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Minerva Anestesiologica Jan 2019Xenon is a colorless and odorless noble gas, licensed for human use as an anesthetic gas as well as a radiological marker. The MAC of this gas is about 63% but xenon... (Review)
Review
Xenon is a colorless and odorless noble gas, licensed for human use as an anesthetic gas as well as a radiological marker. The MAC of this gas is about 63% but xenon anesthesia is associated with fast recovery of cognitive function and cardiovascular stability. Nevertheless, postoperative nausea and vomiting (PONV) incidence for xenon anesthesia is very high. It has been reported that Xenon has cytoprotective effects that may have therapeutic values in both CNS protection, and in organ graft preservation. Currently, there are few studies about the effect of xenon on ischemia reperfusion injury of transplantable organs and insufficient clinical data upon its effect on intracranial and cerebral perfusion pressure. We shortly review the pros and cons of xenon as an anesthetic agent.
Topics: Anesthesia Recovery Period; Anesthesia, Inhalation; Anesthetics, Inhalation; Emergence Delirium; Humans; Postoperative Nausea and Vomiting; Xenon
PubMed: 30019577
DOI: 10.23736/S0375-9393.18.12909-9 -
Science Translational Medicine Aug 2013One challenging aspect of the clinical assessment of brain-injured, unresponsive patients is the lack of an objective measure of consciousness that is independent of the...
One challenging aspect of the clinical assessment of brain-injured, unresponsive patients is the lack of an objective measure of consciousness that is independent of the subject's ability to interact with the external environment. Theoretical considerations suggest that consciousness depends on the brain's ability to support complex activity patterns that are, at once, distributed among interacting cortical areas (integrated) and differentiated in space and time (information-rich). We introduce and test a theory-driven index of the level of consciousness called the perturbational complexity index (PCI). PCI is calculated by (i) perturbing the cortex with transcranial magnetic stimulation (TMS) to engage distributed interactions in the brain (integration) and (ii) compressing the spatiotemporal pattern of these electrocortical responses to measure their algorithmic complexity (information). We test PCI on a large data set of TMS-evoked potentials recorded in healthy subjects during wakefulness, dreaming, nonrapid eye movement sleep, and different levels of sedation induced by anesthetic agents (midazolam, xenon, and propofol), as well as in patients who had emerged from coma (vegetative state, minimally conscious state, and locked-in syndrome). PCI reliably discriminated the level of consciousness in single individuals during wakefulness, sleep, and anesthesia, as well as in patients who had emerged from coma and recovered a minimal level of consciousness. PCI can potentially be used for objective determination of the level of consciousness at the bedside.
Topics: Anesthetics; Brain; Consciousness; Evoked Potentials; Female; Humans; Male; Midazolam; Propofol; Transcranial Magnetic Stimulation; Xenon
PubMed: 23946194
DOI: 10.1126/scitranslmed.3006294 -
Anesthesiology Dec 2017
Topics: Anesthetics, Inhalation; Xenon
PubMed: 28872481
DOI: 10.1097/ALN.0000000000001874 -
Progress in Nuclear Magnetic Resonance... Feb 2021Hyperpolarised gas lung MRI using xenon-129 can provide detailed 3D images of the ventilated lung airspaces, and can be applied to quantify lung microstructure and... (Review)
Review
Hyperpolarised gas lung MRI using xenon-129 can provide detailed 3D images of the ventilated lung airspaces, and can be applied to quantify lung microstructure and detailed aspects of lung function such as gas exchange. It is sensitive to functional and structural changes in early lung disease and can be used in longitudinal studies of disease progression and therapy response. The ability of Xe to dissolve into the blood stream and its chemical shift sensitivity to its local environment allow monitoring of gas exchange in the lungs, perfusion of the brain and kidneys, and blood oxygenation. This article reviews the methods and applications of in vivoXe MR in humans, with a focus on the physics of polarisation by optical pumping, radiofrequency coil and pulse sequence design, and the in vivo applications of Xe MRI and MRS to examine lung ventilation, microstructure and gas exchange, blood oxygenation, and perfusion of the brain and kidneys.
