Hypobaric hypoxia (HH) during airline travel induces several (patho-) physiological reactions in the human body. Whereas severe hypoxia is investigated thoroughly, very little is known about effects of moderate or short-term hypoxia, e.g. during airline flights. The aim of the present study was to analyse changes in serum protein expression and activation of signalling cascades in human volunteers staying for 30 min in a simulated altitude equivalent to airline travel. After approval of the local ethics committee, 10 participants were exposed to moderate hypoxia (simulation of 2400 m or 8000 ft for 30 min) in a hypobaric pressure chamber. Before and after hypobaric hypoxia, serum was drawn, centrifuged, and analysed by two-dimensional gel electrophoresis (2-DIGE) and matrix-assisted laser desorption/ionization followed by time-of-flight mass spectrometry (MALDI-TOF). Biological functions of regulated proteins were identified using functional network analysis (GeneMania^®, STRING^®, and Perseus^® software). In participants, oxygen saturation decreased from 98.1 ± 1.3% to 89.2 ± 1.8% during HH. Expression of 14 spots (i.e., 10 proteins: ALB, PGK1, APOE, GAPDH, C1QA, C1QB, CAT, CA1, F2, and CLU) was significantly altered. Bioinformatic analysis revealed an association of the altered proteins with the signalling cascades “regulation of haemostasis” (four proteins), “metabolism” (five proteins), and “leukocyte mediated immune response” (five proteins). Even though hypobaric hypoxia was short and moderate (comparable to an airliner flight), analysis of protein expression in human subjects revealed an association to immune response, protein metabolism, and haemostasis

The human body reacts to hypobaric hypoxia, e.g., during a stay at high altitude, with several mechanisms of adaption. Even short-time exposition to hypobaric hypoxia leads to complex adaptions. Proteomics facilitates the possibility to detect changes in metabolism due to changes in proteins. The present study aims to identify time-dependent changes in protein expression due to hypobaric hypoxia for 30 and 60 min at a simulated altitude of 15,000 ft. N = 80 male subjects were randomized and assigned into four different groups: 40 subjects to ground control for 30 (GC30) and 60 min (GC60) and 40 subjects to 15,000 ft for 30 (HH30) and 60 min (HH60). Subjects in HH30 and HH60 were exposed to hypobaric hypoxia in a pressure chamber (total pressure: 572 hPa) equivalent to 15,000 ft for 30 vs. 60 min, respectively. Drawn blood was centrifuged and plasma frozen (−80 °C) until proteomic analysis. After separation of high abundant proteins, protein expression was analyzed by 2-DIGE and MALDI-TOF. To visualize the connected signaling cascade, a bio-informatical network analysis was performed. The present study was approved by the ethical committee of the University of Cologne, Germany. The study registry number is NCT03823677. In comparing HH30 to GC30, a total of seven protein spots had a doubled expression, and 22 spots had decreased gene expression. In a comparison of HH60 to GC60, a total of 27 protein spots were significantly higher expressed. HH60, as compared to GC30, revealed that a total of 37 spots had doubled expression. Vice versa, 12 spots were detected, which were higher expressed in GC30 vs. HH60. In comparison to GC, HH60 had distinct differences in the number of differential protein spots (noticeably more proteins due to longer exposure to hypoxia). There are indicators that changes in proteins are dependent on the length of hypobaric hypoxia. Some proteins associated with hemostasis were differentially expressed in the 60 min comparison.

Introduction: Obstructive sleep apnea syndrome (OSAS) is associated with an increased cardiovascular risk. The underlying mechanisms are largely unclear. MicroRNAs (miRNAs) are RNAs circulating in the blood that can be released into the bloodstream during hypoxia. In the present study, we investigate if OSAS-induced hypoxia results in a release of miRNAs that may mediate OSAS-associated cardiovascular damage. Methods: Blood was sampled from 23 OSAS patients before and after a polygraphically monitored night. Total circulating RNA was isolated from the plasma and quantified using real-time qPCR. Using a Taqman miRNA array, the levels of 384 different miRNAs were compared between evening and morning after polysomnography. The most highly upregulated miRNA (miRNA-505) and four additionally upregulated miRNAs (miRNA-127, miRNA-133a, miRNA-145, and miRNA-181a) were then quantified in a bigger patient cohort individually. Results: Apnea/Hypopnea-Index (AHI) was evaluated and averaged at 26 per hour on nocturnal polygraphy. In an initial miRNA array, a total of 4 miRNAs were significantly regulated. A significant increase of miRNA-145 was observed in the larger patient cohort. No significant changes in concentration were detected for miRNA-127, miRNA-133a, miRNA-181a, and miRNA-505 in this larger cohort. Conclusion: OSAS results in the nocturnal release of miRNAs into the bloodstream. Our collected data may indicate a hypoxia-induced release of miRNAs into the bloodstream of OSAS-patients. In vitro experiments are needed to confirm the secretion of these miRNAs under hypoxia and evaluate the effect on the cardio vasculature.

