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David Rizo-Roca, Jèssica B Bonet, Büsra Ínal, Juan Gabriel Ríos-Kristjánsson, Teresa Pagès, Ginés Viscor, Joan R Torrella
Altitude training has become increasingly popular in recent decades. Its central and peripheral effects are well-described; however, few studies have analyzed the effects of intermittent hypobaric hypoxia (IHH) alone on skeletal muscle morphofunctionality. Here, we studied the effects of IHH on different myofiber morphofunctional parameters, investigating whether contractile activity is required to elicit hypoxia-induced adaptations in trained rats. Eighteen male Sprague-Dawley rats were trained 1 month and then divided into three groups: (1) rats in normobaria (trained normobaric inactive, TNI); (2) rats subjected daily to a 4-h exposure to hypobaric hypoxia equivalent to 4,000 m (trained hypobaric inactive, THI); and (3) rats subjected daily to a 4-h exposure to hypobaric hypoxia just before performing light exercise (trained hypobaric active, THA)...
2018: Frontiers in Physiology
Colin R Carriker, Paige Rombach, Brooke M Stevens, Roger A Vaughan, Ann L Gibson
PURPOSE: To investigate changes in oxidative stress, arterial oxygen saturation (SaO2), blood pressure (BP), and heart rate (HR) while exercising in hypobaric hypoxia following acute dietary nitrate supplementation. METHODS: Nine well-trained (60.8±7.8 ml/kg/min) males (29±7 years) visited the lab on 3 occasions, each separated by 1 week. Visit 1 included a maximal aerobic cycling test (VO2max) and 5 five-minute increasing intensity exercise bouts in a normobaric environment (1600m)...
May 18, 2018: Applied Physiology, Nutrition, and Metabolism, Physiologie Appliquée, Nutrition et Métabolisme
Shareen Kaur Jaijee, Marina Quinlan, Pawel Tokarczuk, Matthew Clemence, Luke S Howard, J Simon R Gibbs, Declan O'Regan
Background - Coupling of right ventricular (RV) contractility to afterload is maintained at rest in the early stages of pulmonary arterial hypertension (PAH), but exercise may unmask depleted contractile reserves. We assessed whether elevated afterload reduces RV contractile reserve despite compensated resting function using non-invasive exercise imaging. Methods and Results - Fourteen patients with PAH (mean age 39.1 years, 10 females) and 34 healthy control subjects (mean age 35.6 years, 17 females) completed real-time cardiac magnetic resonance imaging during sub-maximal exercise breathing room-air...
May 18, 2018: American Journal of Physiology. Heart and Circulatory Physiology
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
Sei Won Kim, In Kyoung Kim, Jick Hwan Ha, Chang Dong Yeo, Hyeon Hui Kang, Jin Woo Kim, Sang Haak Lee
Hypoxia is a critical characteristic of solid tumors with respect to cancer cell survival, angiogenesis, and metastasis. Hyperoxic treatment has been attempted to reverse hypoxia by enhancing the amount of dissolved oxygen in the plasma. In this study, we evaluated the effects of normobaric hyperoxia on the progression of lung cancer to determine whether oxygen toxicity can be used in cancer therapy. Following a tail vein injection of the Lewis lung carcinoma cells, C57BL/6J mice were exposed to a 24-h normobaric hyperoxia/normoxia cycle for two weeks...
May 2018: Experimental Biology and Medicine
C J Boos, C M Lamb, M Midwinter, A Mellor, D R Woods, M Howley, T Stansfield, M Foster, J P O'hara
The binding of high-mobility group box-1 (HMGB-1) to the membrane receptor for advanced glycation end-products (mRAGE) is a key early mediator of non-infectious inflammation and its triggers include ischaemia/hypoxia. The effects of acute hypoxia on soluble RAGE (sRAGE) are unknown. Fourteen healthy adults (50% women; 26.6+/-3.8 years) were assessed at baseline normoxia (T0), followed by four time-points (T90, 95, 100 and 180 minutes) over three hours of continuous normobaric hypoxia (NH, 4450m equivalent) and again 60 minutes after return to normoxia (T240)...
May 10, 2018: Physiological Research
Jing Lan, Elga Esposito, Cenk Ayata, Aneesh B Singhal, Eng H Lo, Xunming Ji
BACKGROUND AND PURPOSE: The efficacy of neuroprotective approaches in stroke may be influenced by existing comorbidities. Here, we compared the effects of normobaric hyperoxia (NBO) in normotensive versus hypertensive rats subjected to transient focal cerebral ischemia. METHODS: Male Sprague-Dawley and spontaneously hypertensive rats were subjected to transient focal ischemia via intraluminal filament occlusions of the middle cerebral artery. NBO was started 15 minutes after ischemic onset and stopped at the time of reperfusion...
