Éditeur(s) : HAL CCSD
Résumé : International audience
BACKGROUND: The effects of pressure-controlled (PC) ventilation on the ventilatory and haemodynamic parameters during laparoscopy procedures had not been carefully assessed. This prospective cross-over study was undertaken to compare how volume-controlled (VC) and PC modes could affect pulmonary mechanics, gas exchange, and cardiac function in patients undergoing laparoscopy. METHODS: Twenty-one patients undergoing laparoscopic urological procedures had their lungs ventilated at the beginning with VC ventilation. PC ventilation was instituted at the end of the VC sequence. Ventilator settings were adjusted to keep tidal volume, respiratory rate, and Fi(o(2)) constant in every mode. A complete set of ventilatory, haemodynamic, and gas exchange parameters was obtained under VC after 40 min of pneumoperitoneum and 20 min after switching for PC. Transoesophageal echocardiography was performed in order to evaluate systolic and diastolic function of the heart. RESULTS: When VC was switched to PC, peak airway pressure decreased [mean (sd) 32 (6) vs 27 (6) cm H(2)O; P < 0.0001], peak inspiratory flow increased [17 (3) vs 48 (8) litre min(-1); P < 0.0001), and dynamic compliance improved [+15 (8)%]. No difference was noted for static airway pressure, static compliance, and arterial oxygenation. No significant change could be demonstrated in the systolic [left ventricular end-systolic wall stress 66 (16) vs 63 (14) x 10(3) dyn cm(-2) m(-2)] or diastolic function [early diastolic velocity 10.3 (2.5) vs 10.5 (2.7) cm s(-1)]. CONCLUSIONS: In this study, no short-term beneficial effect of PC ventilation could be demonstrated over conventional VC ventilation in patients with pneumoperitoneum.
BJA

hal-00689758
https://hal.archives-ouvertes.fr/hal-00689758
DOI : 10.1093/bja/aem166
PUBMED : 17626027

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Different household insecticide applications via two electric vaporizers emitting transfluthrin were realized in a full-scale experimental room under controlled air exchange rate conditions. On-line high-time resolved measurements of the gas-phase concentrations of the active substance during and immediately after the spreading periods were performed with a High Sensitivity Proton-Transfer-Reaction Mass Spectrometer (HS-PTR-MS). Experimental and modelled data from the ConsExpo 4.0 software were also compared to evaluate the sources of differences. Different application scenarios were also compared. Averaged inhaled concentrations over 1h, 1week, and 5months were estimated to be 8.3, 1.8, and 1.8μg.m(-3), respectively. Corresponding margins of exposures range from 1000 to 10,000, claiming for the absence of effect. Dermal and dust ingestion pathways, although roughly estimated, seems being non-negligible. This claims for a more in-depth integrated risk assessment.
ISSN: 0160-4120

hal-00875320
https://hal-univ-rennes1.archives-ouvertes.fr/hal-00875320
https://hal-univ-rennes1.archives-ouvertes.fr/hal-00875320/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-00875320/file/Transfluthrin-indoor-accepted.pdf
DOI : 10.1016/j.envint.2013.07.011

