Functional dynamics of PDZ binding domains: a normal-mode analysis.

Postsynaptic density-95/disks large/zonula occludens-1 (PDZ) domains are relatively small (80-120 residues) protein binding modules central in the organization of receptor clusters and in the association of cellular proteins. Their main function is to bind C-terminals of selected proteins that are recognized through specific amino acids in their carboxyl end. Binding is associated with a deformation of the PDZ native structure and is responsible for dynamical changes in regions not in direct contact with the target. We investigate how this deformation is related to the harmonic dynamics of the PDZ structure and show that one low-frequency collective normal mode, characterized by the concerted movements of different secondary structures, is involved in the binding process. Our results suggest that even minimal structural changes are responsible for communication between distant regions of the protein, in agreement with recent NMR experiments. Thus, PDZ domains are a very clear example of how collective normal modes are able to characterize the relation between function and dynamics of proteins, and to provide indications on the precursors of binding/unbinding events.

RecA-DNA helical filaments in genetic recombination.

Paul Howard-Flanders et al proposed a molecular model of RecA-mediated recombination reaction six years ago. How does this model stand at present? In answering this question, we focus on two leading ideas of the original model, namely the proposal of the coaxial arrangement of the aligned DNA molecules within helical RecA filaments and the proposal of the ATP independence of the pairing stage of the recombination reaction. Results obtained after the model was proposed are reviewed and compared with these original assumptions and postulates of the model. EM visualization of recombining DNA molecules, studies of the energetics of the RecA-mediated recombination reaction and biochemical analysis of deproteinized joint molecules are fully consistent with a triple-stranded DNA arrangement during the RecA-mediated recombination reaction and demonstrate the ATP independence of the pairing stage of the reaction.

Nematode selenoproteome: the use of the selenocysteine insertion system to decode one codon in an animal genome?

Selenocysteine (Sec) is co-translationally inserted into selenoproteins in response to codon UGA with the help of the selenocysteine insertion sequence (SECIS) element. The number of selenoproteins in animals varies, with humans having 25 and mice having 24 selenoproteins. To date, however, only one selenoprotein, thioredoxin reductase, has been detected in Caenorhabditis elegans, and this enzyme contains only one Sec. Here, we characterize the selenoproteomes of C.elegans and Caenorhabditis briggsae with three independent algorithms, one searching for pairs of homologous nematode SECIS elements, another searching for Cys- or Sec-containing homologs of potential nematode selenoprotein genes and the third identifying Sec-containing homologs of annotated nematode proteins. These methods suggest that thioredoxin reductase is the only Sec-containing protein in the C.elegans and C.briggsae genomes. In contrast, we identified additional selenoproteins in other nematodes. Assuming that Sec insertion mechanisms are conserved between nematodes and other eukaryotes, the data suggest that nematode selenoproteomes were reduced during evolution, and that in an extreme reduction case Sec insertion systems probably decode only a single UGA codon in C.elegans and C.briggsae genomes. In addition, all detected genes had a rare form of SECIS element containing a guanosine in place of a conserved adenosine present in most other SECIS structures, suggesting that in organisms with small selenoproteomes SECIS elements may change rapidly.

Quality Assessment of Cardiac Magnetic Resonance Images at 1.5/3.0 T: Description and Validation of Standardized Criteria

