Using Salivary Biomarkers for Stress Assessment in Offshore Saturation Diving: A Pilot Study.

Health monitoring during offshore saturation diving is complicated due to restricted access to the divers, the desire to keep invasive procedures to a minimum, and limited opportunity for laboratory work onboard dive support vessels (DSV). In this pilot study, we examined whether measuring salivary biomarkrers in samples collected by the divers themselves might be a feasible approach to environmental stress assessment. Nine saturation divers were trained in the passive drool method for saliva collection and proceeded to collect samples at nine time points before, during, and after an offshore commercial saturation diving campaign. Samples collected within the hyperbaric living chambers were decompressed and stored frozen at -20°C onboard the DSV until they were shipped to land for analysis. Passive drool samples were collected without loss and assayed for a selection of salivary biomarkers: secretory immunoglobulin A (SIgA), C-reactive protein (CRP), tumor necrosis factor (TNF)-α, interleukins IL-6, IL-8, IL-1β, as well as cortisol and alpha-amylase. During the bottom phase of the hyperbaric saturation, SIgA, CRP, TNF-α, IL-8 and IL-1β increased significantly, whereas IL-6, cortisol and alpha-amylase were unchanged. All markers returned to pre-dive levels after the divers were decompressed back to surface pressure. We conclude that salivary biomarker analysis may be a feasible approach to stress assessment in offshore saturation diving. The results of our pilot test are consonant with an activation of the sympathetic nervous system related to systemic inflammation during hyperbaric and hyperoxic saturation. [Abstract copyright: Copyright © 2021 Monnoyer, Lautridou, Deb, Hjelde and Eftedal.

Hemoglobin during and following a 4-week commercial saturation dive to 200 meters

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Functional profiling reveals altered metabolic activity in divers’ oral microbiota during commercial heliox saturation diving

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What happens in the oral cavity of divers during commercial saturation diving? Environmental adaptations of the oral microbiota and effects on the divers’ physiology: analysis of the metagenome and salivary stress biomarkers.

Commercial saturation diving has been used by the offshore oil and gas industry in the North Sea since the 1960s to perform long-term underwater work safely and efficiently. The highpressure oxygen conditions of the confined environment of the hyperbaric chamber bring challenging restraints, whether physiological or technical. Studies of basic pathophysiology in saturation diving have usually been done on the blood. However, phlebotomy is an invasive method and may add unnecessary supplementary risks of stress or infection for the divers. Using saliva not only makes it possible to bypass the technical problems specific to blood testing; it also gives access to information on the microorganisms present in the oral cavity. The variety of microorganisms living in and on the diver’s body, named microbiota, may influence the diver’s state of health. During saturation diving operations, microorganisms inhabiting the oral cavity of the divers are also exposed to the hyperbaric hyperoxic environment. The acclimatization of these microorganisms to the hyperbaric environment can impact central metabolic processes involved in the maintenance of physiological and metabolic homeostasis of the diver. The thesis addresses the effects of prolonged exposure to the high partial pressure of oxygen on the oral microbiota of thirty occupational saturation divers. Using 16S rRNA gene sequencing, we described the bacterial diversity and changes in the bacterial composition of the oral cavity before, during, and after a 28-day heliox commercial saturation dive at 200 meters deep (paper I). Based on the sequencing data, we used a computational approach to estimate the functional activities associated with the bacterial composition of the oral microbiota during and after saturation diving compared to a pre-dive baseline (paper II). Additionally, we assessed the effects of saturation on the physiology of nine divers by measuring levels of salivary biological markers of oxidative stress and inflammation collected throughout a 14-day heliox saturation dive to a depth of 80 meters (paper III). Acclimatization of the oral microbiota to the high partial pressure of oxygen during hyperbaric saturation was demonstrated by a transient change in the relative abundance of aerobic versus anaerobic bacteria, resulting in reduced bacterial diversity (paper I). The shift between bacterial communities led to transient changes in several metabolic pathways involved in their survival and growth. A decrease observed in vitamin B12 biosynthesis reinforces the findings of the literature about requirements in vitamin B12 supplementation as part of the diver’s diet. This supplementation could help correct the mild anemia observed in the divers after saturation (paper II). Finally, the salivary biomarkers analysis showed an increased production of salivary inflammatory mediators probably reflecting the response of the autonomous nervous system to the high partial pressure of oxygen. The signs of inflammatory responses strengthen what had already been demonstrated on the divers’ blood in previous saturation diving studies (paper III). In conclusion, this work highlighted the impact of saturation diving on divers both on their oral microbiota and on their physiology via oral stress biomarkers. Our results show that the oral microbiota and its functional activity changed during saturation. Furthermore, we showed that saliva could be used to monitor the physiological stress experienced by the divers during saturation diving operations

