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Joshua C Tremblay, Connor A Howe, Philip N Ainslie, Kyra Ellen Pyke
Experimentally-induced oscillatory shear stress (OSS) and hypoxia reduce endothelial function in humans. Acute and sustained hypoxia may cause increases in resting OSS; however, whether this influences endothelial susceptibility to further increases in OSS is unknown. Healthy lowlanders (n=15, 30{plus minus}6 years [mean{plus minus}SD]) participated in three OSS interventions; two at sea level (normoxia and following 20-minutes of normobaric hypoxia [acute hypoxia, 11% O2 ]) and one 5-7 days after a 9-day ascent to 5050m (sustained hypoxia)...
March 9, 2018: American Journal of Physiology. Heart and Circulatory Physiology
Aleksandra Żebrowska, Barbara Hall, Aleksandra Kochańska-Dziurowicz, Grażyna Janikowska
BACKGROUND: An integral part of the treatment of diabetes is physical activity. Scientific reports have shown the beneficial effects of hypoxia and exercise on cardiovascular and metabolic variables in patients with diabetes. OBJECTIVES: The aim of the study was to assess the effect of normobaric hypoxia and exercise on the serum concentrations of proangiogenic factors and glycemia in patients with type 1 diabetes. MATERIAL AND METHODS: A total of 28 adults (aged 30...
February 2018: Advances in Clinical and Experimental Medicine: Official Organ Wroclaw Medical University
Stéphane Doutreleau, Irina Enache, Cristina Pistea, Bernard Geny, Anne Charloux
In this study, we hypothesized that adding CO2 to an inhaled hypoxic gas mixture will limit the rise of pulmonary artery pressure (PAP) induced by a moderate exercise. Eight 20-year-old males performed four constant-load exercise tests on cycle at 40% of maximal oxygen consumption in four conditions: ambient air, normobaric hypoxia (12.5% O2 ), inhaled CO2 (4.5% CO2 ), and combination of hypoxia and inhaled CO2 . Doppler echocardiography was used to measure systolic (s)PAP, cardiac output (CO). Total pulmonary resistance (TPR) was calculated...
March 3, 2018: Pflügers Archiv: European Journal of Physiology
Ira Katz, Jacqueline Murdock, Marc Palgen, Géraldine Farjot
Under normal conditions we continuously breathe 78% nitrogen (N2 ) such that the body tissues and fluids are saturated with dissolved N2 . For normobaric medical gas administration at high concentrations, the N2 concentration must be less than that in the ambient atmosphere; therefore, nitrogen will begin to be released by the body tissues. There is a need to estimate the time needed for denitrogenation in the planning of surgical procedures. In this paper we will describe the application of a physiologically based pharmacokinetic model to denitrogenation kinetics...
October 2017: Medical Gas Research
Julien Vincent Brugniaux, Geoff B Coombs, Otto F Barak, Zeljko Dujic, Mypinder S Sekhon, Philip N Ainslie
Molecular oxygen (O2 ) is a vital element in human survival and plays a major role in a diverse range of biological and physiological processes. Although normobaric hyperoxia can increase arterial oxygen content (CaO2 ), it also causes vasoconstriction and hence reduces O2 delivery in various vascular beds including the heart, skeletal muscle, and brain. Thus, a seemingly paradoxical situation exists in which the administration of oxygen may place tissues at increased risk of hypoxic stress. Nevertheless, with various degrees of effectiveness, and not without consequences, supplemental oxygen is used clinically in an attempt to correct tissue hypoxia (e...
February 28, 2018: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
Gang Bai, Bin Yang, Weimin Tong, Hongjun Li
The effect of hypoxia on the spermatogenesis of male Wistar rats (n = 32) at pre-puberty was studied using a hypobaric chamber simulating an altitude of 5,000 metres above sea level. Persistent hypoxic exposure with brief interruption for 3 weeks caused significant decreases in body and testis weights and testosterone level compared to the normobaric controls. Histologically, spermatogenic development was arrested; arrays of spermatids were misshaped; numbers of spermatogonia, Sertoli and Leydig cells were reduced; and apoptotic spermatocytes were increased substantially in the germinal epithelium of testis in the hypoxic-exposed group...
February 27, 2018: Andrologia
Bob Smit, Yvo M Smulders, Johannes C van der Wouden, Heleen M Oudemans-van Straaten, Angelique M E Spoelstra-de Man
BACKGROUND: In clinical practice, oxygen is generally administered to patients with the intention of increasing oxygen delivery. Supplemental oxygen may, however, cause arterial hyperoxia, which is associated with hemodynamic alterations. We performed a systematic review and meta-analysis of the literature to determine the effect of hyperoxia on central hemodynamics and oxygen delivery in healthy volunteers and cardiovascular-compromised patients. METHODS: PubMed and EMBASE were searched up to March 2017...