April 30, 2018: Stroke; a Journal of Cerebral Circulation
Bin Peng, Shun-Hua Peng, Run-Ming Qu, Li-Hua Xu, Zheng-Lin Jiang
Human beings are exposed to compressed air or a nitrogen-oxygen mixture, they will produce signs and symptoms of nitrogen narcosis such as amnesia or even loss of memory, which may be disappeared once back to the normobaric environment. This study was designed to investigate the effect of nitrogen narcosis induced by repetitive hyperbaric nitrogen-oxygen mixture exposure on long-term cognitive function in newborn mice and the underlying mechanisms. The electroencephalogram frequency was decreased while the amplitude was increased in a pressure-dependent manner during 0...
2018: PloS One
Junming Fan, Hui Guang, Haizeng Zhang, Danyang Chen, Lu Ding, Xiaofang Fan, Feng Xue, Zhuohui Gan, Yongyu Wang, Sunzhong Mao, Lianggang Hu, Yongsheng Gong
We previously showed that apelin-13 ameliorates chronic normobaric hypoxia (CNH)-induced anxiety-like behavior in mice, the mechanism, however, is not well known. This study aims to investigate whether SIRT1 is involved in the anxiolytic effect of apelin-13 in CNH-treated mice, and to illustrate the potential underlying mechanism. We showed that apelin-13 treatment reversed a decrease of SIRT1 and an increase of acetylated p65 (lysine 310) proteins expression in hippocampus of CNH-treated mice, indicating that apelin-13 inhibited NF-κB signaling pathway by activating SIRT1...
April 19, 2018: Neuroscience
Iveta Nedvedova, David Kolar, Barbara Elsnicova, Daniela Hornikova, Jiri Novotny, Martin Kalous, Michal Pravenec, Jan Neckar, Frantisek Kolar, Jitka M Zurmanova
Recently we have shown that adaptation to continuous normobaric hypoxia (CNH) decreases myocardial ischemia/reperfusion injury in spontaneously hypertensive rats (SHR) and in conplastic strain (SHR-mtBN ). The protective effect was stronger in the latter group characterized by a selective replacement of SHR mitochondrial genome with that of a more ischemia-resistant Brown Norway strain. The aim of the present study was to examine the possible involvement of the hypoxia inducible factor (HIF)-dependent pathway of the protein kinase B/glucose transporters/hexokinase (Akt/GLUT/HK) in this mitochondrial genome-related difference of the cardioprotective phenotype...
April 20, 2018: Physiological Genomics
Jean-Claude Baron
After ischaemic stroke, brain damage can be curtailed by rescuing the 'ischaemic penumbra' - that is, the severely hypoperfused, at-risk but not yet infarcted tissue. Current evidence-based treatments involve restoration of blood flow so as to salvage the penumbra before it evolves into irreversibly damaged tissue, termed the 'core'. Intravenous thrombolysis (IVT) can salvage the penumbra if given within 4.5 h after stroke onset; however, the early recanalization rate is only ~30%. Direct removal of the occluding clot by mechanical thrombectomy considerably improves outcomes over IVT alone, but despite early recanalization in > 80% of cases, ~50% of patients who receive this treatment do not enjoy functional independence, usually because the core is already too large at the time of recanalization...
April 19, 2018: Nature Reviews. Neurology
Nektarios A M Stavrou, Tadej Debevec, Ola Eiken, Igor B Mekjavic
Previous research, although limited, suggests that both hypoxia and bed rest influence psychological responses by exaggerating negative psychological responses and attenuating positive emotions. The present study investigated the effect of a 21-day prolonged exposure to normobaric hypoxia and bed rest on affective responses and fatigue. Eleven healthy participants underwent three 21-day interventions using a cross-over design: (1) normobaric hypoxic ambulatory confinement (HAMB), (2) normobaric hypoxic bed rest (HBR) and (3) normoxic bed rest (NBR)...
2018: Frontiers in Psychology
Z Deng, W Chen, J Jin, J Zhao, H Xu
This study reviews the oxygen therapy (normobaric oxygen [NBO] and hyperbaric oxygen [HBO]) in both stroke and traumatic brain injury (TBI) patients and meta-analyzes the efficacy of two oxygen therapies in different kinds of injuries. In stroke patients, NBO showed significant improvement in reperfusion rate while there is no favorable outcome effect of HBO treatment. In patients with TBI, HBO showed significant improvement of Glasgow outcome scale score and reduction of overall mortality while NBO may play a favorable role in improving brain metabolism...
April 2018: Nigerian Journal of Clinical Practice
Jiayue Ding, Da Zhou, Meng Sui, Ran Meng, Ankush Chandra, Jie Han, Yuchuan Ding, Xunming Ji
Background Normobaric oxygen (NBO) has received considerable attention due to controversial data in brain protection in patients with acute stroke. This study aims to analyze current data of NBO on brain protection as used in the clinic. Methods We searched for and reviewed relevant articles and references from Pubmed, Medline, Embase, Cochrane, and that were published prior to October 2017. Data from prospective studies were processed using RevMan5.0 software, provided by Cochrane collaboration and transformed using relevant formulas...
