882 resultados para Intermittent aeration


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AIMS/HYPOTHESIS To investigate exercise-related fuel metabolism in intermittent high-intensity (IHE) and continuous moderate intensity (CONT) exercise in individuals with type 1 diabetes mellitus. METHODS In a prospective randomised open-label cross-over trial twelve male individuals with well-controlled type 1 diabetes underwent a 90 min iso-energetic cycling session at 50% maximal oxygen consumption ([Formula: see text]), with (IHE) or without (CONT) interspersed 10 s sprints every 10 min without insulin adaptation. Euglycaemia was maintained using oral (13)C-labelled glucose. (13)C Magnetic resonance spectroscopy (MRS) served to quantify hepatocellular and intramyocellular glycogen. Measurements of glucose kinetics (stable isotopes), hormones and metabolites complemented the investigation. RESULTS Glucose and insulin levels were comparable between interventions. Exogenous glucose requirements during the last 30 min of exercise were significantly lower in IHE (p = 0.02). Hepatic glucose output did not differ significantly between interventions, but glucose disposal was significantly lower in IHE (p < 0.05). There was no significant difference in glycogen consumption. Growth hormone, catecholamine and lactate levels were significantly higher in IHE (p < 0.05). CONCLUSIONS/INTERPRETATION IHE in individuals with type 1 diabetes without insulin adaptation reduced exogenous glucose requirements compared with CONT. The difference was not related to increased hepatic glucose output, nor to enhanced muscle glycogen utilisation, but to decreased glucose uptake. The lower glucose disposal in IHE implies a shift towards consumption of alternative substrates. These findings indicate a high flexibility of exercise-related fuel metabolism in type 1 diabetes, and point towards a novel and potentially beneficial role of IHE in these individuals. TRIAL REGISTRATION ClinicalTrials.gov NCT02068638 FUNDING: Swiss National Science Foundation (grant number 320030_149321/) and R&A Scherbarth Foundation (Switzerland).

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The United States Air Force School of Aerospace Medicine (USAFSAM) and Aeromedical Consult Service (ACS) have developed waiver criteria for pilots with subtle substandard depth perception. This is to allow United States Air Force (USAF) pilots with mild depth perception deficiency to continue flying duties while limiting the risk to flight safety and ensuring the availability of costly human resources. From 1999 to 2005, 166 aviators were given waivers for intermittent monofixation syndrome (IMFS). Of these, 96 were student pilots who performed slightly worse at stereoptic dependent flight maneuvers than student pilots (8,907) with normal depth perception (Lowry, 2006).^ This study's purpose is to evaluate the performance of the extended-trail maneuver, a non-stereoptic dependent flying maneuver, as executed by a cohort of 12 United States Air Force student pilots with intermittent monofixation syndrome versus the cohort of 100 student pilots with normal depth perception. These subjects are extracted from the cohorts examined by Lowry (2006) and the null hypothesis predicts no statistical difference in the performance of the non-stereoptic dependant flight maneuver extended-trail between student pilots with intermittent monofixation syndrome and those without the condition. ^

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Approximately 200,000 African children are born with sickle-cell anemia each year. Research has shown that individuals with hemoglobin disorders, particularly sickle-cell anemia, have increased susceptibility to contracting malaria. Currently it is recommended that patients diagnosed with sickle-cell anemia undergo malaria chemoprophylaxis in order to decrease their chances of malarial infection. However, studies have shown that routine administration of these drugs increases the risk of drug resistance and could possibly impair the development of naturally acquired immunity. Clinical trials have shown intermittent preventive treatment (IPT) to be an effective method of protection against malaria. The objective of this report was to review previously conducted clinical trials that study the effects of intermittent preventive treatment on malaria and anemia in infants and children. Based on the review, implications for its appropriateness as a protective measure against malaria for infants and children diagnosed with sickle-cell disease were provided.^ The 18 studies reviewed were randomized controlled trials that focused on IPT’s effect on malaria (7 studies), anemia (1 study), or both (8 studies). In addition to these 16, one study looks at IPT’s effect on molecular resistance to malaria, and another study is a follow-up to a study in order to review IPT’s potential to cause a rebound effect. The 18 th study in this review specifically looks at IPT’s protective efficacy in children with SCA. The studies in this report were restricted to randomized controlled trials that have been performed from 2000 to 2010. Reports on anemia were included to illustrate possible added benefits of the use of IPT specific to burdens associated with SCA other than malaria susceptibility. The outcomes of these studies address several issues of concern involving the administration of IPT: protective efficacy (in reference to age, seasonal versus perennial malaria regions, and overall effectiveness against malaria and anemia), drug resistance, drug rebound effect, drug side-effects, and long-term effects. Overall, these showed that IPT has a significant level of protective efficacy against malaria and/or anemia in children. More specifically, the IPT study evaluating children diagnosed with sickle-cell anemia proved IPT to be a more effective method of protection than traditional chemoprophylaxis. ^

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The spatial complexity of the distribution of organic matter, chemicals, nutrients, pollutants has been demonstrated to have multifractal nature (Kravchenco et al. [1]). This fact supports the possibility of existence of some emergent heterogeneity structure built under the evolution of the system. The aim of this note is providing a consistent explanation to the mentioned results via an extremely simple model.