Topics: Humans; Lung; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Xenon Isotopes
PubMed: 33632417
DOI: 10.1016/j.pnmrs.2020.11.002 -
Molecules (Basel, Switzerland) Nov 2022Although critical for development of novel therapies, understanding altered lung function in disease models is challenging because the transport and diffusion of gases... (Review)
Review
Although critical for development of novel therapies, understanding altered lung function in disease models is challenging because the transport and diffusion of gases over short distances, on which proper function relies, is not readily visualized. In this review we summarize progress introducing hyperpolarized Xe imaging as a method to follow these processes in vivo. The work is organized in sections highlighting methods to observe the gas replacement effects of breathing (Gas Dynamics during the Breathing Cycle) and gas diffusion throughout the parenchymal airspaces (3). We then describe the spectral signatures indicative of gas dissolution and uptake (4), and how these features can be used to follow the gas as it enters the tissue and capillary bed, is taken up by hemoglobin in the red blood cells (5), re-enters the gas phase prior to exhalation (6), or is carried via the vasculature to other organs and body structures (7). We conclude with a discussion of practical imaging and spectroscopy techniques that deliver quantifiable metrics despite the small size, rapid motion and decay of signal and coherence characteristic of the magnetically inhomogeneous lung in preclinical models (8).
Topics: Xenon Isotopes; Magnetic Resonance Imaging; Lung; Respiration; Erythrocytes
PubMed: 36500430
DOI: 10.3390/molecules27238338 -
Circulation Research Apr 2022There is an increased appreciation for the importance of the right heart and pulmonary circulation in several disease states across the spectrum of pulmonary... (Review)
Review
There is an increased appreciation for the importance of the right heart and pulmonary circulation in several disease states across the spectrum of pulmonary hypertension and left heart failure. However, assessment of the structure and function of the right heart and pulmonary circulation can be challenging, due to the complex geometry of the right ventricle, comorbid pulmonary airways and parenchymal disease, and the overlap of hemodynamic abnormalities with left heart failure. Several new and evolving imaging modalities interrogate the right heart and pulmonary circulation with greater diagnostic precision. Echocardiographic approaches such as speckle-tracking and 3-dimensional imaging provide detailed assessments of regional systolic and diastolic function and volumetric assessments. Magnetic resonance approaches can provide high-resolution views of cardiac structure/function, tissue characterization, and perfusion through the pulmonary vasculature. Molecular imaging with positron emission tomography allows an assessment of specific pathobiologically relevant targets in the right heart and pulmonary circulation. Machine learning analysis of high-resolution computed tomographic lung scans permits quantitative morphometry of the lung circulation without intravenous contrast. Inhaled magnetic resonance imaging probes, such as hyperpolarized 129Xe magnetic resonance imaging, report on pulmonary gas exchange and pulmonary capillary hemodynamics. These approaches provide important information on right ventricular structure and function along with perfusion through the pulmonary circulation. At this time, the majority of these developing technologies have yet to be clinically validated, with few studies demonstrating the utility of these imaging biomarkers for diagnosis or monitoring disease. These technologies hold promise for earlier diagnosis and noninvasive monitoring of right heart failure and pulmonary hypertension that will aid in preclinical studies, enhance patient selection and provide surrogate end points in clinical trials, and ultimately improve bedside care.
Topics: Heart Failure; Humans; Hypertension, Pulmonary; Pulmonary Circulation; Xenon Isotopes
PubMed: 35482838
DOI: 10.1161/CIRCRESAHA.121.319990 -
Minerva Anestesiologica Jun 2011
Topics: Animals; Apoptosis; Brain; Xenon
PubMed: 21467964
DOI: No ID Found -
Journal of Affective Disorders Mar 2022Stroke is a life-changing event as stroke survivors experience changes in personality, emotions and mood. We investigated the effect of xenon gas encapsulated in...
