Interobserver variability in target definition for stereotactic arrhythmia radioablation

BackgroundStereotactic arrhythmia radioablation (STAR) is a potential new therapy for patients with refractory ventricular tachycardia (VT). The arrhythmogenic substrate (target) is synthesized from clinical and electro-anatomical information. This study was designed to evaluate the baseline interobserver variability in target delineation for STAR.MethodsDelineation software designed for research purposes was used. The study was split into three phases. Firstly, electrophysiologists delineated a well-defined structure in three patients (spinal canal). Secondly, observers delineated the VT-target in three patients based on case descriptions. To evaluate baseline performance, a basic workflow approach was used, no advanced techniques were allowed. Thirdly, observers delineated three predefined segments from the 17-segment model. Interobserver variability was evaluated by assessing volumes, variation in distance to the median volume expressed by the root-mean-square of the standard deviation (RMS-SD) over the target volume, and the Dice-coefficient.ResultsTen electrophysiologists completed the study. For the first phase interobserver variability was low as indicated by low variation in distance to the median volume (RMS-SD range: 0.02–0.02 cm) and high Dice-coefficients (mean: 0.97 ± 0.01). In the second phase distance to the median volume was large (RMS-SD range: 0.52–1.02 cm) and the Dice-coefficients low (mean: 0.40 ± 0.15). In the third phase, similar results were observed (RMS-SD range: 0.51–1.55 cm, Dice-coefficient mean: 0.31 ± 0.21).ConclusionsInterobserver variability is high for manual delineation of the VT-target and ventricular segments. This evaluation of the baseline observer variation shows that there is a need for methods and tools to improve variability and allows for future comparison of interventions aiming to reduce observer variation, for STAR but possibly also for catheter ablation

Sugar and amino acid exhibit different spatial patterns of exudation in response to water stress and n nutrition in pisum sativum

Book of abstract p. 188-189, affiche et flash presentationInternational audiencePresent work focuses on the influence of root architecture and N nutrition on the interaction between plants and soil microbial communities in response to drought stress. This is especially relevant in legumes as N fixation is highly sensitive to water stress. In a context of increased intensity and frequency of drought episodes, it is important to maintain N fixation and thus legume productivity throughout the plant growth cycle. Root architecture and its plasticity can provide higher drought resilience in pea. Features such as deep rooting, nodule location and the interaction between emerging roots and microbial communities contribute to this resilience, conspicuously through N cycling in the soil (Prudent et al., 2020). Yet, little is known on the effects of root architecture on microbial communities and its consequences on soil N cycling and plant resilience. The objective of this project is to tackle this pluri-component question with a holistic approach integrating whole plant ecophysiology and microbial ecology, with spatial patterns of exudation as a cornerstone of the plant-microbiome interaction (Tixier et al., 2023).Concise description of the work (materials & methods)Pea plants were compared for their response to water stress (WS) and different sources of N nutrition (symbiotic fixation N- and nitrate fertilization N+) in terms of water relations, plant productivity, root structure (architecture, C/N) and function (growth, exudation, water and nitrogen uptake). In order to assess root architecture, the plants were grown in the RhizoTubes© of the 4PMI (Plant Phenotyping Platform for Plant and Microorganism Interaction). This innovative equipment is fairly unique for root phenotyping, allowing a quantitative non-destructive assessment of root growth and development using image analysis.Main ResultsHere we showed that water and N shortage decrease plant productivity and modulate shoot and root traits with a bigger impact of water stress on pea root structure and function than N shortage. Indeed, smaller root area was associated with smaller root growth in WS plants. WS plants root system showed a sinking architecture when compared to WW plants with significantly higher Depth/Width ratio. These structural root changes were concomitant to functional changes such as a significant decreased in specific nitrogen uptake, a significant decrease in root specific water uptake only observed in N + treatment and a significant increase of amino acids exudation in response to water stress, regardless of root location. Significant decrease of sugar exudation in response to water stress was only observed in N- plants. Further, whilesugar exudation was significantly affected by spatial position on root architecture, no significant effect of position was observed for amino acid exudation.ConclusionsThese results provide insights on the spatial regulation of exudation at the whole plant level, a first step to build a mechanistic understanding of exudation and its trade-off with productivity and resilience. Further, the correlation of these exudation patterns with microbial community structure and activity as well as soil C-N cycling will provide means to target and drive these communities in order to promote plant productivity and soil services such as C storage and N-cycling.Understanding these ecophysiological trade-offs and rhizosphere interactions is essential to develop ideotypes that are adapted to low-input agroecosystems facing climate chang

Ecophysiologie de rhizodéposition chez les legumineuses

National audienc

Diurnal pattern of primary metabolites exudation in legume sheds light on the major influence of root NSC and AA status

International audienc

Rhizode position as a functional trait in legumes. Study of trade-off for plant productivity and resilience