Éditeur(s) : HAL CCSD
Résumé : International audience
To determine whether exercise modality affects arterial hypoxemia (EIAH) during training-intensity exercise, 13 triathletes performed 20 min of cycling (C) followed by 20 min of running (R): C-R, and two weeks later, 20 min of R followed by 20 min of C:R-C. Each trial was performed at an intensity slightly above the ventilatory threshold and close to the daily training intensity (75 % of VO2max). Ventilatory data were collected continuously using an automated breath-by-breath system. Partial pressure of oxygen in arterial blood (PaO2) was measured after each C and R segment and arterial oxyhemoglobin saturation (SpO2) was monitored continuously via pulse oximetry. The metabolic rate was similar across modalities and trials, i.e., C-R (53.8 +/- 3.8 vs. 51.1 +/- 5.3 ml.min(-1).kg(-1)) and R-C (52.2 +/- 4.5 vs. 53.2 +/- 4.6 ml.min(-1).kg (-1)). EIAH showed significantly greater severity for R compared to C irrespective of the order (p < 0.05 for both trials). R values of PaO2 (and SpO2) for C-R and R-C were 88.7 +/- 6.0 mm Hg (93.0 +/- 0.6 % SpO2) and 86.6 +/- 7.3 mm Hg (93.5 +/- 0.6 % SpO2) and C values were 93.7 +/- 8.4 mm Hg (95.4 +/- 0.4 % SpO2) and 91.4 +/- 5.4 mm Hg (94.8 +/- 0.3 % SpO2). R ventilatory data described a significantly different breathing pattern than C, with higher respiratory rate (35.9 b.min(-1) vs. 51.1 b.min(-1) for C-R, p < 0.01; and 50.0 b.min(-1) vs. 41.5 b.min(-1) for R-C, p < 0.01) and lower tidal volume (2636 ml vs. 2282 ml for C-R, p < 0.02 and 2272 ml vs. 2472 ml for R-C, p < 0.05). We concluded that EIAH was greater during running than cycling for a similar metabolic rate corresponding to training intensity and that EIAH could thus be considered dependent on exercise modality.
Internation Journal of Sports Medicine

hal-00720806
https://hal.univ-antilles.fr/hal-00720806
https://hal.univ-antilles.fr/hal-00720806/document
https://hal.univ-antilles.fr/hal-00720806/file/sm290.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
We have measured simultaneously the methane (CH4) and carbon dioxide (CO2) surface concentrations and water–air fluxes by floating chambers (FC) in the Petit-Saut Reservoir (French Guiana) and its tidal river (Sinnamary River) downstream of the dam, during the two field experiments in wet (May 2003) and dry season (December 2003). The eddy covariance (EC) technique was also used for CO2 fluxes on the lake. The comparison of fluxes obtained by FC and EC showed little discrepancies mainly due to differences in measurements durations which resulted in different average wind speeds. When comparing the gas transfer velocity (k600) for a given wind speed, both methods gave similar results. On the lake and excluding rainy events, we obtained an exponential relationship between k600 and U10, with a significant intercept at 1.7 cm h− 1, probably due to thermal effects. Gas transfer velocity was also positively related to rainfall rates reaching 26.5 cm h−1 for a rainfall rate of 36 mm h− 1. During a 24-h experiment in dry season, rainfall accounted for as much as 25% of the k600. In the river downstream of the dam, k600 values were 3 to 4 times higher than on the lake, and followed a linear relationship with U10.
ISSN: 0924-7963

hal-00519502
https://hal.archives-ouvertes.fr/hal-00519502
DOI : 10.1016/j.jmarsys.2006.03.019

Éditeur(s) : HAL CCSD Springer Verlag/EDP Sciences
Résumé : We characterised the among species variability in leaf gas exchange and morphological traits under controlled conditions of seedlings of 22 tropical rainforest canopy species to understand the origin of the variability in leaf carbon isotope discrimination (Delta) among species with different growth and dynamic characteristics (successional gradient). Our results first suggest that these species pursue a consistent strategy in terms of (Delta) throughout their ontogeny (juveniles grown here versus canopy adult trees from the natural forest). Second, leaf (Delta) was negatively correlated with WUE and N, and positively correlated with gs, but among species differences in (Delta) were mainly explained by differences in WUE. Finally, species belonging to different successional groups display distinct leaf functional and morphological traits. We confirmed that fast growing early successional species maximise carbon assimilation with high stomatal conductance. In contrast, fast and slow growing late successional species are both characterised by low carbon assimilation values, but by distinct stomatal conductance and leaf morphological features. Along the successional gradient, these differences result in much lower (Delta) for the intermediate species (i.e. fast growing late successional) as compared to the two other groups.
ISSN: 1286-4560

hal-01032038
https://hal.archives-ouvertes.fr/hal-01032038
DOI : 10.1051/forest:2006101