Hemoglobin during and following a four-week commercial saturation dive to 200 meters

Commercial saturation divers must acclimatize to hyperbaric hyperoxia in their work environment, and subsequently readjust to breathing normal air when their period in saturation is over. In this study, we measured hemoglobin (Hb) during and following 4 weeks of heliox saturation diving in order to monitor anemia development and the time for Hb to recover post-saturation. Male commercial saturation divers reported their capillary blood Hb daily, before, and during 28 days of heliox saturation to a working depth of circa 200 m (n = 11), and for 12 days at surface post-saturation (n = 9–7), using HemoCue 201+ Hb devices. Hb remained in normal range during the bottom phase, but fell during the decompression; reaching levels of mild anemia (≤13.6 g/dl) the day after the divers’ return to the surface. Hb was significantly lower than the pre-saturation baseline (14.7 ± 1.1 g/dl) on the fifth day post-saturation (12.8 ± 1.8 g/dl, p = 0.028), before reverting to normal after 6–7 days. At the end of the 12-day post-saturation period, Hb was not statistically different from the pre-saturation baseline. The observed Hb changes, although significant, were modest. While we cannot rule out effect of other factors, the presence of mild anemia may partially explain the transient fatigue that commercial saturation divers experience post-saturation

Shifts in the oral microbiota during a four-week commercial saturation dive to 200 meters

During commercial saturation diving, divers live and work under hyperbaric and hyperoxic conditions. The myriads of bacteria that live in and on the human body must adjust to the resultant hyperbaric stress. In this study, we examined the shifts in bacterial content in the oral cavity of saturation divers, using a metagenomic approach to determine the diversity in the composition of bacterial phyla and genera in saliva from 23 male divers before, during, and immediately after four weeks of commercial heliox saturation diving to a working depth of circa 200 meters. We found that the bacterial diversity fell during saturation, and there was a change in bacterial composition; with a decrease at the phylum level of obligate anaerobe Fusobacteria, and an increase of the relative abundance of Actinobacteria and Proteobacteria. At the genus level, Fusobacterium, Leptotrichia, Oribacterium, and Veillonella decreased whereas Neisseria and Rothia increased. However, at the end of the decompression both the diversity and composition of the microbiota returned to pre-dive values. The results indicate that the hyperoxic conditions during saturation may suppress the activity of anaerobes, leaving a niche for other bacteria to fill. The transient nature of the change could imply that hyperbaric heliox saturation has no lasting effect on the oral microbiota, but it is unknown whether or how a shift in oral bacterial diversity and abundance during saturation might impact the divers’ health or wellbeing

Effects of AMPD1 common mutation on the metabolic-chronotropic relationship: Insights from patients with myoadenylate deaminase deficiency.

Current evidence indicates that the common AMPD1 gene variant is associated with improved survival in patients with advanced heart failure. Whilst adenosine has been recognized to mediate the cardioprotective effect of C34T AMPD1, the precise pathophysiologic mechanism involved remains undefined to date. To address this issue, we used cardio-pulmonary exercise testing data (CPX) from subjects with myoadenylate deaminase (MAD) defects.From 2009 to 2013, all the patients referred in our laboratory to perform a metabolic exercise testing, i.e. a CPX with measurements of muscle metabolites in plasma during and after exercise testing, were prospectively enrolled. Subjects that also underwent an open muscle biopsy for diagnosis purpose were finally included. The metabolic-chronotropic response was assessed by calculating the slope of the linear relationship between the percent heart rate reserve and the percent metabolic reserve throughout exercise. MAD activity was measured using the Fishbein's technique in muscle biopsy sample. The common AMPD1 mutation was genotyped and the AMPD1 gene was sequenced to screen rare variants from blood DNA.Sixty-seven patients were included in the study; 5 had complete MAD deficiency, 11 had partial MAD deficiency, and 51 had normal MAD activity. Compared with normal MAD activity subjects, MAD deficient subjects appeared to have a lower-than-expected metabolic-chronotopic response during exercise. The metabolic-chronotropic relationship is more closely correlated with MAD activity in skeletal muscle (Rs = 0.57, p = 5.93E-7, Spearman correlation) than the presence of the common AMPD1 gene variant (Rs = 0.34, p = 0.005). Age-predicted O2 pulse ratio is significantly increased in MAD deficient subjects, indicating a greater efficiency of the cardiovascular system to deliver O2 (p < 0.01, Scheffé's post hoc test).The metabolic-chronotropic response is decreased in skeletal muscle MAD deficiency, suggesting a biological mechanism by which AMPD1 gene exerts cardiac effect