Hintergrund Verglichen mit dem Zugewinn an Lebensqualität, den viele Patienten durch ein Cochlea-Implantat (CI) erfahren, bringt das CI nur wenige Einschränkungen im täglichen Leben mit sich. Doch kann man mit einem CI auch Tauchen und Fliegen? Halten das operierte Ohr sowie das Implantat selbst den ausgeprägten Druckveränderungen stand? Bisher gibt es keine klaren Empfehlungen und sehr wenig Literatur über die Risiken des Gerätetauchens sowie des Fliegens mit CI. Material und Methoden In einer hypo-/hyperbaren Druckkammer wurden Menschen mit einem CI einem Druckprofil mit Phasen des Druckanstiegs sowie Phasen des Druckabfalls ausgesetzt, sodass zunächst ein Flug und dann ein Tauchgang simuliert wurden. Sowohl vor als auch nach der Druckkammermessung erfolgten eine Ohrmikroskopie sowie eine Messung der Impedanzen des Cochlea-Implantats. Zusätzlich füllte jeder Patient einen symptombezogenen Fragebogen vor sowie nach der Druckkammermessung aus. Ergebnisse In der Druckkammer wurden insgesamt 17 CI-implantierte Ohren bei 11 Probanden untersucht. Zwei Drittel der Probanden gaben an, während der Untersuchung leichte Beschwerden gehabt zu haben. Bei einem Probanden musste die Messung aufgrund von Schmerzen abgebrochen werden. Sieben Patienten zeigten im Anschluss an die Druckexposition eine Hammergefäßinjektion in der Ohrmikroskopie. Bei keinem der Patienten kam es nach der Untersuchung zu einer subjektiven Hörverschlechterung. Es kam zu keiner relevanten Änderung der Impedanzen des CI-Implantats. Schlussfolgerung Die Exposition mit Unter- und Überdruck bei Patienten mit Cochlea-Implantaten ergab in der objektiven Überprüfung der Impedanzen keine wesentliche Abweichung der Impedanzen, sodass keine erneute Anpassung notwendig war. Allerdings zeigten sich leichtgradige Barotraumata sowie subjektive, leichte Beschwerden. Weitere Studien sind erforderlich, um eine adäquate Risikoeinschätzung zur Druckexposition bei CI-Trägern geben zu können. Objective Complications after cochlear implantation are relatively rare but patients are asked to follow certain behavioral rules. Until now there is no evidence if pressure changes that occur during flying and diving are safe for patients after cochlear implantation. For example, no recommendation exists for SCUBA- diving activities. Materials and Methods In a hypo-/hyperbaric pressure chamber patients after cochlear implantation were exposed to a standardized profile of decompression and compression simulating a flight in a common airplane and a dive. Pre and after the exposure in the pressure chamber, ENT examination and a control of impedances of the cochlear implant were performed. Additionally, patients filled in a questionnaire about complaints they had experienced in the pressure chamber or after. Results A total of 11 subjects (17 ears with CI) were examined in the pressure chamber. 2/3 of the subjects stated that they had slight complaints during the examination. Only in one patient the measurement needed to be stopped due to pain. Seven patients showed a vascular injection of the malleus in ear microscopy. In none of the patients there was a subjective change in hearing after the examination. Objective measurements of the impedance did not show relevant changes. Conclusion The exposure of cochlear implanted patients to overpressure and underpressure in a pressure chamber did not result in any significant deviation of the impedances, so that no further adjustment was necessary. Since there are no certified in vivo studies on pressure changes while diving and flying with a cochlear implant, further studies are required in order to be able to adequately advise CI patients about diving and flying. Received: 24 October 2020 Accepted: 04 January 2021 Publication Date: 26 January 2021 (online) © 2021. Thieme. All rights reserved. Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany