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acute intermittent hypoxia

Ken D O'Halloran, Philip Lewis, Fiona McDonald
Obstructive sleep apnoea syndrome (OSAS) is a devastating respiratory control disorder more common in men than women. The reasons for the sex difference in prevalence are multifactorial, but are partly attributable to protective effects of oestrogen. Indeed, OSAS prevalence increases in post-menopausal women. OSAS is characterized by repeated occlusions of the pharyngeal airway during sleep. Dysfunction of the upper airway muscles controlling airway calibre and collapsibility is implicated in the pathophysiology of OSAS, and sex differences in the neuro-mechanical control of upper airway patency are described...
November 21, 2016: Respiratory Physiology & Neurobiology
Emilia Sforza, Fréderic Roche
Obstructive sleep apnea (OSA) is a prevalent sleep disorder considered as an independent risk factor for cardiovascular consequences, such as systemic arterial hypertension, ischemic heart disease, cardiac arrhythmias, metabolic disorders, and cognitive dysfunction. The pathogenesis of OSA-related consequence is assumed to be chronic intermittent hypoxia (IH) inducing alterations at the molecular level, oxidative stress, persistent systemic inflammation, oxygen sensor activation, and increase of sympathetic activity...
2016: Hypoxia
Kyung Soo Kim, Jin Wook Kwak, Su Jin Lim, Yong Kyun Park, Hoon Shik Yang, Hyun Jik Kim
The main mechanism of pathogenesis which causes systemic complications in obstructive sleep apnea (OSA) patients is believed to be intermittent hypoxia-induced intermediary effect and it depends on the burden of oxidative stress during sleep. We aimed to search the predictive markers which reflect the burden of systemic oxidative stress in patients with OSA and whether excessive telomere length shortening is a characteristic feature that can assess oxidative stress levels. We used quantitative PCR to measure telomere length using peripheral blood genomic DNA...
October 2016: Aging and Disease
Petra Micova, Klara Hahnova, Marketa Hlavackova, Barbara Elsnicova, Anna Chytilova, Kristyna Holzerova, Jitka Zurmanova, Jan Neckar, Frantisek Kolar, Olga Novakova, Jiri Novotny
Cardiac resistance against acute ischemia/reperfusion (I/R) injury can be enhanced by adaptation to chronic intermittent hypoxia (CIH), but the changes at the molecular level associated with this adaptation are still not fully explored. Phospholipase A2 (PLA2) plays an important role in phospholipid metabolism and may contribute to membrane destruction under conditions of energy deprivation during I/R. The aim of this study was to determine the effect of CIH (7000 m, 8 h/day, 5 weeks) on the expression of cytosolic PLA2α (cPLA2α) and its phosphorylated form (p-cPLA2α), as well as other related signaling proteins in the left ventricular myocardium of adult male Wistar rats...
September 30, 2016: Molecular and Cellular Biochemistry
Eduardo V Lemes, Eduardo Colombari, Daniel B Zoccal
Abdominal expiratory activity is absent at rest and is evoked during metabolic challenges, such as hypercapnia and hypoxia, or after the exposure to intermittent hypoxia (IH). The mechanisms engaged during this process are not completely understood. In this study, we hypothesized that serotonin (5-HT), acting in the retrotrapezoid nucleus/parafacial respiratory group (RTN/pFRG), is able to generate active expiration. In anesthetized (urethane, i.p.), tracheostomized, spontaneously-breathing adult male Holtzman rats we microinjected a serotoninergic agonist and antagonist bilaterally in the RTN/pFRG and recorded diaphragm and abdominal muscle activities...
September 22, 2016: Journal of Applied Physiology
Jag Sunderram, John Semmlow, Pranav Patel, Harshit Rao, Glen Chun, Priya Agarwala, Mantu Bhaumik, Oanh Le-Hoang, Shou-En Lu, Judith A Neubauer
Chronic intermittent hypoxia (CIH) increases sympathetic tone, and respiratory instability. Our previous work showed that chronic hypoxia induces the oxygen sensing enzyme, heme oxygenase-1 (HO-1) within the C1 sympathoexcitatory region and the pre-Bötzinger complex (pre-BötC). We therefore examined the effect of CIH on time course of induced expression of HO-1 within these regions and determined whether the induction of HO-1 correlated with changes in respiratory, sigh frequency, and sympathetic responses (spectral analysis of heart rate) to acute hypoxia (10%O2) during 10 days of exposure to CIH in chronically instrumented awake wild type (WT) and HO-1 null mice (HO-1(-/-))...
