Précision de la mesure délocalisée de l’INR pour diagnostiquer la coagulopathie post-traumatique

Background: Trauma-induced coagulopathy (TIC) is a common feature after severe trauma. Detection of TIC is based upon classic coagulation tests including international normalized ratio (INR) value. Point-of-care (POC) devices have been developed to rapidly measure INR at the bedside on whole blood. The aim of the study was to test the precision of the Coagucheck® XS Pro device for INR measurement at hospital admission after severe trauma. Methods: We conducted a prospective observational study in a French level I trauma center. From January 2015 to May 2016, 98 patients with a suspicion of a post-traumatic acute hemorrhage had POC-INR measurement on whole blood concomitantly to classic laboratory INR determination (lab-INR) on plasma at hospital admission. The agreement between the two methods in sorting three predefined categories of INR (normal coagulation, moderate TIC and severe TIC) was evaluated using the Cohen’s kappa test with a quadratic weighting. The correlation between POC-INR and lab-INR was measured using the Pearson’s coefficient. We also performed a Bland and Altman analysis. Results: The agreement between the lab-INR and the POC-INR was moderate (Kappa = 0.45 [95% CI 0.36-0.50]) and the correlation between the two measurements was also weak (Pearson’s coefficient = 0.44 [95% CI 0.27-0.59]). Using a Bland and Altman analysis, the mean difference (bias) for INR was 0.22 [95% CI 0.02-0.42], and the standard deviation (precision) of the difference was 1.01. Conclusion: POC Coagucheck® XS Pro device is not reliable to measure bedside INR. Its moderate agreement with lab-INR weakens the usefulness of such device after severe trauma.La coagulopathie post traumatique (TIC) est fréquente après un traumatisme sévère. Sa détection repose sur des tests de coagulation conventionnels, avec calcul de l’international normalized ratio (INR). Des dispositifs ont été développé pour obtenir rapidement l’INR au lit du patient, à partir d’un échantillon de sang total. L’objectif de cette étude était d’évaluer la précision du Coaguchek® XS Pro pour mesurer l’INR à l’admission à l’hôpital d’un patient victime d’un traumatisme sévère. Nous avons réalisé une étude prospective observationnelle dans un trauma center de niveau I. Entre janvier 2015 et mai 2016, chez 98 patients suspects d’une hémorragie aigüe post-traumatique, une mesure de l’INR au lit du patient sur sang total (POC-INR) était réalisée de façon concomitante aux tests conventionnels en laboratoire, déterminant l’INR sur plasma (lab-INR). L’agrément entre les deux méthodes pour classer les patients en catégories d’INR prédéfinies (coagulation normale, TIC modérée et TIC sévère) était évalué par le test kappa de Cohen avec pondération quadratique. Nous avons étudié la corrélation entre POC-INR et lab-INR, et réalisé une analyse de Bland et Altman. L’agrément entre lab-INR et POC-INR était modéré (Kappa = 0,45 [IC 95% 0.36-0.50]) et la corrélation entre les deux mesures était médiocre (coefficient de Pearson = 0.44 [IC 95% 0.27-0.59]). La différence moyenne (biais) de l’INR était de 0,22 [IC 95% 0.02-0.42], et l’écart type (précision) des différences de 1,01. Pour conclure, le Coaguchek® XS Pro n’est pas fiable pour mesurer l’INR au lit du patient. Son agrément modéré avec le lab-INR réduit l’utilité de ce type d’appareil chez le patient traumatisé sévère

