Water quality assessment by means of HFNI valvometry and high-frequency data modeling

International audienceThe high-frequency measurements of valve activity in bivalves (e.g., valvometry) over a long period of time and in various environmental conditions allow a very accurate study of their behaviors as well as a global analysis of possible perturbations due to the environment. Valvom- etry uses the bivalve's ability to close its shell when exposed to a contaminant or other abnormal environmental conditions as an alarm to indicate possible perturbations in the environment. The modeling of such high-frequency serial valvom- etry data is statistically challenging, and here, a nonparametric approach based on kernel estima- tion is proposed. This method has the advantage of summarizing complex data into a simple den- sity profile obtained from each animal at every 24-h period to ultimately make inference about time effect and external conditions on this profile. The statistical properties of the estimator are pre- sented. Through an application to a sample of 16 oysters living in the Bay of Arcachon (France), we demonstrate that this method can be used to first estimate the normal biological rhythms of permanently immersed oysters and second to de- tect perturbations of these rhythms due to changes in their environment. We anticipate that this ap- proach could have an important contribution to the survey of aquatic systems

In the darkness of the polar night, scallops keep on a steady rhythm

Published version. Source at http://doi.org/10.1038/srep32435. License CC BY 4.0.Although the prevailing paradigm has held that the polar night is a period of biological quiescence, recent studies have detected noticeable activity levels in marine organisms. In this study, we investigated the circadian rhythm of the scallop Chlamys islandica by continuously recording the animal’s behaviour over 3 years in the Arctic (Svalbard). Our results showed that a circadian rhythm persists throughout the polar night and lasts for at least 4 months. Based on observations across three polar nights, we showed that the robustness and synchronicity of the rhythm depends on the angle of the sun below the horizon. The weakest rhythm occurred at the onset of the polar night during the nautical twilight. Surprisingly, the circadian behaviour began to recover during the darkest part of the polar night. Because active rhythms optimize the fitness of an organism, our study brings out that the scallops C. islandica remain active even during the polar night

Monitoring biological rhythms through the dynamic model identification of an oyster population

International audienceThe measurements of valve activity in a population of bivalves under natural environmental conditions (16 oysters in the Bay of Arcachon, France) are used for a physiological model identification. A nonlinear auto-regressive exogenous (NARX) model is designed and tested. The method to design the model has two parts. 1) Structure of the model: The model takes into account the influence of environmental conditions using measurements of the sunlight intensity, the moonlight, tide levels, precipitation and water salinity levels. A possible influence of the internal circadian/circatidal clocks is also analyzed. 2) Least square calculation of the model parameters. Through this study, it is demonstrated that the developed dynamical model of the oyster valve movement can be used for estimating normal physiological rhythms of permanently immersed oysters and can be considered for detecting perturbations of these rhythms due to changes in the water quality, i.e. for ecological monitoring

Increased mean aliphatic lipid chain length in left ventricular hypertrophy secondary to arterial hypertension: A cross-sectional study

About 77.9 million (1 in 4) American adults have high blood pressure. High blood pressure is the primary cause of left ventricular hypertrophy (LVH), which represents a strong predictor of future heart failure and cardiovascular mortality. Previous studies have shown an altered metabolic profile in hypertensive patients with LVH. The goal of this study was to identify blood metabolomic LVH biomarkers by H NMR to provide novel diagnostic tools for rapid LVH detection in populations of hypertensive individuals. This cross-sectional study included 48 hypertensive patients with LVH matched with 48 hypertensive patients with normal LV size, and 24 healthy controls. Two-dimensional targeted M-mode echocardiography was performed to measure left ventricular mass index. Partial least squares discriminant analysis was used for the multivariate analysis of the H NMR spectral data. From the H NMR-based metabolomic profiling, signals coming from methylene (-CH2-) and methyl (-CH3) moieties of aliphatic chains from plasma lipids were identified as discriminant variables. The -CH2-/-CH3 ratio, an indicator of the mean length of the aliphatic lipid chains, was significantly higher (P < 0.001) in the LVH group than in the hypertensive group without LVH and controls. Receiver operating characteristic curve showed that a cutoff of 2.34 provided a 52.08% sensitivity and 85.42% specificity for discriminating LVH (AUC = 0.703, P-value < 0.001). We propose the -CH2-/-CH3 ratio from plasma aliphatic lipid chains as a biomarker for the diagnosis of left ventricular remodeling in hypertension

