RETRATO DE NIÑOS [Material gráfico]

Copia digital. Madrid : Ministerio de Educación, Cultura y Deporte, 201

Comparaison de deux méthodes de sélection classique avec l'haplodiploïdisation pour la résistance à la mouche de Hesse chez le blé tendre (Triticum aestivum)

L'efficacité des méthodes classiques et alternatives d'amélioration génétique repose sur l'évolution de la variabilité génétique des populations ségrégatives sous sélection. L'objectif de cette étude est de comparer l'évolution de la fréquence des gènes de résistance à la mouche de Hesse (Mayetiola destructor) sous deux méthodes classiques de sélection en comparaison avec la méthode de l'haplodiploïdisation. Les distributions et les proportions observées du caractère "résistance à la mouche de Hesse" ont été évaluées pour des lignées produites par la méthode de filiation unipare (FUP), la méthode " bulk " et l'haplodiploïdisation (DH) de quatre populations hybrides de blé tendre (Triticum aestivum). Ces populations sont issues des croisements entre des parents résistants à la mouche de Hesse marocaine et des parents sensibles mais adaptés aux conditions marocaines. Les résultats ont montré un effet marqué de la méthode d'amélioration génétique. En effet, malgré leur avancement à la génération F6, les lignées produites par les méthodes FUP et " bulk " présentent toujours un taux non négligeable d'hétérozygotie pour ce caractère alors que la méthode DH a abouti à une homozygotie parfaite. Les proportions de résistance observées chez les lignées FUP et haploïdes doublées sont approximativement les mêmes que celles théoriquement attendues. Cependant, la méthode " bulk " a permis une sélection naturelle au champ qui a favorisé le caractère résistant de manière significativeThe relative usefulness of conventional and alternative breeding methods relies on the evolution of genetic variability in segregating populations undergoing selection. The objective of this study was to compare the frequencies of genetic resistance to Hessian fly (Mayetiola destructor) in populations generated by two conventional breeding methods in comparison with lines advanced through doubled haploid method. Distribution and proportions of Hessian fly resistance were evaluated in four populations of bread wheat lines advanced through 'Single Seed Descent' (SSD), 'Bulk', and doubled-haploid (DH) methods. These populations were all derived from crosses involving resistant parents and susceptible lines adapted to Moroccan conditions. The results of this study have shown a clear effect of the breeding method. The Bulk and SSD (F6) derived lines have shown a substantial residual heterozygocity while DH method has produced completely homozygous material. The observed proportions of resistance did not deviate from expected in the populations of lines derived through SSD and DH methods while evidence of natural selection for resistance was significant in the lines derived through the Bulk method

Outcomes in Mitral Regurgitation Due to Flail Leaflets. A Multicenter European Study

Objectives: The purpose of this study was to assess incidence and predictors of events associated with nonsurgical and surgical management of severe mitral regurgitation (MR) in European institutions. Background: The management of patients with MR remains disputed, warranting multicenter studies to define clinical outcome in routine clinical practice. Methods: The MIDA (Mitral Regurgitation International DAtabase) is a registry created for multicenter study of MR with echocardiographically diagnosed flail leaflet as a model of pure, organic MR. Our cases were collected from 4 European centers. We enrolled 394 patients (age 64 ± 11 years; 67% men; 64% in New York Heart Association functional class I to II; left ventricular ejection fraction 67 ± 10%). Results: During a median follow-up of 3.9 years, linearized event rates/year under nonsurgical management were 5.4% for atrial fibrillation (AF), 8.0% for heart failure (HF), and 2.6% for death. Mitral valve (MV) surgery was performed in 315 (80%) patients (repair in 250 of 315, 80%). Perioperative mortality, defined as death within 30 days from the operation, was 0.7% (n = 2). Surgery during follow-up was independently associated with reduced risk of death (adjusted hazard ratio [HR] 0.42, 95% confidence interval [CI] 0.21 to 0.84; p = 0.014). Benefit was largely driven by MV repair (adjusted HR vs. replacement 0.37, 95% CI 0.18 to 0.76; p = 0.007). In 102 patients strictly asymptomatic and with normal ventricular function, 5-year combined incidence of AF, HF, or cardiovascular death (CVD) was 42 ± 8%. In these patients, surgery also reduced rates of CVD/HF (HR 0.26, 95% CI 0.08 to 0.89; p = 0.032). Conclusions: In this multicenter study, nonsurgical management of severe MR was associated with notable rates of adverse events. Surgery especially MV repair performed during follow-up was beneficial in reducing rates of cardiac events. These findings support surgical consideration in patients with MR due to flail leaflets for whom MV repair is feasible. © 2008 American College of Cardiology Foundation

Clinical and Prognostic Impact of a New Left Ventricular Ejection Index in Primary Mitral Regurgitation Because of Mitral Valve Prolapse