March 30, 2018: Neurological Research
V N Kotel'nikov, I O Osipov, Yu V Zayats, B I Gel'tser
The effects of exogenous normobaric hypoxic hypoxia on vegetative control of the heart and BP were examined in Wistar rats. The reference ranges of variation pulsometry parameters were determined in rats with normoxemia for 3 physiological variants of autonomic homeostasis: eutony, sympathicotony, and vagotony. Most rats (80%) demonstrated autonomic eutony. The study showed that saturation of arterial blood with oxygen is the most adequate assessment of severity of acute exogenous normobaric hypoxic hypoxia progressing within a closed hypoxic chamber, which standardizes this method and minimizes inaccuracies resulting from individual sensitivity to hypoxic stress...
March 26, 2018: Bulletin of Experimental Biology and Medicine
Aitor Fernández Menéndez, Gilles Saudan, Ludovic Sperisen, Didier Hans, Mathieu Saubade, Grégoire P Millet, Davide Malatesta
OBJECTIVE: The aim of this study was to compare the effects of short-term hypoxic versus normoxic training at preferred walking speed (PWS) on energetics, mechanics, efficiency, and metabolic risk markers in individuals with obesity. METHODS: Twenty-three subjects with obesity performed nine 1-hour sessions at PWS under hypoxia (3,000 m, n = 12; BMI: 34.0 ± 0.8 kg/m2 ) or normoxia (360 m, n = 11; BMI: 32.9 ± 0.8 kg/m2 ). Participants performed six 5-minute walking trials at different speeds (PWS, 0...
March 25, 2018: Obesity
Romain Goulay, Antoine Drieu, Camille Di Palma, Palma Pro-Sistiaga, Nicolas Delcroix, Laurent Chazalviel, Romaric Saulnier, Clément Gakuba, Suzanne Goursaud, Allan R Young, Maxime Gauberti, Cyrille Orset, Evelyne Emery, Denis Vivien, Thomas Gaberel
It was previously reported that normobaric oxygen therapy (NBO) significantly affected T2∗ -weighted imaging in a mouse model of intracerebral hemorrhage (ICH). However, it is unclear whether a similar phenomenon exists in large volume ICH as seen in human pathology. We investigated the effects of NBO on T2∗ -weighted images in a pig model of ICH. Our data show that NBO makes disappear a peripheral crown of the hematoma, which in turn decreases the apparent volume of ICH by 18%. We hypothesized that this result could be translated to ICH in human, and subsequently could lead to inaccurate diagnostic...
March 20, 2018: Journal of Clinical Neuroscience: Official Journal of the Neurosurgical Society of Australasia
Frank K Butler, Catherine Hagan, Karen Van Hoesen, Heather Murphy-Lavoie
Objective: This case report presents a patient with central retinal artery occlusion (CRAO) who was successfully treated with hyperbaric oxygen (HBO₂) but subsequently suffered a recurrence of his visual loss. Methods: CRAO may be treated successfully with HBO₂ if treatment is undertaken promptly after the onset of vision loss. The goal of HBO₂ therapy is to oxygenate the ischemic inner retinal layers via diffusion from the hyperoxygenated choroidal circulation until recanalization of the central retinal artery occurs...
January 2018: Undersea & Hyperbaric Medicine: Journal of the Undersea and Hyperbaric Medical Society, Inc
Min-Young Kwon, Narae Hwang, Young-Jun Park, Mark A Perrella, Su Wol Chung
Expression of nucleotide-binding oligomerization domain protein 2 (NOD2) is upregulated in pulmonary artery smooth muscle cells (PASMCs) during hypoxia. To investigate the involvement of NOD2 in the pulmonary vascular response to hypoxia, we subjected wild-type and NOD2-deficient mice to chronic normobaric hypoxic conditions. Compared to wild-type mice, NOD2-deficient mice developed severe pulmonary hypertension with exaggerated elevation of right ventricular systolic pressure, profound right ventricular hypertrophy and striking vascular remodeling after exposure to hypoxia...
February 27, 2018: Oncotarget
Benedikt Treml, Axel Kleinsasser, Karl-Heinz Stadlbauer, Iris Steiner, Werner Pajk, Michael Pilch, Martin Burtscher, Hans Knotzer
As is known, hypoxia leads to an increase in microcirculatory blood flow of the skin in healthy volunteers. In this pilot study, we investigated microcirculatory blood flow and reactive hyperemia of the skin in healthy subjects in normobaric hypoxia. Furthermore, we examined differences in microcirculation between hypoxic subjects with and without short-term acclimatization, whether or not skin microvasculature can acclimatize. Fourty-six healthy persons were randomly allocated to either short-term acclimatization using intermittent hypoxia for 1 h over 7 days at an FiO2 0...
2018: Frontiers in Physiology
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