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Results 451 - 500 of 1559
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Appenzeller Otto - - 2006
BACKGROUND AND PURPOSE: Andean highlanders, unlike Ethiopians, develop chronic mountain sickness (CMS), a maladaptation to their native land. Ambient hypoxia induces NO-mediated vasodilatation. Fitness for life at altitude might be revealed by cerebrovascular responses to NO. METHODS: Nine altitude-native men were examined at 3622 and 794 m in Ethiopia and ...
Evans A Mark - - 2006
In order to maintain tissue partial pressure of oxygen (P(O(2))) within physiological limits, vital homeostatic mechanisms monitor O(2) supply and respond to a fall in P(O(2)) by altering respiratory and circulatory function, and the capacity of the blood to transport O(2). Two systems that are key to this process in ...
Sandblom Erik - - 2006
Central venous blood pressure (P(ven)) increases in response to hypoxia in rainbow trout (Oncorhynchus mykiss), but details on the control mechanisms of the venous vasculature during hypoxia have not been studied in fish. Basic cardiovascular variables including P(ven), dorsal aortic blood pressure, cardiac output, and heart rate were monitored in ...
Inamoto Sakiko - - 2006
Hypoxia caused by sleep apnea might be associated with an increased risk of cardiovascular events in subjects with metabolic syndrome. The aim of this study was to examine the effect of hypoxia on the left ventricular (LV) myocardium and evaluate the cardioprotective effect of an angiotensin-II receptor blocker (ARB) in ...
Kamin Wolfgang - - 2006
BACKGROUND: For patients with cystic fibrosis (CF)-related partial respiratory insufficiency and reduced arterial oxygen tension at ground level, the mild hypobaric environment on commercial jet aircraft poses the risk of severe hypoxemia. Thus, physicians should be able to estimate the extent of in-flight hypoxia. OBJECTIVES: To derive tools for estimating ...
Toff William D WD Department of Cardiovascular Sciences, University of Leicester, Glenfield Hospital, Leicester, England. - - 2006
The link between long-haul air travel and venous thromboembolism is the subject of continuing debate. It remains unclear whether the reduced cabin pressure and oxygen tension in the airplane cabin create an increased risk compared with seated immobility at ground level. To determine whether hypobaric hypoxia, which may be encountered ...
Harper S L - - 2006
Hypoxic exposure experienced during sensitive developmental periods can shape adult physiological capabilities and define regulatory limits. Tadpole shrimp were reared under normoxic (19-21 kPa O(2)), moderate (10-13 kPa O(2)) or severe (1-3 kPa O(2)) hypoxic conditions to investigate the influence of developmental oxygen partial pressure (P(O(2))) on adult metabolic, respiratory ...
Najem Boutaïna - - 2006
Sympathetic overactivity is implicated in the increased cardiovascular risk of cigarette smokers. Excitatory nicotinic receptors are present on peripheral chemoreceptor cells. Chemoreceptors located in the carotid and aortic bodies increase ventilation (Ve), blood pressure (BP), heart rate (HR), and sympathetic nerve activity to muscle circulation (MSNA) in response to hypoxia. ...
Gilmartin Geoffrey - - 2006
Systemic hemodynamics, including forearm blood flow and ventilatory parameters, were evaluated in 21 subjects before and after exposure to 8 h of poikilocapnic hypoxia. To evaluate the role of sympathetic nervous system activation in the changes, in 10 of these subjects, we measured muscle sympathetic nerve activity (MSNA) before and ...
Marik Paul E - - 2006
With improvement in supportive care patients rarely die from their presenting illness but rather from its sequela, namely sequential multi-organ failure. Tissue hypoxia is believed to be the causation of multi-organ dysfunction syndrome (MODS). The expedient detection and correction of tissue hypoxia may therefore limit the development of MODS. The ...
Bianciardi Paola - - 2006
We studied the in vivo persistence of hypoxia-inducible factor-1alpha (HIF-1alpha), main transducer of hypoxia, the differential response in organs exposed to the same degree of hypoxemia and the relationship with apoptosis. We measured HIF-1alpha (immunohistochemistry peroxidase and Western blot) and apoptosis (TUNEL) in heart, liver, kidney, gastrocnemius, and brain of ...
Stecyk J A W - - 2006
Little is known of the cardiorespiratory control mechanisms utilized by hypoxia-tolerant teleost fish to tolerate prolonged periods (h) of near anoxic exposure. Here, we report on the cardiorespiratory control mechanisms of the common carp Cyprinus carpio L. during normoxia and prolonged, severe hypoxic (<0.3 mg O(2) L(-1)) exposure at acclimation ...
