Background: Several mechanisms allow humans to resist the extreme conditions encountered during breath-hold diving. Available nitric oxide (NO) is one of the major contributors to such complex adaptations at depth and oxidative stress is one of the major collateral effects of diving. Due to technical difficulties, these biomarkers have not so far been studied in vivo while at depth. The aim of this study is to investigate nitrate and nitrite (NOx) concentration, total antioxidant capacity (TAC) and lipid peroxidation (TBARS) before, during, and after repetitive breath-hold dives in healthy volunteers.
Materials and Methods: Blood plasma, obtained from 14 expert breath-hold divers, was tested for differences in NOx, TAC, and TBARS between pre-dive, bottom, surface, 30 and 60 min post-dive samples.
Objective vs. Subjective Evaluation of Cognitive Performance During 0.4-MPa Dives Breathing Air or Nitrox
Germonpré P., Balestra C., Hemelryck W., Buzzacott P., Lafère P.
BACKGROUND: Divers try to limit risks associated with their sport, for instance by breathing enriched air nitrox (EANx) instead of air. This double blinded, randomized trial was designed to see if the use of EANx could effectively improve cognitive performance while diving.
METHODS: Eight volunteers performed two no-decompression dry dives breathing air or EANx for 20 min at 0.4 MPa. Cognitive functions were assessed with a computerized test battery, including MathProc and Ptrail. Measurements were taken before the dive, upon arrival and after 15 min at depth, upon surfacing, and at 30 min postdive. After each dive subjects were asked to identify the gas they had just breathed.
Variability in circulating gas emboli after a same scuba diving exposure
Papadopoulou V., Germonpré P., Cosgrove D., Eckersley RJ., Dayton PA., Obeid G., Boutros A., Tang MX., Theunissen S., Balestra C.
A reduction in ambient pressure or decompression from scuba diving can result in ultrasound-detectable venous gas emboli (VGE). These environmental exposures carry a risk of decompression sickness (DCS) which is mitigated by adherence to decompression schedules; however, bubbles are routinely observed for dives well within these limits and significant inter-personal variability in DCS risk exists. Here, we assess the variability and evolution of VGE for 2 h post-dive using echocardiography, following a standardized pool dive in calm warm conditions.
Increasing Oxygen Partial Pressures Induce a Distinct Transcriptional Response in Human PBMC: A Pilot Study on the “Normobaric Oxygen Paradox”
Fratantonio D, Virgili F, Zucchi A, Lambrechts K, Latronico T, Lafère P, Germonpré P, Balestra C.
The term “normobaric oxygen paradox” (NOP), describes the response to the return to normoxia after a hyperoxic event, sensed by tissues as oxygen shortage, and resulting in up-regulation of the Hypoxia-inducible factor 1α (HIF-1α) transcription factor activity. The molecular characteristics of this response have not been yet fully characterized. Herein, we report the activation time trend of oxygen-sensitive transcription factors in human peripheral blood mononuclear cells (PBMCs) obtained from healthy subjects after one hour of exposure to mild (MH), high (HH) and very high (VHH) hyperoxia, corresponding to 30%, 100%, 140% O2, respectively.
Impaired Attentional Processing During Parabolic Flight
Friedl-Werner A, Machado M-L, Balestra C, Liegard Y, Philoxene B, Brauns K, Stahn AC, Hitier M, Besnard S.
Previous studies suggest that altered gravity levels during parabolic flight maneuvers affect spatial updating. Little is known about the impact of the experimental setting and psychological stressors associated with parabolic flight experiments on attentional processes. To address this gap, we investigated the level of alertness, selective and sustained attention in 1 and 0 g using a Go/No-Go Continuous Performance Task. We also identified several parameters associated with the experimental set-up of a parabolic flight that could be expected to affect attentional processing.
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