Effects of resistance combinations in melon on Aphis gossypii field populations

National audienceHost-plant resistance has proven its efficiency in controlling pests, including aphids which are one of the major hemipteran pests in crops. Nevertheless, resistance-breaking biotypes have occurred in several plant-aphid systems. The aim of our field study was to investigate the impact of distinct combinations of aphid-resistance Vat gene and QTLs in melons on the density and genetic structure of field populations of the melon aphid species Aphis qossvpii. We set up field trials with melons combining (i) resistance alleles both at the Vat locus and at QTL (Vat/QTL), (ii) resistance allele at the Vat locus and susceptible alleles at QTL (Vat/-) or (iii) susceptible allele at the Vat locus and resistant alleles at QTL (-/QTL). Ali combinations had a homogenous genetic composition except at the Vat locus and QTL (Boissot et al 2010). Twelve trials were conducted in three distant melon producing areas,.: Southeastern France (SE), southwestern France (SW) and French West Indies (FWI), to take into account that aphid populations are geographically structured (Thomas et al 2012). Aphid population densities were significantly lower on Vat/QTL melon plants than on -/QTL plants over trials, revealing a strong effect of the Vat gene in situ. Conversely, no effect of the QTL was observed on aphid density. We also collected about 2800 aphids from these trials that were distributed in two classes whether they were found as isolated apterous individuals on the leaf soon after melon plantation or whether they were collected from a colony later on. Each aphid was genotyped for eight microsatellite loci. Whatever the resistance combination and area, the genetic diversity decreased dramatically during the melon development, from isolated apterous to colonies, which illustrated a strong host plant selective pressure. We also noticed a Vat gene effect in reducing the genetic diversity of both apterous populations in SE and colonies in SE and SW. Furthermore, according to a genetic clustering analysis, the 138 multilocus genotypes identified were separated in two clusters calied the NMl cluster and the Cucurbit luster. Aphids from the NMl cluster were significantly more affected by the Vat gene as apterous individuals were less numerous on Vat/QTL than on -/QTL melons and they did not develop into colonies on Vat/QTL and on Vat/- melons. ln conclusion, this field study did not provide experimental evidence that the combination of qualitative effective major gene and quantitative polygenic resistance to A. qossypii in melon improves control of the aphid populations. QTLs had no effect on demography or on clonai diversity and structure of aphid populations. On the contrary, the effect of the major resistance gene Vat was shown to de pend on the clonai diversity and structure ofthe aphid populations. However, this clonai diversity might substantially vary in time and space according to many ecological factors, which could prevent or at least slow down the spread of a resistance breaking biotype

Insight into the durability of plant resistance to aphids from a demo-genetic study of Aphis gossypii in melon crops

Resistance breakdown has been observed following the deployment of plant cultivars resistant to pests. Assessing the durability of a resistance requires long-term experiments at least at a regional scale. We collected such data for melon resistance conferred by the Vat gene cluster to melon aphids. We examined landscape- level populations of Aphis gossypii collected in 2004–2015, from melonproducing regions with and without the deployment of Vat resistance and with different climates. We conducted demo-genetic analyses of the aphid populations on Vat and non-Vat plants during the cropping seasons. The Vat resistance decreased the density of aphid populations in all areas and changed the genetic structure and composition of these populations. Two bottlenecks were identified in the dynamics of adapted clones, due to the low levels of production of dispersal morphs and winter extinction. Our results suggest that (i) Vat resistance will not be durable in the Lesser Antilles, where no bottleneck affected the dynamics of adapted clones, (ii) Vat resistance will be durable in south-west France, where both bottlenecks affected the dynamics of adapted clones and (iii) Vat resistance will be less durable in south-east France, where only one of the two bottlenecks was observed

Genetic diversity of the melon aphid Aphis gossypii Glover in different melon growing areas of France