Sun Tzong-Bor - - 2006
OBJECTIVES: Long-term hypoxia results in hemodynamic breakdown in patients in the intensive care unit; however, intermittent hypoxia causes hypertension in individuals with sleep apnea. The objective of this study was to explore the sequential cardiovascular neural alterations in response to acute hypoxic apnea. DESIGN: The authors conducted a prospective, randomized ...
Dehler M - - 2006
Alveolar hypoxia causes pulmonary oedema associated with increased lung capillary pressure and decreased alveolar fluid reabsorption. However, the role of altered permeability is unclear. The aim of the present study was to test whether hypoxia affects alveolar permeability and induces pulmonary oedema in rat lungs, and whether terbutaline affects oedema ...
Perry S F - - 2006
Experiments were conducted to test the hypothesis that branchial gas transfer is enhanced in rainbow trout during hypoxia or hypercarbia by bradycardia and systemic vasoconstriction. Gas transfer was indirectly assessed by continuous monitoring of arterial blood gases, PaO2 and PaCO2. Cardiac frequency was maximally decreased by 34.9+/-4.3 and 8.6+/-3.2 bpm ...
Peth Simon - - 2006
Increased pulmonary capillary pressure and inhibition of alveolar Na+ transport putatively contribute to the formation of pulmonary edema in alveolar hypoxia such as at high altitude. Since both events might be linked to the inhibition of K+ channels, we studied whether in vivo application of minoxidil, a stimulator of ATP-gated ...
Wu Tianyi - - 2006
Since the beginning of the Himalayan climbing era, the anecdotal extraordinary physical performance at high altitude of Sherpas and Tibetans has intrigued scientists interested in altitude adaptation. These ethnic groups may have been living at high altitude for longer than any other population, and the hypothesis of a possible evolutionary ...
Bailey Damian M - - 2006
The present study combined molecular and neuroimaging techniques to examine if free radical-mediated damage to barrier function in hypoxia would result in extracellular edema, raise intracranial pressure (ICP) and account for the neurological symptoms typical of high-altitude headache (HAH) also known as acute mountain sickness (AMS). Twenty-two subjects were randomly ...
Siqués Patricia - - 2006
The aim of this study was to evaluate the effects of two periods of intermittent exposure to hypoxia (428 torr) in rats over 12 months. The conditions of CIH4x4 (4 days in hypoxia, 4 days in normoxia, n = 50) and CIH2x2 (2 days in hypoxia, 2 days in normoxia, ...
Sica Anthony L - - 2006
Spectral analysis of the cardiac time series has been used as a tool for assessing levels of parasympathetic and sympathetic modulation of the sinoatrial node. In the present investigation we evaluated daily changes in heart rate variability spectra in conscious neonatal piglets that were either neurally intact (n = 5) ...
Majmudar Kuntal - - 2006
The effects of cobalt chloride on heart rate, blood pressure, ventilatory frequency and opercular pressure amplitude in channel catfish, Ictalurus punctatus were measured to evaluate the potential of cobalt as a histochemical probe to study mechanisms of oxygen chemoreception, as well as assess the general effects of cobalt on the ...
Sharma Sumeet K - - 2006
Oxygen tension is a critical factor for appropriate embryonic and fetal development. Chronic hypoxia exposure alters cardiovascular (CV) function and structure in the late fetus and newborn, yet the immature myocardium is considered to be less sensitive to hypoxia than the mature heart. We tested the hypothesis that hypoxia during ...
Iiyori Nao - - 2005
We have recently demonstrated that genetic background significantly impacts the blood pressure and heart rate response to hypoxia (Campen MJ, Tagaito Y, Li J, Balbir A, Tankersley CG, Smith P, Schwartz A, and O'Donnell CP. Physiol Genomics 20: 15-20, 2005). Because hypoxia is considered a mediator of the acute and ...
McMahon Timothy J - - 2005
The mechanism by which hypoxia [low partial pressure of O(2) (pO(2))] elicits signaling to regulate pulmonary arterial pressure is incompletely understood. We considered the possibility that, in addition to its effects on smooth muscle, hypoxia may influence pulmonary vascular tone through an effect on RBCs. We report that exposure of ...
Hinojosa-Laborde Carmen - - 2005
Intermittent hypoxia is used to mimic the arterial hypoxemia that occurs during sleep apnea. The present study examined the blood pressure and heart rate responses to exposure to intermittent hypoxia in male rats and in female rats before and after ovariectomy. Rats were instrumented with telemetry transmitters and blood pressure, ...
