Quantifying the PR interval pattern during dynamic exercise and recovery.

International audienceWe present a novel analysis tool for time delay estimation in electrocardiographic signal processing. This tool enhances PR interval estimation (index of the atrioventricular conduction time) by limiting the distortion effect of the T wave overlapping the P wave at high heart rates. Our approach consists of modeling the T wave, cancelling its influence, and finally estimating the PR intervals during exercise and recovery with the proposed generalized Woody method. Different models of the T wave are presented and compared in a statistical summary that quantitatively justifies the improvements introduced by this study. Among the different models tested, we found that a piecewise linear function significantly reduces the T wave-induced bias in the estimation process. Combining this modeling with the proposed time delay estimation method leads to accurate PR interval estimation. Using this method on real ECGs recorded during exercise and its recovery, we found: 1) that the slopes of PR interval series in the early recovery phase are dependent on the subjects' training status (average of the slopes for sedentary men = 0.11 ms/s, and for athlete men = 0.28 ms/s), and 2) an hysteresis phenomenon exists in the relation PR/RR intervals when data from exercise and recovery are compared

ARIA digital anamorphosis : Digital transformation of health and care in airway diseases from research to practice

Digital anamorphosis is used to define a distorted image of health and care that may be viewed correctly using digital tools and strategies. MASK digital anamorphosis represents the process used by MASK to develop the digital transformation of health and care in rhinitis. It strengthens the ARIA change management strategy in the prevention and management of airway disease. The MASK strategy is based on validated digital tools. Using the MASK digital tool and the CARAT online enhanced clinical framework, solutions for practical steps of digital enhancement of care are proposed.Peer reviewe

Time-frequency analysis of heart rate variability reveals cardiolocomotor coupling during dynamic cycling exercise in humans.

International audienceTo test the hypothesis that cycling exercise modulates heart rate variability (HRV), we applied a short-time Fourier transform on the electrocardiogram of subjects performing a maximal graded cycling test. A pedaling frequency component (PFC) in HRV was continuously observed over the time course of the exercise test and extracted from R-R interval series obtained from 15 healthy subjects with a heterogeneous physical fitness, exercising at three different pedaling frequency (n = 5): 70, 80, and 90 rpm. From 30 to 50% of the maximal power output (P(max)), in the 90 rpm group, spectral aliasing caused PFC to overlap with the respiratory sinus arrhythmia (RSA) band, significantly overestimating the PFC amplitude (A(PFC)). In the meantime, A(PFC) did not increase significantly from its minimal values in the 70 rpm ( approximately 1.26 ms) and 80 rpm ( approximately 1.20 ms) groups. Then, from 60 to 100% maximal power output (P(max)), workload increase caused a significant approximately 2.8-, approximately 3.3-, and approximately 3.4-fold increase in A(PFC) in the 70, 80, and 90 rpm groups, respectively, with no significant difference between groups. At peak exercise, A(PFC) accounted for approximately 43, approximately 39, and approximately 49% of the total HRV in the 70, 80, and 90 rpm groups, respectively. Our findings indicate that cycling continuously modulates the cardiac chronotropic response to exercise, inducing a new component in HRV, and that workload increase during intense exercise further accentuates this cardiolocomotor coupling. Moreover, because PFC and RSA overlapped at low workloads, methodological care should be taken in future studies aiming to quantify RSA as an index of parasympathetic activity

Efficient gene targeting and foreign DNA removal by homologous recombination in the picoeukaryote Ostreococcus

With fewer than 8000 genes and a minimalist cellular organization, the green picoalga Ostreococcus tauri is one of the simplest photosynthetic eukaryotes. Ostreococcus tauri contains many plant-specific genes but exhibits a very low gene redundancy. The haploid genome is extremely dense with few repeated sequences and rare transposons. Thanks to the implementation of genetic transformation and vectors for inducible overexpression/knockdown this picoeukaryotic alga has emerged in recent years as a model organism for functional genomics analyses and systems biology. Here we report the development of an efficient gene targeting technique which we use to knock out the nitrate reductase and ferritin genes and to knock in a luciferase reporter in frame to the ferritin native protein. Furthermore, we show that the frequency of insertion by homologous recombination is greatly enhanced when the transgene is designed to replace an existing genomic insertion. We propose that a natural mechanism based on homologous recombination may operate to remove inserted DNA sequences from the genome

Validation of the IPFM model for the Heart Rate Variability analysis

International audienc

Analysis of the respiratory and cardiac systems coupling in pyramidal exercise using a time-varying model

International audienc

Influence of Ventilation on Respiratory Sinus Arrhythmia (RSA) during Exercise

International audienc

Assessing dynamic changes in respiratory and cardiac systems coupling in non-stationary exercise

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A method for the use of the radiotracer 55Fe for microautoradiography and CARD-FISH of natural bacterial communities

Heterotrophic bacteria are key players in the biogeochemical cycle of iron (Fe) in the ocean, but the capability of different bacterial groups to access this micronutrient is ignored thus far. The aim of our study was to develop a protocol for the combined application of microautoradiography (MICRO) and catalyzed reporter depositionfluorescence in situ hybridization (CARD-FISH) using the radioisotope 55Fe. Among the different washing solutions tested, Ti-citrate-EDTA was the most efficient for the removal of extracellular 55Fe providing sufficiently low background values. We further demonstrate that the washing of cells with Ti-citrate-EDTA and the fixation with paraformaldehyde or formaldehyde do not induce leakage of intracellular 55Fe. Incubating natural bacterial communities collected from contrasting environments, the NW Mediterranean Sea and the Southern Ocean, with 55Fe revealed that 329% of bacterial cells were associated with silver grains. Combining microautoradiography with CARD-FISH, we demonstrate that the contribution of different bacterial groups to total 55Fe-incorporating cells was overall reflected by their relative contribution to abundance. An exception to this pattern was the proportionally higher contribution of Gammaproteobacteria, SAR86 and Alteromonas. Our study demonstrates the feasibility of MICRO-CARD-FISH using the radiotracer 55Fe and provides the first description of marine bacterial assemblages actively incorporating Fe

Hysteresis Analysis of the PR-PP Relation under Exercise Conditions

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