Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome associated with COVID-19: An Emulated Target Trial Analysis.

RATIONALE: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. OBJECTIVES: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 <80 or PaCO2 ≥60 mmHg). We controlled for confounding using a multivariable Cox model based on predefined variables. MAIN RESULTS: 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability at Day-7 from the onset of eligibility criteria (87% vs 83%, risk difference: 4%, 95% CI 0;9%) which decreased during follow-up (survival at Day-90: 63% vs 65%, risk difference: -2%, 95% CI -10;5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand, and when initiated within the first 4 days of MV and in profoundly hypoxemic patients. CONCLUSIONS: In an emulated trial based on a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and in regions with ECMO capacities specifically organized to handle high demand. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Accumulation des metaux lourds dans Eisenia fetida andrei (Oligochaeta, Lumbricidae) eleve sur ordures menageres

On a déterminé les teneurs en Cd, Cr, Ni, Pb et Zn des vers de terreau, Eisenia fetida andrei, élevés dans un compost d’ordures ménagères âgé de 7 jours et dans un compost de référence (à base de terreau et de fèces de lapin). L’élevage a été réalisé à 25 °C, en containers de 5 kg de compost humide ensemencés avec 200 cocons pour une durée de 10 semaines. La production de biomasse lombricienne et le poids moyen des vers sont très significativement augmentés sur ordures ménagères. Seule la teneur en Pb et Zn des vers augmente quand ces derniers sont élevés dans les ordures ménagères, alors que les variations des teneurs en Cd, Cr et Ni, quand on change de milieu d’élevage, demeurent non significatives en raison d’une pollution initiale du compost de référence par ces métaux. L’élimination du contenu du tube digestif par un séjour de 24 h sur papier filtre entraîne une baisse importante des teneurs en Cr, Pb, Ni et Zn d’E. f. andrei élevé dans les ordures ménagères mais est sans action sur la teneur en Cd, métal qui doit donc être considéré comme très fortement lié au lombricien.The weight gain of a worm commonly found in manure piles (Eisenia fetida andrei) was measured after a 10 week-period of growth in fresh garbage (7 day-old) or in control compost (rabbit faeces - table 2) put in plastic boxes arranged in a growth chamber at 25 °C. The effect of the medium on Cd, Cr, Ni, Pb and Zn accumulation in worms, before or after discharge of excreta for 24 h in Petri dishes containing pieces of wet filter, was also measured. Worm biomass production and individual weights were more significantly increased in garbage than in control compost (table 3). Pb and Zn accumulated in worms growing in garbage, whereas Cd, Cr and Ni did so no more than in control compost because this latter was polluted by the metals (table 4). Discharge of faeces and excreta induced a strong decrease of Cr, Ni, Pb and Zn concentration in E. f. andrei growing in garbage but no effect of this treatment was observed for Cd, this later being strongly bound in worm tissues (table 5)

Effect of organic matter on soil inoculum potential and soil suppressiveness to <em>Gaeumannomyces graminis</em> var. <em>tritici</em> and <em>Rhizoctonia solani</em>

National audienceIt is widely recognized that organic amendments may reduce crop losses caused by soil borne plant pathogens. Most of the studies conducted so far were related to short term effects observed in vegetable cropping systems. The long term effects of compost or manure amendments in field cropping systems has been investigated in Australia and, concerning Rhizoctonia solani diseases on wheat, inconsistent results were reported. Two large field experiments were set up in 1996, at Le Rheu and la Jaillière (France), to study the effects of organic fertilization in wheat and maize production. In 2006, at the end of the experiments, soil was sampled to assess the effects of the organic matter fertilization on the soil inoculum potential and soil suppressiveness to diseases caused by Gaeumannomyces graminis var. tritici (Ggt, take all) and R. solani. Bioassays were set up in growth chamber, using wheat and carrots to measure soil inoculum potential and soil suppressiveness to Ggt and R. solani, respectively. A pathological index was used to evaluate the disease severity caused by Ggt on wheat and area under the disease progress curve (AUDPC) was calculated to quantify the disease severity caused by R. solani. ANOVA was used to compare the data. At both locations, the inoculum potential of the soils naturally infested by Ggt was low and similar in plots amended with different organic matters and mineral fertilization. The level of soil suppressiveness to take-all was high in plots amended with organic matter compared to the low level after mineral fertilisation. This suggests that organic amendments preserved the suppressive ability of the soil towards take all when a wheat/maize rotation is performed. Concerning R. solani, the soil inoculum potential was reduced in plots amended with organic matters, but only at La Jaillière not at Le Rheu. At both 2 locations, soil suppressiveness to R. solani damping-off was not affected by organic amendments. There were neither clear positive nor detrimental effects of organic fertilisation in a wheat/maize rotation. Therefore organic matter can be used to improve soil fertility without any negative effects on the phytosanitary status of soil

