Contribution des isoformes de la myosine à l'obstruction respiratoire dans le souffle chez le cheval

La myosine est une protéine motrice impliquée dans la contraction du muscle lisse. Un de ces isoformes, appelé (+)insert lui procure une vélocité accrue. L’objectif de cette étude était d’évaluer la contribution de cet isoforme au bronchospasme observé chez les chevaux atteints de souffle, un modèle d’asthme humain. Nous avons procédé à l’analyse de l’expression génique de l’isoforme (+)insert dans les voies respiratoires de chevaux issus de 3 cohortes afin d’évaluer 1) la présence de cet isoforme chez les chevaux atteints de souffle ; 2) la réversibilité de son expression avec 2 traitements usuels (corticostéroïdes inhalés et retrait antigénique); et 3) la cinétique de réapparition de l’isoforme suite à une période de rémission de la maladie. Les résultats révèlent 1) une expression augmentée de l’isoforme (+)insert dans l’ensemble de l’arbre bronchique des chevaux atteints de souffle en exacerbation comparée aux contrôles et aux chevaux en rémission ; 2) les deux traitements conduisent à une réduction de l’expression de l’isoforme, mais l’administration de corticostéroïdes mène à une diminution plus rapide que celle induite par le retrait antigénique; et 3) une période de 30 jours ou plus d'exposition antigénique est nécessaire pour la réapparition de l’isoforme (+)insert dans l’arbre bronchique des chevaux atteints de souffle. Cette étude montre pour la première fois une modulation et une réversibilité de l’expression de l'isoforme (+)insert de la myosine en fonction du statut médical du sujet. Les données suggèrent que cet isoforme pourrait faire partie d’un mécanisme protecteur activé en réponse à une exposition antigénique prolongée.Myosin is a motor protein implicated in smooth muscle contraction. The (+)insert isoform doubles smooth muscle velocity. The aim of the study was to evaluate the contribution of the fast contracting myosin isoform to bronchospasm in heaves-affected horses as model of human asthma. Gene expression analysis of the (+)insert myosin isoform in equine airways was performed in three different cohorts to evaluate 1) its presence and anatomical location in heaves-affected horses; 2) the reversibility of its expression with two common therapies (inhaled corticosteroids and antigen avoidance); and 3) its kinetics of reappearance following a chronic antigen exposure. Results showed 1) a significantly increased expression of the (+)insert isoform at all levels of the bronchial tree of horses with heaves in clinical exacerbation when compared to control horses and heaves-affected horses in clinical remission; 2) both treatments reduced the fast isoform expression in horses’ lower airways, but the administration of corticosteroids led to a faster response; and 3) (+)insert isoform does not increase in airways of all horses with heaves within 30 days of antigen exposure. The study shows for the first time a modulation of the fast contracting myosin isoform with the disease status. Data also suggest that (+)insert isoform is part of a protective mechanism enhanced in response to a prolonged antigen exposure

Impact of two root systems, earthworms and mycorrhizae on the physical properties of an unstable silt loam Luvisol and plant production

Background and aims: Soil organisms are known to engineer the soil physical properties, but their impact is difficult to assess and poorly documented. Shrinkage analysis has a good potential for such assessment. This study analyses the effects of mycorrhizae (Glomus intraradices), earthworms (Allolobophora chlorotica) and two plants, Allium porrum (leek) and Petunia hybrida (petunia), on the physical properties of an unstable loamy Luvisol, as well as the biological interactions between the soil organisms. Methods: In addition to soil organism biomass, shrinkage analysis and soil aggregate stability analysis were used to characterize the soil physical properties. Results: The soil aggregate stability, specific volume and structural pores volumes were increased with plant roots compared to control. The drilling effect of roots could not explain the pore volume increase, which was several orders of magnitude larger than the volume of the roots. Leek had larger impact on volumes while petunia mostly increased soil aggregate stability. Mycorrhizae increased the soil stability and the soil volume. Earthworms alone decreased the pore volumes at any pore size, and plant roots mitigated this. Conclusions: Our results highlight (1) the large impact of soil biota on soil physical properties, (2) that their separated effects can either combine or mitigate each other and (3) that the observed changes are varying in intensity according to soil type and plant typ

Nicodrilus nocturnus and Allolobophora icterica drill compacted soils but do not decrease their bulk density – A laboratory experiment using two contrasted soils at two different compaction levels