Blood Signature of Pre-Heart Failure: A Microarrays Study

International audienceBACKGROUND: The preclinical stage of systolic heart failure (HF), known as asymptomatic left ventricular dysfunction (ALVD), is diagnosed only by echocardiography, frequent in the general population and leads to a high risk of developing severe HF. Large scale screening for ALVD is a difficult task and represents a major unmet clinical challenge that requires the determination of ALVD biomarkers. METHODOLOGY/PRINCIPAL FINDINGS: 294 individuals were screened by echocardiography. We identified 9 ALVD cases out of 128 subjects with cardiovascular risk factors. White blood cell gene expression profiling was performed using pangenomic microarrays. Data were analyzed using principal component analysis (PCA) and Significant Analysis of Microarrays (SAM). To build an ALVD classifier model, we used the nearest centroid classification method (NCCM) with the ClaNC software package. Classification performance was determined using the leave-one-out cross-validation method. Blood transcriptome analysis provided a specific molecular signature for ALVD which defined a model based on 7 genes capable of discriminating ALVD cases. Analysis of an ALVD patients validation group demonstrated that these genes are accurate diagnostic predictors for ALVD with 87% accuracy and 100% precision. Furthermore, Receiver Operating Characteristic curves of expression levels confirmed that 6 out of 7 genes discriminate for left ventricular dysfunction classification. CONCLUSIONS/SIGNIFICANCE: These targets could serve to enhance the ability to efficiently detect ALVD by general care practitioners to facilitate preemptive initiation of medical treatment preventing the development of HF

Index de performance myocardique (analyse des corrélations entre le mode doppler pulsé et le mode doppler tissulaire)

Objectifs : apprécier le degré de corrélation entre le MPI mesuré par la méthode conventionnelle et le MPI mesuré en Doppler tissulaire à l'anneau mitral et tricuspide. Méthode : Nous avons inclus 37 patients indemnes de cardiopathie documentée. Les mesures d'intervalles systoliques et diastoliques ont été réalisées successivement en Doppler pulsé et en Doppler tissulaire aux quatre sites de l'anneau mitral et au site latéral de l'anneau tricuspide. Le MPI était calculé en divisant la somme des temps de contraction et de relaxation isovolumiques par le temps d'éjection à chaque site. Résultats : La corrélation entre les deux méthodes est modérée pour le ventricule gauche et mauvaise pour le ventricule droit. Ces différences sont essentiellement attribuées à un allongement des temps isovolumiques en Doppler tissulaire. Il n'y avait pas d'impact de l'hypertension artérielle. Conclusion : L'index de Tei en Doppler tissulaire apparaît donc comme un paramètre différent et non une alternative à l'index classique. Il semble être un index de performance pariétale et segmentaire plus dépendant des anomalies structurelles du myocarde. Il pourrait donc permettre d'affiner les données de l'index de Tei traditionnel dans certaines pathologies cardiaques.TOULOUSE3-BU Santé-Centrale (315552105) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Morphologie et fonctions de l'oreillette gauche dans l'insuffisance cardiaque en rythme sinusal

L'échographie cardiaque est l'examen de choix pour le diagnostic et le suivi des patients insuffisants cardiaques. Nous avons étudié 107 patients porteurs d'une cardiomyopathie dilatée en rythme sinusal par échographie transthoracique et œsophagienne. Le but était de mieux étudier les fonctions atriales et la présence de contraste spontané. Le contraste spontané était présent dans 71% des cas. Il existait une forte association entre le contraste spontané et l'anatomie (p<0,0001) et les fonctions atriales (p<0,0001). De plus, nous retrouvions une importante corrélation entre le profil diastolique et le contraste spontané (p<0,0001). La fonction contractile atriale était assimilable à la fonction contractile auriculaire (p<0,0001). Deux marqueurs indépendants de la présence de contraste spontané ont pu être mis en évidence : la vitesse de vidange auriculaire (p= 0,037) et le temps de déccelération (p=0,001). Le contraste spontané considéré comme état préthrombotique, est lui-même un marqueur majeur du risque thromboembolique de l'insuffisance cardiaque. Le risque thromboembolique des cardiomyopathies dilatées n'est pas négligeable. Le traitement anticoagulant au long cours des patients insuffisants cardiaques est bénéfique en terme de survie. Ces éléments devraient être pris en compte lors de la discussion de la mise sous anticoagulant des patients porteurs d'une cardiomyopathie dilatéeTOULOUSE3-BU Santé-Centrale (315552105) / SudocTOULOUSE3-BU Santé-Allées (315552109) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

New improvments in biomonitoring and risk assessment by mollusk valve opening analysis

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In situ giant clam growth rate behavior in relation to temperature : a one-year coupled study of high-frequency noninvasive valvometry and sclerochronology

International audienceThe life history of 15 giant clams, Hippopus hippopus, was studied in situ in the southern lagoon of New Caledonia; growth rate and animal behavior were studied both by sclerochronology and high-frequency noninvasive (HFNI) valvometry. Electrodes glued on each valve of each specimen recorded the shell-gaping behavior at 0.6-Hz frequency. A nonparametric regression model was used to model clam behavior. The daily increment thickness in the inner layer of five representative clams was measured. H. hippopus has its valves open during the day and partly closed during the night all year round, and shell growth is continuous. The cumulative growth using both techniques was similar, as was the mean daily thickness increment. The occurrence of one increment per day in H. hippopus shell was measured by valvometry. The five sclerochronological profiles were highly similar. Shell growth was significantly correlated to rising sea surface temperature (SST), up to 27 degrees C. At the solar maximum, gaping behavior and increment thickness became erratic. SST- and solar irradiance-related stress could be related to physiological oxidative stress triggered by zooxanthellae symbionts. In the present context of globally increasing SST, our data indicate that the giant clams H. hippopus could live beyond their thermal comfort limits in summer in New Caledonia

Non parametric regression estimator: application in valvometry

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