Éditeur(s) : HAL CCSD Cambridge University Press (CUP)
Résumé : We tested the response of seedlings of Dicorynia guianensis, a major timber tree species of French Guiana, to mycorrhizal symbiosis and water limitation in a semi-controlled experiment under natural light conditions. Under well-watered conditions, mycorrhizal colonization resulted in an increase of net photosynthesis, growth and phosphorus uptake. When submitted to water stress, no growth reduction of mycorrhizal seedlings was observed. Mycorrhizal seedlings were more sensitive to drought than non-mycorrhizal ones in terms of carbon assimilation, but not with regard to stomatal closure. In contrast to previous studies on temperate tree seedlings, this result precludes a mycorrhizal effect on the hydraulic properties of this species. Furthermore, our results suggest that below a specific threshold of soil moisture, carbon assimilation of D. guianensis seedlings was decreased by the mycorrhizal symbiosis. This is probably related to the competition between the plant and its host fungus for carbon allocation under low light intensity, even though it did not seem to have a significant effect on mortality in our experiment.
ISSN: 0266-4674

hal-01031901
https://hal.archives-ouvertes.fr/hal-01031901
DOI : 10.1017/S0266467405002348

Éditeur(s) : HAL CCSD Wiley
Résumé : Seasonal variations in environmental conditions influence the functioning of the whole ecosystem of tropical rain forests, but as yet little is known about how such variations directly influence the leaf gas exchange and transpiration of individual canopy tree species. We examined the influence of seasonal variations in relative extractable water in the upper soil layers on predawn leaf water potential, saturated net photosynthesis, leaf dark respiration, stomatal conductance, and tree transpiration of 13 tropical rain forest canopy trees (eight species) over 2yr in French Guiana. The canopies were accessed by climbing ropes attached to the trees and to a tower. Our results indicate that a small proportion of the studied trees were unaffected by soil water depletion during seasonal dry periods, probably thanks to efficient deep root systems. The trees showing decreased tree water status (i.e., predawn leaf water potential) displayed a wide range of leaf gas exchange responses. Some trees strongly regulated photosynthesis and transpiration when relative extractable water decreased drastically. In contrast, other trees showed little variation, thus indicating good adaptation to soil drought conditions. These results have important applications to modeling approaches: indeed, precise evaluation and grouping of these response patterns are required before any tree-based functional models can efficiently describe the response of tropical rain forest ecosystems to future changes in environmental conditions.
ISSN: 0006-3606

hal-01032411
https://hal.archives-ouvertes.fr/hal-01032411
DOI : 10.1111/j.1744-7429.2012.00902.x

Éditeur(s) : HAL CCSD International Federation of Sports Medicine
Résumé : International audience
To study the exercise-induced arterial hypoxaemia (EIAH) kinetics in a world class Ironman triathlete at ventilatory threshold (TH vent), the authors simulated the cycle-run succession (CR, 20 min + 20 min) and a 20-min isolated run (R). Although 'moderate EIAH' was noted during CR, the SpO 2 kinetics of the isolated R reflected 'severe EIAH' from minutes 7 to 15 with a nadir of 85 % SpO 2 that stabilised at 90 % SpO 2 from minute 15 on. The physiological processes involved in these responses are discussed. These data indicate a systematic 'moderate EIAH' in a world class Ironman champion during CR and R at TH vent and a temporary 'severe EIAH' during R, which was attenuated when running was successive to cycling. The physiological significance of this phenomenon remains unclear, however, and further experiments are needed.
ISSN: 1528-3356