Earthworms are known to play an important role in soil processes, especially in the regeneration of soil structure. However, quantitative studies about their role on soil physical properties are still scarce. In this study the effects of two earthworm species (Nicodrilus nocturnus as anecic, Allolobophora icterica as endogeic) following three treatments (N. nocturnus only, A. icterica only and both species with 80% weight of N. nocturnus and 20% of A. icterica) on soil specific volumes and pore properties are evaluated in mesocosms (30 cm height and 15 cm diameter) for a loamy Anthrosol and a silt loam Luvisol. The soils were repacked to bulk density observed in the field (1,15 and 1,25 g cm−3 respectively) and to compacted bulk density (1,4 and 1,5 g cm−3 respectively). Except earthworm-free controls, introduced earthworm biomass was close to 500 g.m−2. The experiment lasted 23 weeks, under constant temperature and soil matrix potential, and earthworms were fed with hay. The impact of earthworms on soil porosities and specific volumes was assessed using (i) computed tomography on mesocosm and (ii) shrinkage analysis on undisturbed cubic samples (150 cm3). Anecic surface cast bulk density was determined after wax coating. At mesocosm scale, the specific volume of compacted soils increased significantly with the anecic and mixed earthworm treatments (+1.9% for the Anthrosol and +2.6% for the Luvisol), while no change was observed with endogeics regardless of the initial level of compaction or the soil type. After subtracting the burrow volumes, the remaining soil matrix specific volume showed significant decrease with earthworms in case of loose soils, particularly with endogeics with 5.6% decrease of the specific soil matrix volume, while the compacted soil matrix was not decompacted. At undisturbed cubic sample scale, shrinkage analysis confirmed these observations with earthworms decreasing the larger structural pores and promoting a more rigid plasma. Anecic surface casts showed intermediate bulk density (0.82 cm3 g−1 for the Anthrosol and 0.73 cm3 g−1 for the Luvisol) between compacted (0.73 cm3 g−1 for the Anthrosol and 0.67 cm3 g−1 for the Luvisol) and loose (0.88 cm3 g−1 for the Anthrosol and 0.81 cm3 g−1 for the Luvisol) soil matrices. We concluded that the decompaction effect of earthworms was due to the opening of burrows at mesocosm soil scale, while the matrix volume was i) either compacted in case of loose soil especially with endogeics at the expense of the >150 µm equivalent radius structural pores or ii) unchanged in case of compacted soil. Our results support the conclusion that earthworms alone cannot regenerate the matrix of compacted soils and even compact the soil matrix in case of loose soils

Neutrophil extracellular traps are downregulated by glucocorticosteroids in lungs in an equine model of asthma

Abstract Background Severe neutrophilic asthma is poorly responsive to glucocorticosteroids (GC). Neutrophil extracellular traps (NETs) within the lungs have been associated with the severity of airway obstruction and inflammation in asthma, and were found to be unaffected by GC in vitro. As IL-17 is overexpressed in neutrophilic asthma and contributes to steroid insensitivity in different cell types, we hypothesized that NETs formation in asthmatic airways would be resistant to GC through an IL-17 mediated pathway. Methods Six neutrophilic severe asthmatic horses and six healthy controls were studied while being treated with dexamethasone. Lung function, bronchoalveolar lavage fluid (BALF) cytology and NETs formation, as well as the expression of CD11b and CD13 by blood and airway neutrophils were evaluated. The expression of IL-17 and its role in NETs formation were also studied. Results Airway neutrophils from asthmatic horses, as opposed to blood neutrophils, enhanced NETs formation, which was then decreased by GC. GC also tended to decrease the expression of CD11b in blood neutrophils, but not in airway neutrophils. IL-17 mRNA was increased in BALF cells of asthmatic horses and was unaffected by GC. However, both GC and IL-17 inhibited NETs formation in vitro. Conclusion GC decreased NETs formation in vitro and also in vivo in the lungs of asthmatic horses. However, airway neutrophil activation during asthmatic inflammation was otherwise relatively insensitive to GC. The contribution of IL-17 to these responses requires further study

Impact of two root systems, earthworms and mycorrhizae on the physical properties of an unstable silt loam luvisol and plant production

Background and aims : Soil organisms are known to engineer the soil physical properties, but their impact is difficult to assess and poorly documented. Shrinkage analysis has a good potential for such assessment. This study analyses the effects of mycorrhizae (Glomus intraradices), earthworms (Allolobophora chlorotica) and two plants, Allium porrum (leek) and Petunia hybrida (petunia), on the physical properties of an unstable loamy Luvisol, as well as the biological interactions between the soil organisms. Methods : In addition to soil organism biomass, shrinkage analysis and soil aggregate stability analysis were used to characterize the soil physical properties. Results : The soil aggregate stability, specific volume and structural pores volumes were increased with plant roots compared to control. The drilling effect of roots could not explain the pore volume increase, which was several orders of magnitude larger than the volume of the roots. Leek had larger impact on volumes while petunia mostly increased soil aggregate stability. Mycorrhizae increased the soil stability and the soil volume. Earthworms alone decreased the pore volumes at any pore size, and plant roots mitigated this. Conclusions : Our results highlight (1) the large impact of soil biota on soil physical properties, (2) that their separated effects can either combine or mitigate each other and (3) that the observed changes are varying in intensity according to soil type and plant type