Iwamoto Tokuzen - - 2005
It is not yet clear whether there is an intermittent hypoxia (IHx) threshold to elicit polycythemia and blood pressure elevation, and whether blood hemoglobin concentration ([Hb]) increases with an increase in the hypoxic exposure period. We have previously shown that repetitive exposure to 10% O2 for 60 min/day for up ...
SokoĊ‚owska B - - 2005
In the present study we investigated whether classical or non-classical statistical methods might be useful in the diagnosis of early changes evoked by intermittent hypoxia (IH) in an experimental model. The experiments were carried out in anesthetized, spontaneously breathing rabbits. IH consisted of 5 cycles of breathing 14% O(2) in ...
Armstead William M - - 2005
BACKGROUND AND PURPOSE: Babies are frequently exposed to hypoxia and ischemia during the perinatal period as a result of stroke or problems with delivery or respiratory management post delivery. The only U.S. Food and Drug Administration-approved treatment for acute stroke is the administration of tPA. Nonetheless, basic science studies indicate ...
Merklinger Sandra L - - 2005
Transgenic mice overexpressing the calcium binding protein, S100A4/Mts1, occasionally develop severe pulmonary vascular obstructive disease. To understand what underlies this propensity, we compared the pulmonary vascular hemodynamic and structural features of S100A4/Mts1 with control C57Bl/6 mice at baseline, following a 2-week exposure to chronic hypoxia, and after 1 and 3 ...
Cooper V L - - 2005
Asphyxia, which occurs during obstructive sleep apnoeic events, alters the baroreceptor reflex and this may lead to hypertension. We have recently reported that breathing an asphyxic gas resets the baroreceptor-vascular resistance reflex towards higher pressures. The present study was designed to determine whether this effect was caused by the reduced ...
López-Ramos J C - - 2005
Nitrate, nitrite, and other nitroso compounds (NOxs) had been proposed as possible nitric oxide (NO) storage molecules. The present work examines, by means of chemiluminescence analysis, changes in NOx serum levels in rats 1 h before and 24, 48, and 72 h after exposure to acute hypobaric hypoxia (HH; barometric ...
Dutschmann Mathias - - 2005
The neural control of respiratory airflow via the vocal fold is characterized by inspiratory abduction and postinspiratory (early expiratory) adduction causing decreases and increases in glottal resistance, respectively. The postinspiratory increase in glottal resistance plays a major role in braking the speed of expiratory airflow, to act against the high ...
Balanos George M - - 2005
In healthy humans, changes in cardiac output are commonly accommodated with minimal change in pulmonary artery pressure. Conversely, exposure to hypoxia is associated with substantial increases in pulmonary artery pressure. In this study we used non-invasive measurement of an index of pulmonary artery pressure, the maximum systolic pressure difference across ...
Campen M J - - 2005
We investigated the effects of 1) acute hypoxia and 2) 5 wk of chronic intermittent hypoxia (IH) on the systemic and pulmonary circulations of C57BL/6J mice. Mice were chronically instrumented with either femoral artery or right ventricular catheters. In response to acute hypoxia (4 min of 10% O2; n = ...
Attard Jo-Anne P - - 2005
PURPOSE: Acute postoperative systemic hypoxia occurs frequently in the clinical setting following intestinal resection, as a result of complications such as pneumonia, pulmonary edema, or the acute respiratory distress syndrome. Although it is well established that oxygen is essential for metabolism in general and intestinal anastomotic healing, the mechanisms by ...
Jellyman J K - - 2005
OBJECTIVE: This study tested the hypothesis that pregnancy affects the cardiovascular responses to hypoxia by altering the outputs of the peripheral components of the stress system and independent of changes in P(a)CO(2). DESIGN: Comparison of cardiovascular and endocrine responses to acute isocapnic hypoxia between pregnant and non-pregnant ewes. SETTING: Experimental ...
Solis de los Santos F - - 2005
Modern broilers have been genetically selected for an increased growth rate and improved feed conversion, but they are also more susceptible to ascites. Ascites occurs when there is an imbalance between available oxygen and the oxygen demand of the broiler. We hypothesized that promoting neonatal gut development with a prebiotic, ...
Foster Glen E - - 2005
We determined the ventilatory, cardiovascular and cerebral tissue oxygen response to two protocols of normobaric, isocapnic, intermittent hypoxia. Subjects (n = 18, male) were randomly assigned to short-duration intermittent hypoxia (SDIH, 12% O2 separated by 5 min of normoxia for 1 h) or long-duration intermittent hypoxia (LDIH, 30 min of ...