hal-01152346
https://hal.univ-antilles.fr/hal-01152346

Éditeur(s) : HAL CCSD Springer Verlag
Résumé :  
Genetic variation for intrinsic water use efficiency (W i) and related traits was estimated in a full-sib family of Quercus robur L. over 3 years. The genetic linkage map available for this F1 family was used to locate quantitative trait loci (QTL) for W i, as estimated by leaf carbon stable isotope composition (δ 13C) or the ratio of net CO2 assimilation rate (A) to stomatal conductance to water vapour (g w) and related leaf traits. Gas exchange measurements were used to standardize estimates of A and g w and to model the sensitivity of g w to leaf-to-air vapour pressure deficit (sgVPD). δ 13C varied by more than 3‰ among the siblings, which is equivalent to 40% variation of W i. Most of the studied traits exhibited high clonal mean repeatabilities (>50%; proportion of clonal mean variability in global variance). Repeatabilities for δ 13C, leaf mass per area (LMA) and leaf nitrogen content were higher than 70%. For δ 13C, ten QTLs were detected, one of which was detected repeatedly for all 3 years and consistently explained more than 20% of measured variance. Four genomic regions were found in which co-localizing traits linked variation in W i to variations in leaf chlorophyll and nitrogen content, LMA and sgVPD. A positive correlation using clonal means between δ 13C and A/g w, as well as a co-localisation of QTL detected for both traits, can be seen as validation of the theoretical model linking the genetic architecture of these two traits.
ISSN: 1614-2942

hal-01032066
https://hal.archives-ouvertes.fr/hal-01032066
DOI : 10.1007/s11295-007-0107-z

Éditeur(s) : HAL CCSD Elsevier Masson
Résumé : International audience
Alveolar proteinosis (AP) is a rare disease characterized by alveolar accumulation of surfactant components, which impairs gas exchange. AP is classified into three groups: auto-immune AP defined by the presence of plasma autoantibodies anti-GM-CSF, the most frequent form (90 % of all AP); secondary AP, mainly occurring as a consequence of haematological diseases, or following on from toxic inhalation or infections, and genetic AP, which affects almost exclusively children. AP diagnosis is suspected where chest CT-scan demonstrates interstitial lung disease with a crazy paving aspect; and confirmed by bronchoalveolar lavage, which has a milky appearance and contains periodic acid Schiff positive proteinaceous alveolar deposits. The use of surgical lung biopsy to confirm AP is less frequent nowadays. In this context, positive antibodies against GM-CSF indicates an auto-immune etiology of the AP. Concerning management, whole lung lavage is the gold standard therapy. In refractory AP, new treatments are available such as subcutaneous or inhaled GM-CSF supplementation, or rituximab infusions. The clinical course is unpredictable. Spontaneous improvement or even cure can occur, and the 5-year actuarial survival is 95 %. The most frequent complications are infectious etiology.
La protéinose alvéolaire pulmonaire (PAP) est une maladie rare caractérisée par l’accumulation alvéolaire de composants du surfactant qui gêne les échanges gazeux. Les PAP sont séparées en trois groupes : les PAP auto-immunes caractérisées par la présence d’anticorps sériques anti-GM-CSF qui sont les plus fréquentes ; les PAP secondaires à une maladie sous-jacente, le plus souvent hématologique, mais aussi à l’inhalation de toxiques et à des infections ; enfin, les PAP d’origine génétique. Le diagnostic de PAP est évoqué sur le scanner thoracique avec une pneumopathie infiltrante diffuse ayant un aspect classique de crazy paving, puis confirmé par l’aspect laiteux du lavage bronchoalvéolaire, et la présence de matériel lipoprotéinacé PAS positif. La confirmation du diagnostic de PAP par biopsie pulmonaire chirurgicale est désormais rarement nécessaire. La positivité des anticorps sériques anti-GM-CSF signe le caractère auto-immun de la maladie. Le traitement de référence des PAP auto-immunes est le « grand lavage pulmonaire thérapeutique ». En cas de maladie réfractaire, d’autres traitements sont disponibles, tels que le GM-CSF en injection sous-cutanée ou en aérosol et le rituximab. L’évolution de la maladie est imprévisible. Une évolution spontanément favorable ou même une guérison spontanée peuvent survenir et la survie actuarielle à 5 ans est de 95 %. Les principales complications sont infectieuses.
ISSN: 0761-8425

hal-01085907
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01085907
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01085907/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01085907/file/Prot%C3%A9inose%20alv%C3%A9olaire%20pulmonaire_accepted.pdf
DOI : 10.1016/j.rmr.2014.08.009

