders (ALL) staying at HA for different durations is sparse. We aimed to determine the prevalence of hypertension in ALL staying at HA for different durations and its association with cardiovascular risk factors. Male volunteers were categorized on the basis of their duration of stay at HA; Lowlanders (LL) (0 months; n = 151), ALL (1-24 months; n = 519) and NH (n = 103)...
February 26, 2018: Journal of Human Hypertension
P Robach, J Hansen, A Pichon, A-K Meinild Lundby, S Dandanell, G Slettaløkken Falch, D Hammarström, D H Pesta, C Siebenmann, S Keiser, P Kérivel, J E Whist, B R Rønnestad, C Lundby
Live high-train low (LHTL) using hypobaric hypoxia was previously found to improve sea-level endurance performance in well-trained individuals; however, confirmatory controlled data in athletes are lacking. Here, we test the hypothesis that natural-altitude LHTL improves aerobic performance in cross-country skiers, in conjunction with expansion of total hemoglobin mass (Hbmass , carbon monoxide rebreathing technique) promoted by accelerated erythropoiesis. Following duplicate baseline measurements at sea level over the course of 2 weeks, nineteen Norwegian cross-country skiers (three women, sixteen men, age 20 ± 2 year, maximal oxygen uptake (VO2 max) 69 ± 5 mL/min/kg) were assigned to 26 consecutive nights spent at either low (1035 m, control, n = 8) or moderate altitude (2207 m, daily exposure 16...
February 22, 2018: Scandinavian Journal of Medicine & Science in Sports
J Philip Karl, Renee E Cole, Claire E Berryman, Graham Finlayson, Patrick N Radcliffe, Matthew T Kominsky, Nancy E Murphy, John W Carbone, Jennifer C Rood, Andrew J Young, Stefan M Pasiakos
Karl, J. Philip, Renee E. Cole, Claire E. Berryman, Graham Finlayson, Patrick N. Radcliffe, Matthew T. Kominsky, Nancy E. Murphy, John W. Carbone, Jennifer C. Rood, Andrew J. Young, and Stefan M. Pasiakos. Appetite Suppression and Altered Food Preferences Coincide with Changes in Appetite-Mediating Hormones During Energy Deficit at High Altitude, But Are Not Affected by Protein Intake. High Alt Med Biol. 00:000-000, 2018.-Anorexia and unintentional body weight loss are common during high altitude (HA) sojourn, but underlying mechanisms are not fully characterized, and the impact of dietary macronutrient composition on appetite regulation at HA is unknown...
February 12, 2018: High Altitude Medicine & Biology
Alexander B Hansen, Ryan L Hoiland, Nia C S Lewis, Michael M Tymko, Joshua C Tremblay, Michael Stembridge, Daniela Nowak-Flück, Howard H Carter, Damian M Bailey, Philip N Ainslie
NEW FINDINGS: What is the central question of the study? Does the use of antioxidants alter cerebrovascular function and blood flow at sea level (344 m) and/or high altitude (5050 m)? What is the main finding and its importance? This is the first study to investigate whether antioxidant administration alters cerebrovascular regulation and blood flow in response to hypercapnia, acute hypoxia and chronic hypoxia in healthy humans. We demonstrate that an acute dose of antioxidants does not alter cerebrovascular function and blood flow at sea level (344 m) or after 12 days at high altitude (5050 m)...
April 1, 2018: Experimental Physiology
Lorna G Moore
The question of whether human populations have adapted genetically to high altitude has been of interest since studies began there in the early 1900s. Initially there was debate as to whether genetic adaptation to high altitude has taken place based, in part, on disciplinary orientation and the sources of evidence being considered. Studies centered on short-term responses, termed acclimatization, and the developmental changes occurring across lifetimes. A paradigm shift occurred with the advent of single nucleotide polymorphism (SNP) technologies and statistical methods for detecting evidence of natural selection, resulting in an exponential rise in the number of publications reporting genetic adaptation...
December 15, 2017: Quaternary International: the Journal of the International Union for Quaternary Research
José López-Barneo
The carotid body (CB) is the major arterial chemoreceptor responsible for the detection of acute decreases in O2 tension (hypoxia) in arterial blood that trigger hyperventilation and sympathetic activation. The CB contains O2-sensitive glomus (chief) cells, which respond to hypoxia with the release of transmitters to activate sensory nerve fibers impinging upon the brain respiratory and autonomic centers. During exposure to sustained hypoxia (for weeks or months), the CB grows several-fold in size, a response associated with acclimatization to high altitude or to medical conditions presenting hypoxemia...
January 24, 2018: Cell and Tissue Research
Gerardo A Cordero, Bea Angelica Andersson, Jeremie Souchet, Gaëlle Micheli, Daniel W A Noble, Eric J Gangloff, Tobias Uller, Fabien Aubret
Coping with novel environments may be facilitated by plastic physiological responses that enable survival during environmentally sensitive life stages. We tested the capacity for embryos of the common wall lizard (Podarcis muralis) from low altitude to cope with low-oxygen partial pressure (hypoxia) in an alpine environment. Developing embryos subjected to hypoxic atmospheric conditions (15-16% O2 sea-level equivalent) at 2,877 m above sea level exhibited responses common to vertebrates acclimatized to or evolutionarily adapted to high altitude: suppressed metabolism, cardiac hypertrophy, and hyperventilation...
August 2017: Journal of Experimental Zoology. Part A, Ecological and Integrative Physiology
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
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