Approche à l'échelle du système racinaire de l'absorption hydro-minérale. Conséquences en matière de modélisation

Le but du travail que nous présentons est de discuter de la fonction d'absorption hydro-minérale considérée à l'échelle du système racinaire. L'approche la plus souvent utilisée consiste à attribuer à chaque élément de racine d'un système racinaire la même efficacité vis-à-vis de l'absorption pour estimer ensuite l'absorption totale par l'ensemble du système. Cette hypothèse est souvent considérée comme extrêmement simplificatrice. L'objectif principal de cette revue est de la confronter aux données actuelles de la littérature. Dans un premier temps, nous présentons divers travaux qui permettent de juger du bien fondé de cette approche au niveau du système racinaire. En particulier, nous présentons des données sur la variabilité de l'absorption racinaire considérée à différents niveaux : le long d'une racine, entre racines, en conditions de disponibilité hydrique ou minérale hétérogène, et dans le temps. Cette analyse permet de montrer qu'un tel niveau d'intégration paraît fondé pour aborder l'absorption racinaire de l'eau et du nitrate. Pour les autres éléments majeurs de la nutrition minérale, le problème est à raisonner au cas par cas en fonction des conditions particulières d'alimentation. Dans un second temps, après une rapide présentation des formalismes des modèles d'absorption, nous envisageons les conséquences de l'analyse précédente en matière de modélisation macroscopique de l'absorption racinaire. Pour l'absorption d'eau, nous soulignons que la prise en compte du potentiel hydrique et de la conductance hydraulique des racines devrait constituer un progrès dans les futurs travaux de modélisation dans ce domaine. Pour l'absorption minérale, l'état des connaissances apparaît comme moins développé, par exemple le concept même de besoins minéraux reste encore mal défini, et les progrès possibles semblent moins immédiats. Différentes voies sont cependant indiquées dans le but d'améliorer les modèles actuels.Water and mineral uptake by the root system of plants, with special regard to modelling absorption by the roots. The review deals with the water and mineral uptake by the root system of plants. The validity of the root system approach is studied based on the concept of a root demand coefficient. The variability of net influx rates is considered in a single root and between roots, according to the variability in water and nutrient availability, and according to time. It appears that the root system approach is well adaptated to the study of water and nitrate uptake by plants. As regards other major nutrients, the particular experimental conditions have to be taken into consideration. Some consequences of these mechanisms are presented in terms of modelling water and mineral uptake by roots. Regarding water absorption, it is concluded that including plant parameters such as root water potential and hydraulic conductivity may improve water uptake modelling. As regards mineral absorption modelling, it should be noted that further research still has to be carred out, eg the concept of plant mineral requirements has not yet been fully defined. Thus the improvement of mineral uptake models appears to be more complex. Nevertheless, some ways to improve mineral uptake models have been presented in this review

Antibiothérapie des endocardites infectieuses en 2021: actualités

National audience[No abstract available

A pilot project of expert nurses for the follow-up of complex intravenous antimicrobial treatment

International audienceOBJECTIVE: To report a pilot project of expert nurses for outpatient parenteral antimicrobial treatment (OPAT) follow-up. METHODS: Three nurses with specific training on antibiotics started a state-funded programme including: i) consultations for OPAT follow-up; ii) hotline for satellite hospitals; iii) peer training. Patients’ data were prospectively collected. A representative sample of patients and physicians was interviewed to learn about their opinion on the project. RESULTS: From December 2020 to December 2021, 118 patients (median age 66.5 years [52-75], male-to-female ratio 2.5) were enrolled, for a total of 621 consultations. Patients were mostly on OPAT for bone and joint infections (n = 76, 64 %) and cardiovascular infections (n = 16, 14 %), for a median duration of 29 days [22-57]. Eleven patients (9 %) required unplanned hospital admissions, and three experienced treatment failure. Most patients (21/22) and physicians in charge (10/10) reported a high level of satisfaction. CONCLUSIONS: Nurses may be important actors for OPAT follow-up

Non-HACEK gram-negative bacilli endocarditis: a multicentre retrospective case-control study

International audienceBACKGROUND: Infective endocarditis (IE) caused by non-HACEK gram-negative bacilli (GNB) is poorly characterised and may be emerging as a consequence of medical progress. METHODS: We performed an observational retrospective case-control study. Cases were non-HACEK GNB IE, definite or possible (modified Duke criteria), diagnosed in adults between 2007 and 2020 in six French referral hospitals. Two controls were included for each case (IE due to other bacteria, matched by sites and diagnosis date). RESULTS: Non-HACEK GNB were identified in 2.4% (77/3230) of all IE during the study period, with a mean age of 69.2 ± 14.6 years, and a large male predominance (53/77, 69%). Primary pathogens were Escherichia coli (n = 33), Klebsiella sp. (n = 12) and Serratia marcescens (n = 9), including eight (10%) multidrug-resistant GNB. Compared to controls (n = 154: 43% Streptococcus sp., 41% Staphylococcus sp. and 12% Enterococcus sp.), non-HACEK GNB IE were independently associated with intravenous drug use (IVDU, 8% vs. 2%, p = .003), active neoplasia (15% vs. 6%, p = .009), haemodialysis (9% vs. 3%, p = .007) and healthcare-associated IE (36% vs. 18%, p = .002). Urinary tract was the main source of infection (n = 25, 33%) and recent invasive procedures were reported in 29% of cases. Non-HACEK GNB IE were at lower risk of embolism (31% vs. 47%, p = .002). One-year mortality was high (n = 28, 36%). Comorbidities, particularly malignant hemopathy and cirrhosis, were associated with increased risk of death. CONCLUSIONS: Non-HACEK GNB are rarely responsible for IE, mostly as healthcare-associated IE in patients with complex comorbidities (end-stage renal disease, neoplasia), or in IVDUs

The Price of Coviability: Pollination at All Costs. Legal Approach to the New Relationship Between Man and Pollinators

International audienc

Chronic use of inhaled corticosteroids in patients admitted for respiratory virus infections: a 6-year prospective multicenter study

International audienceInhaled corticosteroids (ICS) have been associated with increased risk of pneumonia. Their impact on respiratory virus infections is unclear. We performed a post-hoc analysis of the FLUVAC cohort, a multicenter prospective cohort study of adults hospitalized with influenza-like illness (ILI) during six consecutive influenza seasons (2012–2018). All patients were tested for respiratory virus infection by multiplex PCR on nasopharyngeal swabs and/or bronchoalveolar lavage. Risk factors were identified by logistic regression analysis. Among the 2658 patients included, 537 (20.2%) were treated with ICS before admission, of whom 282 (52.5%, 282/537) tested positive for at least one respiratory virus. Patients on ICS were more likely to test positive for non-influenza respiratory viruses (25.1% vs. 19.5%, P = 0.004), especially for adenovirus (aOR 2.36, 95% CI 1.18–4.58), and respiratory syncytial virus (aOR 2.08, 95% CI 1.39–3.09). Complications were reported in 55.9% of patients on ICS (300/537), primarily pneumonia (171/535, 32%). Among patients on chronic ICS who tested positive for respiratory virus, 14.2% (40/282) were admitted to intensive care unit, and in-hospital mortality rate was 2.8% (8/282). Chronic use of ICS is associated with an increased risk of adenovirus or RSV infections in patients admitted for ILI