Effect of organic matter on soil inoculum potential and soil suppressiveness to Gaeumannomyces graminis var. tritici and Rhizoctonia solani

It is widely recognized that organic amendments may reduce crop losses caused by soil borne plant pathogens. Most of the studies conducted so far were related to short term effects observed in vegetable cropping systems. The long term effects of compost or manure amendments in field cropping systems has been investigated in Australia and, concerning Rhizoctonia solani diseases on wheat, inconsistent results were reported. Two large field experiments were set up in 1996, at Le Rheu and la Jaillière (France), to study the effects of organic fertilization in wheat and maize production. In 2006, at the end of the experiments, soil was sampled to assess the effects of the organic matter fertilization on the soil inoculum potential and soil suppressiveness to diseases caused by Gaeumannomyces graminis var. tritici (Ggt, take all) and R. solani. Bioassays were set up in growth chamber, using wheat and carrots to measure soil inoculum potential and soil suppressiveness to Ggt and R. solani, respectively. A pathological index was used to evaluate the disease severity caused by Ggt on wheat and area under the disease progress curve (AUDPC) was calculated to quantify the disease severity caused by R. solani. ANOVA was used to compare the data. At both locations, the inoculum potential of the soils naturally infested by Ggt was low and similar in plots amended with different organic matters and mineral fertilization. The level of soil suppressiveness to take-all was high in plots amended with organic matter compared to the low level after mineral fertilisation. This suggests that organic amendments preserved the suppressive ability of the soil towards take all when a wheat/maize rotation is performed. Concerning R. solani, the soil inoculum potential was reduced in plots amended with organic matters, but only at La Jaillière not at Le Rheu. At both 2 locations, soil suppressiveness to R. solani damping-off was not affected by organic amendments. There were neither clear positive nor detrimental effects of organic fertilisation in a wheat/maize rotation. Therefore organic matter can be used to improve soil fertility without any negative effects on the phytosanitary status of soil

Response of <em>Rhizoctonia solani</em> to soil faunal grazing and organic amendments – different from general microbial dynamics

National audienceIn a four-month microcosm experiment, we studied the effect of enchytraeids and earthworms on dynamics of Rhizoctonia solani in soil amended with different types of organic material. Special focus was on comparing the effects with those on total microbial densities, to see if the development of the pathogen follows the general dynamics of saprophytic bacteria and fungi in the system. We found that animal effects on the density of R. solani and on the densities of culturable fungi and bacteria were dependent not only on type of animal present, but also on the amount and type of organic material available. The highest densities of bacteria and fungi were found in soil amended with fresh organic material in presence of earthworms and the lowest densities in non-amended soil with enchytraeids. While the bacteria and fungi responded similarly to animal and organic material treatments, the response of R. solani showed an opposite pattern with the highest densities observed in the treatments with the lowest densities of fungi and bacteria. These results show that R. solani does not follow the general dynamics of soil microorganisms. As the highest densities of R. solani were found in treatments with a high grazing pressure, our findings also indicate that R. solani may get a competitive advantage from soil faunal grazing

Ecological role of mycotoxin and consequences of the presence of mycotoxins in crop residues on the survival and pathogenic activity of Fusarium graminearum

National audienc

Impact of deoxynivalenol on soil microflora and fauna

National audienceF. graminearum is an important pathogen that causes head blight of cereal crops as wheat and maize. It also produces the mycotoxins (as Deoxynivalenol=DON) which are toxic to the human and animals. During the off season the pathogen survives in the soil, on weeds and in crop residues. A 24 weeks study was conducted in controlled conditions (microcosms of natural soil, 17 °C, 80% WHC) to test whether the presence of DON in the wheat crop residues gives competitive advantage to F. graminearum over the other soil microflora and fauna to survive and develop a primary inoculum during the decomposition process. This study was carried out in the presence of the whole soil biota (i.e. fungi, bacteria, protozoa, nematodes and earthworms). In this experimental approach, wheat straw was inoculated with F. graminearum. The latter was placed on the soil surface or incorporated into the natural soil. This experiment was conducted with (1mg DON/kg soil-straw mixture) and without DON. The molecular biomass of fungi, bacteria and F. graminearum was determined by qPCR (real time polymerase chain reaction). The changes in the community structure of fungi, bacteria, protozoa and nematodes were determined by T-RFLP (terminal restriction fragment length polymorphism). The results suggested that DON in wheat straw showed an impact on part of the biotic components of the soil but the impact depended on the communities and on the location of the wheat residues