September 8, 2016: Journal of Applied Physiology
Barbara J Morgan, Melissa L Bates, Rodrigo Del Rio, Zunyi Wang, John M Dopp
Chronic exposure to intermittent hypoxia (CIH) elicits plasticity of the carotid sinus and phrenic nerves via reactive oxygen species (ROS). To determine whether CIH-induced alterations in ventilation, metabolism, and heart rate are also dependent on ROS, we measured responses to acute hypoxia in conscious rats after 14 and 21 d of either CIH or normoxia (NORM), with or without concomitant administration of allopurinol (xanthine oxidase inhibitor), combined allopurinol plus losartan (angiotensin II type 1 receptor antagonist), or apocynin (NADPH oxidase inhibitor)...
December 2016: Respiratory Physiology & Neurobiology
Micah A Skeens, Jennifer McArthur, Ira M Cheifetz, Christine Duncan, Adrienne G Randolph, Joseph Stanek, Leslie Lehman, Rajinder Bajwa
Veno-occlusive disease (VOD) is a potentially fatal complication of hematopoietic stem cell transplantation (HSCT). Patients with VOD are often critically ill and require close collaboration between transplant physicians and intensivists. We surveyed members of a consortium of pediatric intensive care unit (PICU) and transplant physicians to assess variability in the self-reported approach to the diagnosis and management of VOD. An internet-based self-administered survey was sent to pediatric HSCT and PICU providers from September 2014 to February 2015...
October 2016: Biology of Blood and Marrow Transplantation
Michael J Devinney, Nicole L Nichols, Gordon S Mitchell
UNLABELLED: Acute intermittent hypoxia (AIH) induces phrenic long-term facilitation (pLTF), a form of spinal motor plasticity. Competing mechanisms give rise to phrenic motor facilitation (pMF; a general term including pLTF) depending on the severity of hypoxia within episodes. In contrast, moderate acute sustained hypoxia (mASH) does not elicit pMF. By varying the severity of ASH and targeting competing mechanisms of pMF, we sought to illustrate why moderate AIH (mAIH) elicits pMF but mASH does not...
July 27, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Bimit Mahat, Étienne Chassé, Jean-François Mauger, Pascal Imbeault
BACKGROUND: Adipose tissue regulates postprandial lipid metabolism by storing dietary fat through lipoprotein lipase-mediated hydrolysis of exogenous triglycerides, and by inhibiting delivery of endogenous non-esterified fatty acid to nonadipose tissues. Animal studies show that acute hypoxia, a model of obstructive sleep apnea, reduces adipose tissue lipoprotein lipase activity and increases non-esterified fatty acid release, adversely affecting postprandial lipemia. These observations remain to be tested in humans...
2016: Journal of Translational Medicine
Seung Jae Kim, Paul M Pilowsky, Melissa M J Farnham
Intermittent hypoxia causes a persistent increase in sympathetic nerve activity (SNA), which progresses to hypertension in conditions such as obstructive sleep apnea. Orexins (A and B) are hypothalamic neurotransmitters with arousal-promoting and sympathoexcitatory effects. We investigated whether the sustained elevation of SNA, termed sympathetic long-term facilitation, after acute intermittent hypoxia (AIH) is caused by endogenous orexin acting on spinal sympathetic preganglionic neurons. The role of orexin in the increased SNA response to AIH was investigated in urethane-anesthetized, vagotomized, and artificially ventilated Sprague-Dawley rats (n = 58)...
September 2016: Journal of Pharmacology and Experimental Therapeutics
Mathhew E Pamenter, Frank L Powell
Ventilatory responses to hypoxia vary widely depending on the pattern and length of hypoxic exposure. Acute, prolonged, or intermittent hypoxic episodes can increase or decrease breathing for seconds to years, both during the hypoxic stimulus, and also after its removal. These myriad effects are the result of a complicated web of molecular interactions that underlie plasticity in the respiratory control reflex circuits and ultimately control the physiology of breathing in hypoxia. Since the time domains of the physiological hypoxic ventilatory response (HVR) were identified, considerable research effort has gone toward elucidating the underlying molecular mechanisms that mediate these varied responses...
2016: Comprehensive Physiology
Jean-Paul Richalet
The adrenergic system is part of a full array of mechanisms allowing the human body to adapt to the hypoxic environment. Triggered by the stimulation of peripheral chemoreceptors, the adrenergic centers in the medulla are activated in acute hypoxia and augment the adrenergic drive to the organs, especially to the heart, leading to tachycardia. With prolonged exposure to altitude hypoxia, the adrenergic drive persists, as witnessed by elevated blood concentrations of catecholamines and nerve activity in adrenergic fibers...