February 25, 2018: Critical Care: the Official Journal of the Critical Care Forum
Alba Camacho-Cardenosa, Marta Camacho-Cardenosa, Martin Burtscher, Ismael Martínez-Guardado, Rafael Timon, Javier Brazo-Sayavera, Guillermo Olcina
A moderate hypoxic stimulus is considered a promising therapeutic modality for several pathological states including obesity. There is scientific evidence suggesting that when hypoxia and physical activity are combined, they could provide benefits for the obese population. The aim of the present study was to investigate if exposure to hypoxia combined with two different protocols of high-intensity interval exercise in overweight/obese women was more effective compared with exercise in normoxia. Study participants included 82 overweight/obese women, who started a 12 week program of 36 sessions, and were randomly divided into four groups: (1) aerobic interval training in hypoxia (AitH; FiO2 = 17...
2018: Frontiers in Physiology
Nektarios A M Stavrou, Tadej Debevec, Ola Eiken, Igor B Mekjavic
Hypoxia and confinement have both been shown to influence emotional state. It is envisaged that the inhabitants of future planetary habitats will be exposed to concomitant confinement, reduced gravity and hypoxia. We examined the independent and combined effects of a 21-day inactivity/unloading and normobaric hypoxia under confined conditions on various psychological factors. Eleven healthy men participated in three 21-day experimental campaigns designed in a cross-over manner: (1) Normobaric hypoxic ambulatory confinement, (2) Normobaric hypoxic bed rest and (3) Normobaric normoxic bed rest...
2018: Frontiers in Physiology
Bimit Mahat, Étienne Chassé, Clare Lindon, Jean-François Mauger, Pascal Imbeault
Circulating fatty acids are a major systemic energy source in the fasting state as well as a determinant of hepatic triglyceride (TG)-rich very low-density lipoprotein (VLDL) production. Upon acute hypoxia, sympathetic arousal induces adipose tissue lipolysis, resulting in an increase in circulating non-esterified fatty acids (NEFA). Animal studies suggest that TG clearance may also be strongly reduced under hypoxia, though this effect has been shown to be dependent on temperature. Whether the hypoxia-induced rise in blood fatty acid concentrations effects fasting TG levels in humans under thermoneutral conditions remains unknown...
February 21, 2018: Applied Physiology, Nutrition, and Metabolism, Physiologie Appliquée, Nutrition et Métabolisme
Qin Yang, Guoyuan Huang, Qianqian Tian, Wei Liu, Xiangdong Sun, Na Li, Shunli Sun, Tang Zhou, Nana Wu, Yuqin Wei, Peijie Chen, Ru Wang
BACKGROUND: "Living High-Training Low" (LHTL) is effective for the improvement of athletic ability; however, little is known about the effect of LHTL on obese individuals. The present study determined whether LHTL would have favorable influence on body composition, rebalance the appetite hormones, and explore the underlying mechanism. METHODS: Adolescents with obesity [body mass index (BMI) >30 kg/m] were randomly assigned to "Living Low-Training Low" (LLTL, n = 19) group that slept in a normobaric normoxia condition and the LHTL (n = 16) group slept in a normobaric hypoxia room (14...
February 2018: Medicine (Baltimore)
M Lång, M B Skrifvars, J Siironen, P Tanskanen, M Ala-Peijari, T Koivisto, S Djafarzadeh, S Bendel
BACKGROUND: Normobaric hyperoxia is used to alleviate secondary brain ischaemia in patients with traumatic brain injury (TBI), but clinical evidence is limited and hyperoxia may cause adverse events. METHODS: An open label, randomised controlled pilot study comparing blood concentrations of reactive oxygen species (ROS), interleukin 6 (IL-6) and neuron-specific enolase (NSE) between two different fractions of inspired oxygen in severe TBI patients on mechanical ventilation...
February 20, 2018: Acta Anaesthesiologica Scandinavica
Derek M Culnan, Beretta Craft-Coffman, Genevieve H Bitz, Karel D Capek, Yiji Tu, William C Lineaweaver, Maggie J Kuhlmann-Capek
Carbon monoxide (CO) is a small molecule poison released as a product of incomplete combustion. Carbon monoxide binds hemoglobin, reducing oxygen delivery. This effect is exacerbated in the burned pregnant patient by fetal hemoglobin that binds CO 2.5- to 3-fold stronger than maternal hemoglobin. With no signature clinical symptom, diagnosis depends on patient injury history, elevated carboxyhemoglobin levels, and alterations in mental status. The standard of care for treatment of CO intoxication is 100% normobaric oxygen, which decreases the half-life of CO in the bloodstream from 5 hours to 1 hour...