International audienceRhizodeposition is the release of organic carbon (C) to the soil that connects the biotic and abiotic components of the C cycle. It can promote C storage to soil but also mediates plant-microbe interactions (Jones et al., 2009). These interactions are complexes as rhizodeposition will influence the composition and functioning of microbial populations which in return are able to increase the availability of nutrients in soil and provide protection against pathogens (Sasse et al., 2018). Despite their importance for current agriculture challenges, plant-soil microbes interactions remain poorly understood due to the methodological challenge they represent and the complexity of actors and processes involved (Oburger & Jones, 2018). Indeed in the context of climate change, our current agriculture needs to reconcile with ecology and mitigate these interactions to benefit mutually environment and food production while selecting more resilient ideotypes. As plants and soil health are highly dependent on trophic and signaling interactions in the rhizosphere, it is worth noting that plants from natural ecosystems tend to exhibit more rhizodeposition than in agrosystems (Pausch & Kuzyakov, 2018). Thus, it is crucial to evaluate why crop species exhibit less rhizodeposition and what are the plant physiological processes governing rhizodeposition in terms of quantity and type (exudation, mucilage, root cap and border cells loss) at the temporal and spatial scale. Identifying potential trade-off for carbon allocation would assist the selection of resilient ideotypes and development of sustainable farming practices. Because of their potential for agroecology, we study the relationship and potential trade-off of carbon allocation in legumes with focus on the specie Pisum sativum. Carbon budget for biomass, growth, storage, nodulation and rhizodeposition at the whole plant level is performed with state of the art phenotyping and isotope labelling plateforms. We show the different rhizodeposition processes and methods to assess them in order to evaluate their respective contribution to carbon budget and microbial population management. Root mucilage is a hydrogel composed mainly of polysaccharides actively secreted by exocytosis. It provides multiple benefits such as hydraulic continuity with soil, metal complexation and rhizosphere stabilization (Kroener et al., 2016). Border cells are cells that detach from root apex. They lower frictional stress during growth but also have a major role in mediating microbial populations in legumes through the release of secondary metabolites (Watson et al., 2015). Exudates are soluble plant derived primary and secondary metabolites that can be released through active and passive mechanisms (Jones et al., 2009). Second, we present our ecophysiological structure-function approaches at the root level focusing on sugars, taking into consideration carbon and water transport. The developmental gradient of roots is studied using anatomy in order to link it to functions such as growth, storage, respiration and exudation. Further the use of hydraulic methods informs on radial and axial resistance for water flow but also passive diffusion of sugars to decipher to which extent loss of organic carbon is an unfortunate necessity for water absorption through passive loss (Zwieniecki et al., 2002)

Root exudation of carbon and nitrogen compounds varies over the day–night cycle in pea: The role of diurnal changes in internal pools

International audienceRhizodeposition is the export of organic compounds from plant roots to the soil. Carbon allocation towards rhizodeposition has to be balanced with allocation for other physiological functions, which depend on both newly assimilated and stored nonstructural carbohydrate (NSC). To test whether the exudation of primary metabolites scales with plant NSC status, we studied diurnal dynamics of NSC and amino acid (AA) pools and fluxes within the plant and the rhizosphere. These diurnal dynamics were measured in the field and under hydroponic-controlled conditions. Further, C-limiting treatments offered further insight into the regulation of rhizodeposition. The exudation of primary metabolites fluctuated diurnally. The diurnal dynamics of soluble sugars (SS) and AA concentrations in tissues coincided with exudate pool fluctuations in the rhizosphere. SS and AA pools in the rhizosphere increased with NSC and AA pools in the roots. C starvation treatments offset the balance of exudates: AA exudate content in the rhizosphere significantly decreased while SS exudate content remained stable. Our results suggest that rhizodeposition is to some extent controlled by plant C:N status. We propose that SS exudation is less controlled than AA exudation because N assimilation depends on controlled C supply while SS exudation relies to a greater extent on passive diffusion mechanism

Towards a Zero-Waste Biorefinery Using Edible Oils as Solvents for the Green Extraction of Volatile and Non-Volatile Bioactive Compounds from Rosemary

The zero-waste biorefinery concept inspired a green oleo-extraction of both natural volatile (e.g., borneol, camphor, o-cymene, eucalyptol, limonene, α-pinene, and terpinen-4-ol) and non-volatile (e.g., carnosol, carnosic, and rosmarinic acid) bioactive compounds from rosemary leaves with vegetable oils and their amphiphilic derivatives as simple food-grade solvents. It is noteworthy that soybean oil could obtain the highest total phenolic compounds (TPCs) among 12 refined oils including grapeseed, rapeseed, peanut, sunflower, olive, avocado, almond, apricot, corn, wheat germ, and hazelnut oils. Furthermore, the addition of oil derivatives to soybean oils, such as glyceryl monooleate (GMO), glyceryl monostearate (GMS), diglycerides, and soy lecithin in particular, could not only significantly enhance the oleo-extraction of non-volatile antioxidants by 66.7% approximately, but also help to remarkably improve the solvation of volatile aroma compounds (VACs) by 16% in refined soybean oils. These experimental results were in good consistency with their relative solubilities predicted by the more sophisticated COSMO-RS (COnductor like Screening MOdel for Real Solvents) simulation. This simple procedure of using vegetable oils and their derivatives as bio-based solvents for simultaneously improving the extraction yield of natural antioxidants and flavors from rosemary showed its great potential in up-scaling with the integration of green techniques (ultrasound, microwave, etc.) for zero-waste biorefinery from biomass waste to high value-added extracts in future functional food and cosmetic applications