Response of Rhizoctonia solani to soil faunal grazing and organic amendments – different from general microbial dynamics

In a four-month microcosm experiment, we studied the effect of enchytraeids and earthworms on dynamics of Rhizoctonia solani in soil amended with different types of organic material. Special focus was on comparing the effects with those on total microbial densities, to see if the development of the pathogen follows the general dynamics of saprophytic bacteria and fungi in the system. We found that animal effects on the density of R. solani and on the densities of culturable fungi and bacteria were dependent not only on type of animal present, but also on the amount and type of organic material available. The highest densities of bacteria and fungi were found in soil amended with fresh organic material in presence of earthworms and the lowest densities in non-amended soil with enchytraeids. While the bacteria and fungi responded similarly to animal and organic material treatments, the response of R. solani showed an opposite pattern with the highest densities observed in the treatments with the lowest densities of fungi and bacteria. These results show that R. solani does not follow the general dynamics of soil microorganisms. As the highest densities of R. solani were found in treatments with a high grazing pressure, our findings also indicate that R. solani may get a competitive advantage from soil faunal grazing

Ecological role of mycotoxins in wheat crop residues and consequences on the multitrophic interactions in the soil and further development of Fusarium graminearum

Affiche, résuméFusarium graminearum causes wheat head blight disease and produce differentmycotoxins (as Deoxynivalenol=DON) which are toxic for human and animal. During off season itsurvives in the soil, on weeds and in crop residues. A 6 months study was conducted in controlledconditions (microcosms of natural soil, 17°C, 80%WHC) to test whether the presence of DON inthe wheat crop residues gives advantages to F. graminearum to survive and develop a primaryinoculum during the decomposition process. This study was carried out in the presence of the wholesoil biota (i.e. fungi, bacteria, protozoa, nematodes and earthworms). Both F. graminearum and thebiota were monitored during the decomposition process. The wheat crop residues were placed onthe soil surface or incorporated into the natural soil. This experiment was conducted with (1mgDON/kg soil-straw mixture) and without DON. This study suggested that the mycotoxins provideda competitive advantage to F. graminearum and were deleterious towards the fungal communityand the nematodes but not towards the bacteria or the earthworms. However, all the results were notstatistically significant. The use of molecular tools as well as the forthcoming quantification ofDON in the residues during 24 weeks of observation will provide the clarification and may confirmor not the trends we observed

Cause and duration of mustard incorporation effects on soil-borne plant pathogenic fungi

International audienceTwo fungal plant pathogens, Rhizoctonia solani AG 2-2 and Fusarium oxysporum f.sp. lini, were studied in relation to general responses of soil fungi and bacteria following incorporation of Brassica juncea. Our aim was to understand to what extent the changes in the biological and physicochemical characteristics of the soil could explain the effects on the studied pathogens and diseases, and to determine the temporal nature of the responses. Short-term effects of mustard incorporation (up to 4 months) were investigated in a microcosm experiment, and compared with a treatment where composted plant material was incorporated. In a field experiment, the responses were followed up to 11 months after removal or incorporation of a mustard crop. In general, responses in the variables measured changed more after incorporation of fresh mustard material than after addition of similar amounts of composted plant material (microcosms) or after removal of the mustard crop (field). The soil inoculum potential of R. solani AG 2-2 decreased directly after incorporation of mustard, but increased later to disease levels above those in the untreated soil. Neither of these effects could be explained by changes in the population density of R. solani AG 2-2. Fusarium spp. were less influenced, although an increase in the suppressiveness to Fusarium wilt was observed after mustard incorporation as compared with the treatment where mustard was removed. The microbial responses to mustard incorporation were more pronounced for bacteria than for fungi. After an initial substantial increase, the bacterial density decreased but remained above the levels in the control treatment throughout the experimental periods. The bacterial community structure was modified up to 8 months after mustard incorporation. We conclude that incorporation of fresh mustard influences soil microbial communities, especially the bacteria, and has a potential to control the pathogenic activity of R. solani 2-2 on a short-term perspective. The time dependency in microbial responses is important and should be taken into consideration for the evaluation of the potential of Brassicas to control plant disease on a field scale