Additional file 1: Figure S1. of Neutrophil extracellular traps are downregulated by glucocorticosteroids in lungs in an equine model of asthma

NETs score validation in BALF cytology. A) The scores were first validated by comparing the staining of the same extracellular DNA regions using Sytox Orange as positive control and Wright-Giemsa. Scale bars represent 100 μm. (B) Frame illustrating the software used for unbiased point counting analysis of the BALF cytology. Bottom: a magnification of the yellow area in the small up panel. Blue crosses were used as probes for NETs volume; blue crosses with green circles were used as probes for reference volume. An unbiased point counting technique using grids with 2304 crosses (randomly selected) per field was performed. Crosses marked with the letter A for NETs/MPO were used for counts. Mate method NETs volume density (Vv NET/MPO) was calculated for 7 horses as follow: VvNET/MPO = ΣPNET/MPO/Pref *Total Vv, where ΣPNET/MPO represents the sum of the points crossing onto a NET where MPO wrap around it, Pref indicated the total crosses number per field (2304) and Total Vv the known and fix field area (0,3795mm2). A minimum of 200 points was counted for ASM from at least two biopsies per horse. (C) Correlation between our developed score and quantitative unbiased method (r = 0.79; p = 0.05). (PDF 5456 kb

Validation and Pilot Testing of a Guide to Measure the Costs Associated with the Management of COVID-19 and of Healthcare Associated Infections in Residential and Long-Term Care Facilities in Quebec

Introduction: As elsewhere in the world, Quebec (Canada) is currently facing the COVID-19 pandemic. Approximately 92% of deaths have occurred among people aged over 70, and approximately 100 long-term care (LTC) centers (termed CHSLDs in Quebec) were contaminated. This alarming situation is prompting stakeholders from healthcare networks to investigate the socio-economic repercussions of COVID-19. To the best of our knowledge, there is no valid and reliable tool to measure the costs associated with the management of COVID-19 in CHSLDs. Objectives: This research protocol aims to: i) adapt and validate for use in CHSLDs a combined guide, Cout-COVID19-SLD, developed from 2 guides used in acute care; ii) pilot the Cout-COVID19-SLD guide in CHSLDs and test its feasibility and afterwards resolve any barriers to its administration, and to conduct a partial estimate of costs brought about by COVID-19. Methods: A two-part prospective study will be conducted. Phase 1 will use a Delphi approach with 14 to 17 experts to validate the content of the Cout-COVID19-SLD guide. Phase 2 will pilot test the guide in a cross-sectional study in two CHSLDs. Discussion and conclusion: This study will provide a validated guide for the systematic measurement of costs associated with the management of COVID-19 (costs of preventive measures and costs of illness) in CHSLDs. Finally, this guide will serve as a valid and reliable instrument with which to better plan future research surrounding the socio-economic impacts of COVID-19 in CHSLDs.Introduction : Le Québec (Canada) fait face à la COVID-19 comme ailleurs dans le monde. Environ 92 % des décès sont survenus chez des personnes de plus de 70 ans et une centaine de centres d’hébergement de soins de longue durée (CHSLD) ont été contaminés. Cette situation alarmante pousse le réseau de la santé à connaître les répercussions socio-économiques de la COVID-19. À notre connaissance, il n’y a pas d’outil valide et fiable pour mesurer les coûts de gestion de la COVID-19 dans les CHSLD. Objectifs : Le présent protocole vise à : i) adapter et valider pour les CHSLD une grille fusionnée, Cout-COVID19-SLD, issue de 2 grilles développées en soins aigus; ii) mettre à l’essai la grille Cout-COVID19-SLD dans les CHSLD afin d’analyser sa faisabilité, résoudre les obstacles à son administration, et procéder à une estimation partielle des coûts causés par la COVID-19. Méthodes : Une étude prospective en 2 volets sera réalisée. Le premier volet utilisera une approche Delphi auprès de 14 à 17 experts pour valider le contenu de la grille. Le second testera la grille via une étude pilote transversale dans deux CHSLD. Discussion et conclusion : Cette étude permettra d’obtenir une grille validée pour systématiser la mesure des coûts associés à la gestion de la COVID-19 (coûts de mesures préventives et de la maladie) dans les CHSLD. Enfin, cette grille servira comme un instrument valide et fiable pour mieux planifier des recherches futures sur les impacts socio-économiques de la COVID-19 dans les CHSLD