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Funder statement This article/paper/report presents independent research funded by the National Institute for Health Research (NIHR). The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the UK Government’s Department of Health. Acknowledgements We would like to acknowledge Dr Graeme MacLennan, Mr Simon Skene, Mr Julian Shah and Dr Nadine Dougall (past member) for their valuable contribution to the study as DMC members. We would like to thank Professor Chris Butler, Dr Emma Hall, Mr Roland Morley, Mr Dan Wood, Ms Jane Laws and Ms Sarah Bittlestone for their oversight of the AnTIC study as members of the TSC, and we would like to thank Ms Heather Armstrong for her contributions as a patient group representative. We thank all Principal Investigators and site staff for their commitment in recruitment for the AnTIC study. Finally, we would like to thank Hazel Wilde for secretarial support. The trial is funded by the NIHR Health Technology Assessment Programme (project reference: 11-72-01) and will be published in full in the Health Technology Assessment journal series. The authors also acknowledge the support of the National Institute for Health Research through the Comprehensive Clinical Research Network.

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Neuronal apoptosis was observed in the rat dentate gyrus in two experimental models of human limbic epilepsy. Five hours after one hippocampal kindling stimulation, a marked increase of in situ terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling (TUNEL) of fragmented DNA was observed in nuclei located within and on the hilar border of the granule cell layer and in the polymorphic region. Forty kindling stimulations with 5-min interval produced higher numbers of labeled nuclei compared with one stimulation. The increase of TUNEL-positive nuclei was prevented by the protein synthesis inhibitor cycloheximide but not affected by the N-methyl-d-aspartate receptor antagonist MK-801. Kainic acid-induced seizures lead to a pattern of labeling in the hippocampal formation identical to that evoked by kindling. A large proportion of cells displaying TUNEL-positive nuclei was double-labeled by the neuron-specific antigen NeuN, demonstrating the neuronal identity of apoptotic cells. Either 1 or 40 kindling stimulations also gave rise to a marked increase of the number of cells double-labeled with the mitotic marker bromodeoxyuridine and NeuN in the subgranular zone and on the hilar border of the dentate granule cell layer. The present data show that single and intermittent, brief seizures induce both apoptotic death and proliferation of dentate gyrus neurons. We hypothesize that these processes, occurring early during epileptogenesis, are primary events in the development of hippocampal pathology in animals and possibly also in patients suffering from temporal lobe epilepsy.

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The response of the ascorbate-glutathione cycle was investigated in roots of young wheat (Triticum aestivum L.) seedlings that were deprived of oxygen either by subjecting them to root hypoxia or to entire plant anoxia and then re-aerated. Although higher total levels of ascorbate and glutathione were observed under hypoxia, only the total amount of ascorbate was increased under anoxia. Under both treatments a significant increase in the reduced form of ascorbate and glutathione was found, resulting in increased reduction states. Upon the onset of re-aeration the ratios started to decline rapidly, indicating oxidative stress. Hypoxia caused higher activity of ascorbate peroxidase, whereas activities of monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase were diminished or only slightly influenced. Under anoxia, activities of ascorbate peroxidase and glutathione reductase decreased significantly to 39 and 62%, respectively. However, after re-aeration of hypoxically or anoxically pretreated roots, activity of enzymes approached the control levels. This corresponds with the restoration of the high reduction state of ascorbate and glutathione within 16 to 96 h of re-aeration, depending on the previous duration of anoxia. Apparently, anoxia followed by re-aeration more severely impairs entire plant metabolism compared with hypoxia, thus leading to decreased viability.

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The rhythmogenesis of 10-Hz sleep spindles is studied in a large-scale thalamic network model with two cell populations: the excitatory thalamocortical (TC) relay neurons and the inhibitory nucleus reticularis thalami (RE) neurons. Spindle-like bursting oscillations emerge naturally from reciprocal interactions between TC and RE neurons. We find that the network oscillations can be synchronized coherently, even though the RE-TC connections are random and sparse, and even though individual neurons fire rebound bursts intermittently in time. When the fast gamma-aminobutyrate type A synaptic inhibition is blocked, synchronous slow oscillations resembling absence seizures are observed. Near-maximal network synchrony is established with even modest convergence in the RE-to-TC projection (as few as 5-10 RE inputs per TC cell suffice). The hyperpolarization-activated cation current (Ih) is found to provide a cellular basis for the intermittency of rebound bursting that is commonly observed in TC neurons during spindles. Such synchronous oscillations with intermittency can be maintained only with a significant degree of convergence for the TC-to-RE projection.

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Synchronization of growth rates are an important feature of international business cycles, particularly in relation to regional integration projects such as the single currency in Europe. Synchronization of growth rates clearly enhances the effectiveness of European Central Bank monetary policy, ensuring that policy changes are attuned to the dynamics of growth and business cycles in the majority of member states. In this paper a dissimilarity metric is constructed by measuring the topological differences between the GDP growth patterns in recurrence plots for individual countries. The results show that synchronization of growth rates were higher among the Euro area member states during the second half of the 1980s and from 1997 to roughly 2002. Apart from these two time periods, Euro area member states do not appear to be more synchronized than a group of major international countries, signifying that globalization was the major cause of international business cycle synchronization.