Stroke is a life-changing event as stroke survivors experience changes in personality, emotions and mood. We investigated the effect of xenon gas encapsulated in liposomes on stroke-generated sensorimotor impairments, and anxiety- and depression-like phenotypes. Ischemic stroke was created by the intraluminal middle cerebral artery occlusion (MCAO) for 6 h followed by reperfusion in rats. Xenon-liposome (6 mg/kg, intravenous) treatment was given multiple times starting at 2 h post-ischemia through 6 h (5X), and once-daily for next 3 days. Rats underwent ischemic injury displayed sensorimotor deficits in the adhesive removal, vibrissae-evoked forelimb placement and rotarod tests. These animals also made lesser entries and spent less time on open arms of the elevated-plus maze and swam more in passive mode in the forced swimming test, indicating anxiety- and depression-like behaviors at 28- and 35-days post-injury, respectively. Repeated intravenous treatment with xenon-liposomes ameliorated these behavioral aberrations (p < 0.05). Gut microbiome analysis (16S ribosomal-RNA gene sequencing) showed a decrease in the Clostridium clusters XI, XIVa, XVIII and Lactobacillus bacterium, and increase of the Prevotella in the xenon-liposome group. No microbiota communities were majorly affected across the treatments. Moreover, xenon treatment group showed augmented plasma levels of IL-6 cytokines (∼5 fold) on day-35 post-ischemia, while no change was noticed in the IL-1β, IL-4, IL-10, IL-13 and MCP-1 levels. Our data highlights the safety, behavioral recovery and reversal of post-stroke brain injury following xenon-liposome treatment in an extended ischemic model. These results show the potential for this treatment strategy to be translated to patients with stroke.
Topics: Animals; Anxiety; Brain Injuries; Cytokines; Disease Models, Animal; Humans; Infarction, Middle Cerebral Artery; Rats; Xenon
PubMed: 34990636
DOI: 10.1016/j.jad.2022.01.025 -
Magnetic Resonance Imaging Clinics of... May 2015Functional imaging offers information more sensitive to changes in lung structure and function. Hyperpolarized helium ((3)He) and xenon ((129)Xe) MR imaging of the lungs... (Review)
Review
Functional imaging offers information more sensitive to changes in lung structure and function. Hyperpolarized helium ((3)He) and xenon ((129)Xe) MR imaging of the lungs provides sensitive contrast mechanisms to probe changes in pulmonary ventilation, microstructure, and gas exchange. Gas imaging has shifted to the use of (129)Xe. Xenon is well-tolerated. (129)Xe is soluble in pulmonary tissue, which allows exploring specific lung function characteristics involved in gas exchange and alveolar oxygenation. Hyperpolarized gases and (129)Xe in particular stand to be an excellent probe of pulmonary structure and function, and provide sensitive and noninvasive biomarkers for pulmonary diseases.
Topics: Diffusion Magnetic Resonance Imaging; Helium; Humans; Isotopes; Lung; Magnetic Resonance Imaging; Pulmonary Gas Exchange; Xenon Isotopes
PubMed: 25952516
DOI: 10.1016/j.mric.2015.01.003 -
Biophysical Journal Dec 2022Protein interiors contain void space that can bind small gas molecules. Determination of gas pathways and kinetics in proteins has been an intriguing and challenging...
Protein interiors contain void space that can bind small gas molecules. Determination of gas pathways and kinetics in proteins has been an intriguing and challenging task. Here, we combined computational methods and the hyperpolarized xenon-129 chemical exchange saturation transfer (hyper-CEST) NMR technique to investigate xenon (Xe) exchange kinetics in maltose-binding protein (MBP). A salt bridge ∼9 Å from the Xe-binding site formed upon maltose binding and slowed the Xe exchange rate, leading to a hyper-CEST Xe signal from maltose-bound MBP. Xe dissociation occurred faster than dissociation of the salt bridge, as shown by C NMR spectroscopy and variable-B hyper-CEST experiments. "Xe flooding" molecular dynamics simulations identified a surface hydrophobic site, V23, that has good Xe binding affinity. Mutations at this site confirmed its role as a secondary exchange pathway in modulating Xe diffusion. This shows the possibility for site-specifically controlling xenon protein-solvent exchange. Analysis of the available MBP structures suggests a biological role of MBP's large hydrophobic cavity to accommodate structural changes associated with ligand binding and protein-protein interactions.
Topics: Xenon; Maltose-Binding Proteins
PubMed: 36271622
DOI: 10.1016/j.bpj.2022.10.025