Éditeur(s) : HAL CCSD Ecological Society of America
Résumé : We investigated the relationship between habitat association and physiological performance in four congeneric species pairs exhibiting contrasting distributions between seasonally flooded and terra firme habitats in lowland tropical rain forests of French Guiana, including Virola and Iryanthera (Myristicaceae), Symphonia (Clusiaceae), and Eperua (Caesalpiniaceae). We analyzed 10-year data sets of mapped and measured saplings (stems 150 cm in height and <10 cm diameter at breast height [dbh]) and trees (stems 10 cm dbh) across 37.5 ha of permanent plots covering a 300-ha zone, within which seasonally flooded areas (where the water table never descends below 1 m) have been mapped. Additionally, we tested the response of growth, survival, and leaf functional traits of these species to drought and flood stress in a controlled experiment. We tested for habitat preference using a modification of the torus translation method. Strong contrasting associations of the species pairs of Iryanthera, Virola, and Symphonia were observed at the sapling stage, and these associations strengthened for the tree stage. Neither species of Eperua was significantly associated with flooded habitats at the sapling stage, but E. falcata was significantly and positively associated with flooded forests at the tree stage, and trees of E. grandiflora were found almost exclusively in nonflooded habitats. Differential performance provided limited explanatory support for the observed habitat associations, with only congeners of Iryanthera exhibiting divergent sapling survival and tree growth. Seedlings of species associated with flooded forest tended to have higher photosynthetic capacity than their congeners at field capacity. In addition, they tended to have the largest reductions in leaf gas exchange and growth rate in response to experimental drought stress and the least reductions in response to experimental inundation. The corroboration of habitat association with differences in functional traits and, to a lesser extent, measures of performance provides an explanation for the regional coexistence of these species pairs. We suggest that specialization to seasonally flooded habitats may explain patterns of adaptive radiation in many tropical tree genera and thereby provide a substantial contribution to regional tree diversity.
ISSN: 0012-9658

hal-01031746
https://hal.archives-ouvertes.fr/hal-01031746

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The ‘International Intercomparison Exercise of fCO₂ Systems’ was carried out in 1996 during the R/V Meteor Cruise 36/1 from Bermuda/UK to Gran Canaria/Spain. Nine groups from six countries (Australia, Denmark, France, Germany, Japan, USA) participated in this exercise, bringing together 15 participants with seven underway fugacity of carbon dioxide (fCO₂) systems, one discrete fCO₂ system, and two underway pH systems, as well as systems for discrete measurement of total alkalinity and total dissolved inorganic carbon. Here, we compare surface seawater fCO₂ measured synchronously by all participating instruments. A common infrastructure (seawater and calibration gas supply), different quality checks (performance of calibration procedures for CO2, temperature measurements) and a common procedure for calculation of final fCO₂ were provided to reduce the largest possible amount of controllable sources of error. The results show that under such conditions underway measurements of the fCO₂ in surface seawater and overlying air can be made to a high degree of agreement (±1 μatm) with a variety of possible equilibrator and system designs. Also, discrete fCO₂ measurements can be made in good agreement (±3 μatm) with underway fCO₂ data sets. However, even well-designed systems, which are operated without any obvious sign of malfunction, can show significant differences of the order of 10 μatm. Based on our results, no “best choice” for the type of the equilibrator nor specifics on its dimensions and flow rates of seawater and air can be made in regard to the achievable accuracy of the fCO₂ system. Measurements of equilibrator temperature do not seem to be made with the required accuracy resulting in significant errors in fCO₂ results. Calculation of fCO₂ from high-quality total dissolved inorganic carbon (CT) and total alkalinity (AT) measurements does not yield results comparable in accuracy and precision to fCO₂ measurements.
ISSN: 0304-4203

hal-01245605
https://hal.archives-ouvertes.fr/hal-01245605
DOI : 10.1016/S0304-4203(00)00080-3