Conciliation, réconciliation aux temps médiévaux et modernes

Depuis les travaux qui ont renouvelé les perspectives en histoire diplomatique, de nombreux chercheurs se sont intéressés à la culture de la paix, notamment à travers ses rituels. Des historiens se sont penchés sur les modes et les techniques de négociation, ainsi que sur les pratiques de conciliation ou l’idéal de réconciliation, voire de fraternité universelle. Plus récemment le domaine de l’histoire religieuse s’est ouvert à ces problématiques. Sous l’impulsion des recherches menées sur la justice, l’arbitrage et la pacification des conflits d’ordre privé sont entrés dans les champs de la recherche historique. Après s’être interrogés sur les guerres et les affrontements de religion, sur les difficultés de la tolérance, sur les manifestations de violence et d’inimitié, de nombreux chercheurs mettent désormais en avant la notion de coexistence et étudient le rôle des clercs dans différentes instances de conciliation en s’intéressant aux procédures de pacification. Le présent volume se propose de tester la pertinence de ce thème de la (ré)concilation dans le monde médiéval et moderne en faisant porter le questionnement sur l’ensemble des rapports sociaux : du politique au religieux et au culturel en passant par le judiciaire

Heart Rhythm

BACKGROUND: Differentiating between atypical atrioventricular node re-entrant tachycardia (aAVNRT) and orthodromic reciprocating tachycardia (ORT) utilizing a septal accessory pathway is a complex challenge. OBJECTIVE: We introduce the "local VA index," a straightforward method based on signals from the coronary sinus (CS) catheter, to distinguish between these arrhythmias during tachycardia and entrainment. The V-A interval on the CS catheter is measured during tachycardia and entrainment, at the site of earliest atrial activity. The difference between these two situations defines the "local VA index". Additionally, we propose a mechanism to clarify the limitations of historical pacing maneuvers, such as PPI-TCL and SA-VA, by examining nodal decrement and intraventricular conduction delay. METHODS: In a retrospective study involving 75 patients referred for supraventricular tachycardia (SVT) evaluation, 37 were diagnosed with AVRT with ORT, and 38 with AVNRT (27 typical, 11 atypical). RESULTS: In comparison to AVRT patients, AVNRT patients exhibited longer PPI-TCL (176±47ms vs. 113±42ms; p<0.01) and SA-VA (138±47ms vs. 64±28ms; p<0.01). The AVRT group had a mean local V-A index of -1 ± 13ms, while the AVNRT group had a significantly longer index of 91 ± 46ms (p<0.01). An optimal threshold for differentiation was a local VA index of 40ms. Importantly, there was no significant correlation between pacing cycle length and nodal decrement, as well as intraventricular delay related to pathway location. This interindividual variability might explain misleading interpretations of PPI-TCL and SA-VA. CONCLUSION: This novel approach is advantageous due to its simplicity and effectiveness, requiring only two diagnostic catheters. A local VA interval difference of less than 40ms provides a clear distinction for AVRT

Heart Rhythm

BACKGROUND Beyond pulmonary vein (PV) isolation, anatomic isthmus transection is an adjunctive strategy for persistent atrial fibrillation. Data on the durability of multiple lines of block remain scarce.OBJECTIVE The purpose of this study was to evaluate the impact of gaps within such a lesion set.METHODS We followed 291 consecutive patients who underwent (1) vein of Marshall ethanol infusion, (2) PV isolation, and (3) mitral, cavotricuspid, and dome isthmus transection. Dome transec-tion relied on 2 distinct strategies over time: a single roof line with touch-ups applied in case of gap demonstrated by conventional ma-neuvers (first leg), and an alternative floor line if the roof line ex-hibited a gap during high-density mapping with careful electrogram reannotation (second leg).RESULTS Twelve-month sinus rhythm maintenance was 70% after 1 procedure and 94% after 1 or 2 procedures. Event-free survival af-ter the first procedure was lower in case of residual gaps within the lesion set (log-rank, P = .004). Delayed gaps were found in 94% of a second procedure performed in the 69 patients relapsing despite a complete lesion set with PV gaps increasing the risk of recurrence of atrial fibrillation (67% vs 34%; P = .02) and anatomic isthmus gaps supporting a majority of atrial tachycardias (60%). Between the first leg and the second leg, a significant decrease was found in roof lines considered blocked during the first procedure (99% vs 78%; P , .001) and in delayed dome gaps observed during a second procedure (68% vs 43%; P = .05).CONCLUSION Gaps are arrhythmogenic and can be reduced by optimized ablation and assessment of lines of block. Closing these gaps improves sinus rhythm maintenance