International audienceBACKGROUND:To prevent left ventricular dysfunction (LVD), surgery is recommended in patients with severe primary mitral regurgitation as soon as ejection fraction (EF) ≤60% or LV end-systolic diameter ≥40 mm. However, LVD may be concealed behind preoperative normal LVEF and LV end-systolic diameter. We sought to identify whether a new composite echocardiographic Doppler marker of the LV ejection according to the LV dilatation may predict postoperative LVD and outcome after mitral valve repair in patients with primary mitral regurgitation.METHODS AND RESULTS:Between 1991 and 2010, patients who underwent mitral valve repair for primary mitral regurgitation were studied. From preoperative echocardiography, we calculated LV ejection index (LVEI) using following formula: LVEI=indexed LV end-systolic diameter/LV outflow tract time-velocity integral. In the 278 patients included, the best correlation with postoperative LVEF was found with LVEI (r=-0.40; P1.13 was an independent predictor of postoperative LVD (P1.13 had significantly lower both survival and cardiac death-free survival (P=0.017 and P=0.008, respectively). Similar results were found in patients with preoperative LVEF≥60% (P=0.049 and P=0.016, respectively). In Cox proportional hazard model, after meticulous adjustment for cofactors, LVEI>1.13 remains independently associated with death (hazard ratio, 1.64; P=0.039) and cardiac-related death (hazard ratio, 3.27; P=0.026).CONCLUSIONS:After mitral valve repair for primary mitral regurgitation, the preoperative LVEI is a new and simple composite parameter of both LV dilatation and LV forward flow able to accurately predict postoperative LVD and outcome

Piezo1 is required for outflow tract and aortic valve development

Aims: During embryogenesis, the onset of circulatory blood flow generates a variety of hemodynamic forces which reciprocally induce changes in cardiovascular development and performance. It has been known for some time that these forces can be detected by as yet unknown mechanosensory systems which in turn promote cardiogenic events such as outflow tract and aortic valve development. PIEZO1 is a mechanosensitive ion channel present in endothelial cells where it serves to detect hemodynamic forces making it an ideal candidate to play a role during cardiac development. We sought to determine whether PIEZO1 is required for outflow tract and aortic valve development. Methods and results: By analysing heart development in zebrafish we have determined that piezo1 is expressed in the developing outflow tract where it serves to detect hemodynamic forces. In particular, we have found that mechanical forces generated during the cardiac cycle activate Piezo1 which triggers nitric oxide to be released in the outflow tract. Consequently, disrupting Piezo1 signalling leads to defective outflow tract and aortic valve development and indicates this gene may be involved in the etiology of congenital heart diseases. Based on these findings, we analysed genomic data generated from a cohort of bicuspid aortic valve patients and identified 3 probands who each harboured a novel variant in PIEZO1. Subsequent in vitro and in vivo assays indicates that these variants behave as dominant negatives leading to an inhibition of normal PIEZO1 mechanosensory activity and defective aortic valve development. Conclusion: These data indicate that the mechanosensitive ion channel piezo1 is required for OFT and aortic valve development and, furthermore, dominant negative variants of PIEZO1 appear to be associated with BAV in humans

Piezo1 is required for outflow tract and aortic valve development

Aims: During embryogenesis, the onset of circulatory blood flow generates a variety of hemodynamic forces which reciprocally induce changes in cardiovascular development and performance. It has been known for some time that these forces can be detected by as yet unknown mechanosensory systems which in turn promote cardiogenic events such as outflow tract and aortic valve development. PIEZO1 is a mechanosensitive ion channel present in endothelial cells where it serves to detect hemodynamic forces making it an ideal candidate to play a role during cardiac development. We sought to determine whether PIEZO1 is required for outflow tract and aortic valve development. Methods and results: By analysing heart development in zebrafish we have determined that piezo1 is expressed in the developing outflow tract where it serves to detect hemodynamic forces. In particular, we have found that mechanical forces generated during the cardiac cycle activate Piezo1 which triggers nitric oxide to be released in the outflow tract. Consequently, disrupting Piezo1 signalling leads to defective outflow tract and aortic valve development and indicates this gene may be involved in the etiology of congenital heart diseases. Based on these findings, we analysed genomic data generated from a cohort of bicuspid aortic valve patients and identified 3 probands who each harboured a novel variant in PIEZO1. Subsequent in vitro and in vivo assays indicates that these variants behave as dominant negatives leading to an inhibition of normal PIEZO1 mechanosensory activity and defective aortic valve development. Conclusion: These data indicate that the mechanosensitive ion channel piezo1 is required for OFT and aortic valve development and, furthermore, dominant negative variants of PIEZO1 appear to be associated with BAV in humans

Piezo1 is required for outflow tract and aortic valve development

Aims: During embryogenesis, the onset of circulatory blood flow generates a variety of hemodynamic forces which reciprocally induce changes in cardiovascular development and performance. It has been known for some time that these forces can be detected by as yet unknown mechanosensory systems which in turn promote cardiogenic events such as outflow tract and aortic valve development. PIEZO1 is a mechanosensitive ion channel present in endothelial cells where it serves to detect hemodynamic forces making it an ideal candidate to play a role during cardiac development. We sought to determine whether PIEZO1 is required for outflow tract and aortic valve development. Methods and results: By analysing heart development in zebrafish we have determined that piezo1 is expressed in the developing outflow tract where it serves to detect hemodynamic forces. In particular, we have found that mechanical forces generated during the cardiac cycle activate Piezo1 which triggers nitric oxide to be released in the outflow tract. Consequently, disrupting Piezo1 signalling leads to defective outflow tract and aortic valve development and indicates this gene may be involved in the etiology of congenital heart diseases. Based on these findings, we analysed genomic data generated from a cohort of bicuspid aortic valve patients and identified 3 probands who each harboured a novel variant in PIEZO1. Subsequent in vitro and in vivo assays indicates that these variants behave as dominant negatives leading to an inhibition of normal PIEZO1 mechanosensory activity and defective aortic valve development. Conclusion: These data indicate that the mechanosensitive ion channel piezo1 is required for OFT and aortic valve development and, furthermore, dominant negative variants of PIEZO1 appear to be associated with BAV in humans