March 2018: Annals of Plastic Surgery
Hannah G Caldwell, Geoff B Coombs, Michael M Tymko, Daniela Nowak-Flück, Philip N Ainslie
With exposure to acute normobaric hypoxia, global cerebral oxygen delivery is maintained via increases in cerebral blood flow (CBF); therefore, regional and localized changes in oxygen tension may explain neurocognitive impairment. Neurovascular coupling (NVC) is the close temporal and regional relationship of CBF to changes in neural activity and may aid in explaining the localized CBF response with cognitive activation. High-altitude related cognitive impairment is likely affected by hypocapnic cerebral vasoconstriction that may influence regional CBF regulation independent of hypoxia...
February 16, 2018: Physiology & Behavior
Stefan De Smet, Gommaar D'Hulst, Chiel Poffé, Ruud Van Thienen, Emanuele Berardi, Peter Hespel
PURPOSE: The myocellular response to hypoxia is primarily regulated by hypoxia-inducible factors (HIFs). HIFs thus conceivably are implicated in muscular adaptation to altitude training. Therefore, we investigated the effect of hypoxic versus normoxic training during a period of prolonged hypoxia ('living high') on muscle HIF activation during acute ischaemia. METHODS: Ten young male volunteers lived in normobaric hypoxia for 5 weeks (5 days per week, ~ 15.5 h per day, FiO2: 16...
February 8, 2018: European Journal of Applied Physiology
Stephan van der Zwaard, Franck Brocherie, Bengt L G Kom, Grégoire P Millet, Louise Deldicque, Willem J van der Laarse, Olivier Girard, Richard T Jaspers
In this study, we investigate adaptations in muscle oxidative capacity, fiber size and oxygen supply capacity in team-sport athletes after six repeated-sprint sessions in normobaric hypoxia or normoxia combined with 14 days of chronic normobaric hypoxic exposure. Lowland elite field hockey players resided at simulated altitude ({greater than or equal to}14 h∙d-1 at 2800-3000 m) and performed regular training plus six repeated-sprint sessions in normobaric hypoxia (3000 m; LHTLH; n=6) or normoxia (0 m, LHTL; n=6) or lived at sea level with regular training only (LLTL; n=6)...
February 8, 2018: Journal of Applied Physiology
Qian Xu, Shuang-Bo Fan, Yu-Lin Wan, Xian-Lan Liu, Liang Wang
AIMS: Although Hyperbaric oxygen therapy (HyperBOT) attract our attention successfully these days, it is still full of controversy on the treatment of acute stroke. The aim of this study is to assess the potential long-term neurological consequences and safety of using HyperBOT on intracerebral hemorrhage (ICH) in the diabetics. METHODS: In this prospective, randomized controlled trial, 79 diabetes patients suffering from acute ICH were randomized to treat for 60 minutes in a monoplace hyperbaric chamber pressurized with pure oxygen to 2...
February 3, 2018: Diabetes Research and Clinical Practice
Illya M Podolsky, Sergiy Yu Shtrygol', Vadym O Zubkov
The article presents the study of psycho- and neurotropic properties of novel 3-(N-R,R'-aminomethyl)-2-methyl-1H-quinolin-4-ones in vivo. The research was carried out using the open field test, elevated plus maze, rotarod test, tail suspension test, passive avoidance test after scopolamine-induced amnesia and acute normobaric hypoxia with hypercapnia. As a result, two promising substances have been found. According to our results 3-[[(4-methoxyphenyl)amino]methyl]-2-methyl-1H-quinolin-4-one in the dose of 10 mg/kg shows a specific sedative effect and a considerable anti-amnesic activity...
January 2018: Saudi Pharmaceutical Journal: SPJ: the Official Publication of the Saudi Pharmaceutical Society
C Strewe, R Zeller, M Feuerecker, M Hoerl, S Matzel, I Kumprej, A Crispin, B Johannes, T Debevec, I B Mekjavic, O Eiken, M Thiel, G Schelling, A Choukèr
Adenosine plays a role in the energy supply of cells and provokes differential, hormone-like functions in circulating cells and various tissues. Its release is importantly regulated by oxygen tension. This renders adenosine and its kinetics interesting to investigate in humans subjected to low oxygen conditions. Especially for space exploration scenarios, hypoxic conditions - together with reduced gravity - represent two foreseen living conditions when planning manned long-duration space missions or planetary habitats...
January 29, 2018: Scientific Reports
Miguel Aguilar, Alejandro González-Candia, Jorge Rodríguez, Catalina Carrasco-Pozo, Daniel Cañas, Claudio García-Herrera, Emilio A Herrera, Rodrigo L Castillo
More than 140 million people live and works (in a chronic or intermittent form) above 2500 m worldwide and 35 million live in the Andean Mountains. Furthermore, in Chile, it is estimated that 55,000 persons work in high altitude shifts, where stays at lowlands and interspersed with working stays at highlands. Acute exposure to high altitude has been shown to induce oxidative stress in healthy human lowlanders, due to an increase in free radical formation and a decrease in antioxidant capacity. However, in animal models, intermittent hypoxia (IH) induce preconditioning, like responses and cardioprotection...
January 26, 2018: International Journal of Molecular Sciences
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