International audienceIn melon, the Vat gene confers resistance to colonization by the Cotton-Melon aphid species, Aphis gossypii Glover. The Vat gene has been present in several melon varieties produced in south-eastern France for the past fifteen years, although as time goes by, the risk of the aphids overcoming such resistance is increasing. The study of the genetic structure of Cotton-Melon aphid populations is important in order to understand the efficacy and durability of methods to control pests through the use of resistant plants. Therefore, as outlined in the present paper, we set up field trials in geographically distant melon-producing areas in France and the French West Indies (FWI) using melon plants with the resistant allele or with the susceptible allele at the Vat locus. Samples of A. gossypii were collected from these crops in the different regions and their genetic diversity analyzed at eight microsatellite loci. We identified 33 multilocus genotypes (MLGs) that were present in multiple copies, of which five were observed in several regions of France whilst two were restricted to the FWI. The genetic diversity was high in south-eastern France, moderate in south-western and western France, and low in Guadeloupe (FWI). Differentiation between pairs of geographical populations in mainland France estimated by multilocus FST was not significant. Some MLGs (NM1 and C9) were significantly less frequent on melon with the resistant allele at the Vat locus than on melon with the susceptible allele at the Vat locus, while the frequencies of others (C6, CUC1, CUC13 and CUC25) increased significantly on melon plants with the resistant allele at the Vat locus

Combinaison gène majeur/QTL : quel intérêt pour la résistance du melon à <em>Aphis gossypii</em>

National audienceThe melon aphid, Aphis gossypii, is a major pest of many crops. Molecular markers have revealed a host race organization of the species and 8 microsatellite markers have allowed the identification of 21 multilocus genotypes (MLGs) among clones collected into colonies on Cucurbits. Aphid resistance have been identified in several melon accessions; it is controlled by a major gene, Vat, and some quantitative trait loci (QTLs). We built melon populations combining different loci of resistance, in a homogenous genetic background. They were cultivated in melon producing areas with contrasted aphid populations. Then, we showed a significant effect of the Vat gene on aphid density but non effect of the QTLs. One hundred and two MLGs were attributed to 2596 collected in trials, 54 MLGs were observed only once, five MLGs were only observed in the French West Indies, 19 MLGs were observed both in South eastern and South western France. Nevertheless, we did not observe a significant effect of the resistance loci on the diversity index of Shanon. Among clones collected into 125 colonies, we only identified 10 MLGs, five out of them were identified in clones collected on Vat-melon. The resistance loci might have an effect on the diversity of the South-eastern populations.Aphis gossypii, puceron ravageur majeur des cultures, est structuré en race d’hôtes. Huit marqueurs microsatellite ont permis d’identifier 21 génotypes multilocus (MLG)parmi les individus développant des colonies sur les Cucurbitacées. De nombreuses sources de résistance ont été identifiées chez le melon, la résistance est contrôlée par un gène majeur, Vat, et des loci à effet quantitatif (QTL). Nous avons construit des populations de melon combinant différemment ces loci dans un fond génétique homogène. Elles ont été cultivées en plein champ dans trois zones de production du melon présentant des populations de pucerons très contrastées. Sur la densité des populations, nous avons observé un effet significatif du gène Vat mais aucun effet des QTL. Parmi les 2596 pucerons collectés dans les essais, 102 MLG ont été identifiées, dont 54 une seule fois. Dix-neuf MLG ont été observés dans le Sud-est et le Sud-ouest ; seulement cinq MLG ont été observés aux Antilles (non identifiées en métropole). On n'observe pas d’effet significatif du gène Vat et des QTL sur l’indice de diversité de Shanon. Parmi 125 clones échantillonnés dans des colonies, nous avons identifié seulement 10 MLG dont 5 dans des clones échantillonnées sur des melons porteurs du gène Vat. L’effet du gène Vat et des QTL sur la diversité des populations serait restreint à la région Sud-est

Genetic data_Wingless Aphis gossypii on melon crops

Genetic data_Wingless Aphis gossypii on melon crop

Demographic data_Aphis gossypii on melon crops

Demographic data_Aphis gossypii on melon crop

Genetic data_Spring migrants Aphis gossypii on melon crops

Aphis gossypii spring migrants- collected during the 3 weeks following transplantation- on melon crops in France. MLG= MultiLocus Genotype based on 8 SSR marker

MLG Aphis gossypii_Allelic composition at 8 SRR

Size of Amplification product at each locus. 999 = missing dat