Publications
Une sélection de publications scientifiques portant sur la médecine et la physiologie de la plongée.
2013 août 15
Effect of a single, open-sea, air scuba dive on human micro- and macrovascular function
Lambrechts K, Pontier JM, Balestra C, Mazur A, Wang Q, Buzzacott P, Theron M, Mansourati J & Guerrero F.

PURPOSE: Previous studies have shown that bubble formation induced endothelial damage on conduit arteries. We aim to evaluate the effect of diving on microvascular and macrovascular function. METHODS: Nine divers took part in a SCUBA dive at 30 msw (400 kPa), for 30 min of bottom time. Pre- and post-dive, they underwent an assessment of endothelial-dependent (acetylcholine) and endothelial-independent (sodium nitroprusside) microvascular function (laser Doppler flowmetry), as well as endothelial-dependent (flow-mediated dilation) and endothelial-independent (nitroglycerin-mediated dilation) function. Bubble grades were monitored with Doppler according to the Spencer grade.

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2013 juin 18
Effect of tetrahydrobiopterin and exercise training on endothelium-dependent vasorelaxation in SHR
Guerrero F, Thioub S, Goanvec C, Theunissen S, Feray A, Balestra C, Mansourati J.

We examined whether the improvement of impaired NO-dependent vasorelaxation by exercise training could be mediated through a BH4-dependent mechanism. Male spontaneously hypertensive rats (SHR, n = 20) and Wistar-Kyoto rats (WKY, n = 20) were trained (Tr) for 9 weeks on a treadmill and compared to age-matched sedentary animals (Sed). Endothelium-dependent vasorelaxation (EDV) was assessed with acetylcholine by measuring isometric tension in rings of femoral artery precontracted with 10(-5) M phenylephrine. EDV was impaired in SHR-Sed as compared to WKY-Sed (p = 0.02). Training alone improved EDV in both WKY (p = 0.01) and SHR (p = 0.0001). Moreover, EDV was not different in trained SHR than in trained WKY (p = 0.934). Pretreatment of rings with L-NAME (50 μM) cancelled the difference in ACh-induced relaxation between all groups, suggesting that NO pathway is involved in these differences. The presence of 10(-5) M BH4 in the organ bath significantly improved EDV for sedentary SHR (p = 0.030) but not WKY group (p = 0.815). Exercise training turned the beneficial effect of BH4 on SHR to impairment of ACh-induced vasorelaxation in both SHR-Tr (p = 0.01) and WKY-Tr groups (p = 0.04). These results suggest that beneficial effect of exercise training on endothelial function is due partly to a BH4-dependent mechanism in established hypertension.

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2012 sept. 26
Effect of tetrahydrobiopterin and exercise training on endothelium-dependent vasorelaxation in SHR_V2
Guerrero F, Thioub S, Goanvec C, Theunissen S, Feray A, Balestra C & Mansourati J.

We examined whether the improvement of impaired NO-dependent vasorelaxation by exercise training could be mediated through a BH4-dependent mechanism. Male spontaneously hypertensive rats (SHR, n = 20) and Wistar-Kyoto rats (WKY, n = 20) were trained (Tr) for 9 weeks on a treadmill and compared to age-matched sedentary animals (Sed). Endothelium-dependent vasorelaxation (EDV) was assessed with acetylcholine by measuring isometric tension in rings of femoral artery precontracted with 10(-5) M phenylephrine. EDV was impaired in SHR-Sed as compared to WKY-Sed (p = 0.02).

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2007 nov. 30
Effect of varying deep stop times and shallow stop times on precordial bubbles after dives to 25 msw (82 fsw)
Bennett PB1, Marroni A, Cronje FJ, Cali-Corleo R, Germonpre P, Pieri M, Bonuccelli C, Leonardi MG, Balestra C.

In our previous research, a deep 5-min stop at 15 msw (50 fsw), in addition to the typical 3-5 min shallow stop, significantly reduced precordial Doppler detectable bubbles (PDDB) and "fast" tissue compartment gas tensions during decompression from a 25 msw (82 fsw) dive; the optimal ascent rate was 10 msw (30 fsw/min). Since publication of these results, several recreational diving agencies have recommended empirical stop times shorter than the 5 min stops that we used, stops of as little as 1 min (deep) and 2 min (shallow). In our present study, we clarified the optimal time for stops by measuring PDDB with several combinations of deep and shallow stop times following single and repetitive open-water dives to 25 msw (82 fsw) for 25 mins and 20 minutes respectively; ascent rate was 10 msw/min (33 fsw). Among 15 profiles, stop time ranged from 1 to 10 min for both the deep stops (15 msw/50 fsw) and the shallow stops (6 msw/20 fsw). Dives with 2 1/2 min deep stops yielded the lowest PDDB scores--shorter or longer deep stops were less effective in reducing PDDB. The results confirm that a deep stop of 1 min is too short--it produced the highest PDDB scores of all the dives. We also evaluated shallow stop times of 5, 4, 3, 2 and 1 min while keeping a fixed time of 2.5 min for the deep stop; increased times up to 10 min at the shallow stop did not further reduce PDDB. While our findings cannot be extrapolated beyond these dive profiles without further study, we recommend a deep stop of at least 2 1/2 mins at 15 msw (50 fsw) in addition to the customary 6 msw (20 fsw) for 3-5 mins for 25 meter dives of 20 to 25 minutes to reduce PDDB.

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2016 mai 12
Effects of oxygen-enriched air on cognitive performance during SCUBA-diving – an open-water study
Brebeck A. K., Deussen A., Schmitz-Peiffer H., Range U., Balestra C., Cleveland S., Schipke J. D.

Backround: Nitrogen narcosis impairs cognitive function, a fact relevant during SCUBA-diving. Oxygen-enriched air (nitrox) became popular in recreational diving, while evidence of its advantages over air is limited. AIM: Compare effects of nitrox28 and air on two psychometric tests.

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