Berger Marc M MM Department of Internal Medicine VI (Clinical Pharmacology and Pharmacoepidemiology), University of Heidelberg, - - 2005
High-altitude pulmonary edema (HAPE) is characterized by excessive pulmonary vasoconstriction and is associated with decreased concentrations of nitric oxide (NO) in the lung. We hypothesized that individuals susceptible to HAPE (HAPE-S) would also have dysfunction of the vascular NO vasodilator pathway during hypoxia in the systemic vasculature. During normoxia (FI(O(2)) ...
Khodadadeh Bradley - - 2006
Our primary hypothesis was that the acute ventilatory response to carbon dioxide in the presence of sustained hypoxia {VRCO2 (hypoxia)} or hyperoxia {VRCO2 (hyperoxia)} would increase in subjects with obstructive sleep apnea (OSA) after exposure to episodic hypoxia. Secondarily, we hypothesized that chronic (i.e. years) exposure to episodic hypoxia, a ...
Kapoor Satwanti - - 2005
To understand the morphological and physiological variations among the temporary and permanent residents of high altitude, this study was undertaken at Leh, Ladakh. It is situated at 3500 m (11500 feet) above sea level, the mean barometric pressure was 500 tors and air temperature varied from 2 degrees C to ...
Kergoat Hélène - - 2005
PURPOSE: To investigate the effects of transient mild systemic hypoxia on the pulsatile ocular blood flow (POBF) in the healthy young adult. METHODS: Two measurements of the intraocular pressure (IOP) pulses, used to derive the POBF, were recorded from 19 subjects before, during, and after breathing 12% oxygen in nitrogen. ...
Baber Syed R - - 2005
Chronic alveolar hypoxia induces vascular changes leading to pulmonary hypertension. We investigated the role of nitric oxide synthase (NOS) on basal pulmonary artery pressure (PAP) and on changes in PAP arising from an acute alveolar hypoxic challenge (AAHC) in normoxic and chronically hypoxic young rabbits. The chronically hypoxic rabbits were ...
Fugelseth D - - 2005
OBJECTIVE: To assess the consequences of hypoxaemia and resuscitation with room air versus 100% O(2) on cardiac troponin I (cTnI), cardiac output (CO), and pulmonary artery pressure (PAP) in newborn pigs. DESIGN: Twenty anaesthetised pigs (12-36 hours; 1.7-2.7 kg) were subjected to hypoxaemia by ventilation with 8% O(2). When mean ...
Perimenis Petros - - 2005
Exposure to high altitude causes alveolar hypoxia and induces pulmonary hypertension (PH) with consequent limitation of exercise capacity. To assess the impact of sildenafil on haemodynamic and clinical parameters, and on aerobic performance, 12 young healthy unacclimatised subjects were studied (6 received sildenafil 40 mg t.i.d. and 6 received placebo) ...
Deboeck Gaël - - 2005
PURPOSE: High altitude exposure has consistently been reported to decrease forced vital capacity (FVC), but the mechanisms accounting for this observation remain incompletely understood. We investigated the possible contribution of a hypoxia-related decrease in respiratory muscle strength. METHODS: Maximal inspiratory and expiratory pressures (MIP and MEP), sniff nasal inspiratory pressure ...
Norcliffe L J - - 2005
Cerebral blood flow is known to increase in response to hypoxia and to decrease with hypocapnia. It is not known, however, whether these responses are altered in high-altitude dwellers who are not only chronically hypoxic and hypocapnic, but also polycythaemic. Here we examined cerebral blood flow responses to hypoxia and ...
Perry S F - - 2005
Circulating catecholamine levels and a variety of cardiorespiratory variables were monitored in cannulated bimodally breathing African lungfish (Protopterus dolloi) exposed to aquatic or aerial hypoxia. Owing to the purported absence of external branchial chemoreceptors in lungfish and the minor role played by the gill in O2 uptake, it was hypothesized ...
Bakr Ahmad F - - 2005
The aim of the study was to establish normal values of pulse oximetry saturation, respiratory rate, heart rate, and blood pressure in healthy newborns at high altitude. Vital signs and oximetry saturation readings were collected from healthy term newborns at birth, at 1 h, and at 24 h of life. ...
Yuyama Hironori - - 2005
The preventive effects of the novel and selective endothelin ET(A) receptor antagonist YM598 on the development of pulmonary hypertension (PH) were investigated in chronic hypoxia-induced PH rats. Oral administration of YM598 at a dose of 1 mg/kg was started on the first day of chronic hypoxia exposure for 2 and ...
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