2016: Advances in Experimental Medicine and Biology
R W A Mackenzie, P Watt
Although the mechanisms are largely unidentified, the chronic or intermittent hypoxic patterns occurring with respiratory diseases, such as chronic pulmonary disease or obstructive sleep apnea (OSA) and obesity, are commonly associated with glucose intolerance. Indeed, hypoxia has been widely implicated in the development of insulin resistance either via the direct action on insulin receptor substrate (IRS) and protein kinase B (PKB/Akt) or indirectly through adipose tissue expansion and systemic inflammation...
2016: Journal of Diabetes Research
Jun-Jun Kang, Wei-Hua Liang, Chun-Sing Lam, Xiao-Feng Huang, Shou-Jing Yang, Margaret T T Wong-Riley, Man-Lung Fung, Ying-Ying Liu
The rostral ventrolateral medulla (RVLM) contains cardiovascular-related catecholaminergic neurons and respiratory-related pre-Bötzinger complex (pre-BötC) neurons, which are intermingled and functionally connected for coordinating cardiorespiratory activities. Daily acute intermittent hypoxia (dAIH) is known to elicit respiratory plasticity. However, it is unclear if the catecholaminergic neurons directly synapse onto pre-BötC neurons, and if the local circuitry exhibits plasticity when exposed to dAIH...
May 27, 2016: Experimental Neurology
Valerii B Shatylo, Tatiana V Serebrovska, Anna V Gavalko, Egor Egorov, Oleg V Korkushko
Shatylo, Valerii B., Tetiana V. Serebrovska, Anna V. Gavalko, Egor Egorov, and Oleg V. Korkushko. Acute hypoxic test in patients with prediabetes. High Alt Med Biol. 17:101-107, 2016.-Prediabetes is a state of impaired carbohydrate metabolism when not all of the symptoms required to label a person as diabetic are present, but blood glucose is higher than in healthy subjects. Recent evidence suggests that intermittent hypoxia training (IHT) might provide a cost-effective strategy for improving metabolic functioning...
June 2016: High Altitude Medicine & Biology
Julie Deguil, Laura Ravasi, Laura Lanteaume, Yves Lamberty, Regis Bordet
Empirical evidence currently supports the idea that neurovascular dysfunction is involved in the neurodegenerative process of Alzheimer's disease (AD). In fact, epidemiological studies report that i) vascular risk factors are directly associated with an increased incidence of AD and ii) vascular lesions are frequently co-existent with AD. The neurovascular unit is a key control system for oxygen and nutrients exchange between neurons and microvessels so the integrity of this system is essential for neuronal activity and cell survival...
2016: CNS & Neurological Disorders Drug Targets
Erica A Dale, Daryl P Fields, Michael J Devinney, Gordon S Mitchell
Phrenic long-term facilitation (pLTF) is a form of hypoxia-induced spinal respiratory motor plasticity that requires new synthesis of brain derived neurotrophic factor (BDNF) and activation of its high-affinity receptor, tropomyosin receptor kinase B (TrkB). Since the cellular location of relevant TrkB receptors is not known, we utilized intrapleural siRNA injections to selectively knock down TrkB receptor protein within phrenic motor neurons. TrkB receptors within phrenic motor neurons are necessary for BDNF-dependent acute intermittent hypoxia-induced pLTF, demonstrating that phrenic motor neurons are a critical site of respiratory motor plasticity...
May 13, 2016: Experimental Neurology
Vahid Mohsenin
PURPOSE: The aim of this review is to discuss hypoxia-induced pulmonary hypertension (PH) and the role of microRNAs (miRNAs). BACKGROUND: Acute global hypoxia causes pulmonary vasoconstriction and increased pulmonary arterial blood pressure. Chronic exposure to sustained or intermittent hypoxia as in high altitude residents, chronic obstructive lung disease and sleep-disordered breathing can lead to pulmonary hypertension (PH) and right ventricular dysfunction. The development of PH is a poor prognostic sign in these patients that affects both quality of life and mortality...
September 2016: Sleep & Breathing, Schlaf & Atmung
A Navarrete-Opazo, B J Dougherty, G S Mitchell
Daily acute intermittent hypoxia (dAIH) improves breathing capacity after C2 spinal hemisection (C2HS) in rats. Since C2HS disrupts spinal serotonergic innervation below the injury, adenosine-dependent mechanisms underlie dAIH-induced functional recovery 2weeks post-injury. We hypothesized that dAIH-induced functional recovery converts from an adenosine-dependent to a serotonin-dependent, adenosine-constrained mechanism with chronic injury. Eight weeks post-C2HS, rats began dAIH (10, 5-min episodes, 10.5% O2; 5-min intervals; 7days) followed by AIH 3× per week (3×wAIH) for 8 additional weeks with/without systemic A2A receptor inhibition (KW6002) on each AIH exposure day...
April 11, 2016: Experimental Neurology
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