PURPOSE: Cardiovascular magnetic resonance (CMR) has become a robust and important diagnostic imaging modality in cardiovascular medicine. However,insufficient image quality may compromise its diagnostic accuracy. No standardized criteria are available to assess the quality of CMR studies. We aimed todescribe and validate standardized criteria to evaluate the quality of CMR studies including: a) cine steady-state free precession, b) delayed gadoliniumenhancement, and c) adenosine stress first-pass perfusion. These criteria will serve for the assessment of the image quality in the setting of the Euro-CMR registry.METHOD AND MATERIALS: First, a total of 45 quality criteria were defined (35 qualitative criteria with a score from 0-3, and 10 quantitative criteria). Thequalitative score ranged from 0 to 105. The lower the qualitative score, the better the quality. The quantitative criteria were based on the absolute signal intensity (delayed enhancement) and on the signal increase (perfusion) of the anterior/posterior left ventricular wall after gadolinium injection. These criteria were then applied in 30 patients scanned with a 1.5T system and in 15 patients scanned with a 3.0T system. The examinations were jointly interpreted by 3 CMR experts and 1 study nurse. In these 45 patients the correlation between the results of the quality assessment obtained by the different readers was calculated.RESULTS: On the 1.5T machine, the mean quality score was 3.5. The mean difference between each pair of observers was 0.2 (5.7%) with a mean standarddeviation of 1.4. On the 3.0T machine, the mean quality score was 4.4. The mean difference between each pair of onservers was 0.3 (6.4%) with a meanstandard deviation of 1.6. The quantitative quality assessments between observers were well correlated for the 1.5T machine: R was between 0.78 and 0.99 (pCONCLUSION: The described criteria for the assessment of CMR image quality are robust and have a low inter-observer variability, especially on 1.5T systems.CLINICAL RELEVANCE/APPLICATION: These criteria will allow the standardization of CMR examinations. They will help to improve the overall quality ofexaminations and the comparison between clinical studies.

FANCM regulates DNA chain elongation and is stabilized by S-phase checkpoint signalling.

FANCM binds and remodels replication fork structures in vitro. We report that in vivo, FANCM controls DNA chain elongation in an ATPase-dependent manner. In the presence of replication inhibitors that do not damage DNA, FANCM counteracts fork movement, possibly by remodelling fork structures. Conversely, through damaged DNA, FANCM promotes replication and recovers stalled forks. Hence, the impact of FANCM on fork progression depends on the underlying hindrance. We further report that signalling through the checkpoint effector kinase Chk1 prevents FANCM from degradation by the proteasome after exposure to DNA damage. FANCM also acts in a feedback loop to stabilize Chk1. We propose that FANCM is a ringmaster in the response to replication stress by physically altering replication fork structures and by providing a tight link to S-phase checkpoint signalling.

Quantification of myocardial blood flow with 82Rb positron emission tomography: clinical validation with 15O-water.

PURPOSE: Quantification of myocardial blood flow (MBF) with generator-produced (82)Rb is an attractive alternative for centres without an on-site cyclotron. Our aim was to validate (82)Rb-measured MBF in relation to that measured using (15)O-water, as a tracer 100% of which can be extracted from the circulation even at high flow rates, in healthy control subject and patients with mild coronary artery disease (CAD). METHODS: MBF was measured at rest and during adenosine-induced hyperaemia with (82)Rb and (15)O-water PET in 33 participants (22 control subjects, aged 30 ± 13 years; 11 CAD patients without transmural infarction, aged 60 ± 13 years). A one-tissue compartment (82)Rb model with ventricular spillover correction was used. The (82)Rb flow-dependent extraction rate was derived from (15)O-water measurements in a subset of 11 control subjects. Myocardial flow reserve (MFR) was defined as the hyperaemic/rest MBF. Pearson's correlation r, Bland-Altman 95% limits of agreement (LoA), and Lin's concordance correlation ρ (c) (measuring both precision and accuracy) were used. RESULTS: Over the entire MBF range (0.66-4.7 ml/min/g), concordance was excellent for MBF (r = 0.90, [(82)Rb-(15)O-water] mean difference ± SD = 0.04 ± 0.66 ml/min/g, LoA = -1.26 to 1.33 ml/min/g, ρ(c) = 0.88) and MFR (range 1.79-5.81, r = 0.83, mean difference = 0.14 ± 0.58, LoA = -0.99 to 1.28, ρ(c) = 0.82). Hyperaemic MBF was reduced in CAD patients compared with the subset of 11 control subjects (2.53 ± 0.74 vs. 3.62 ± 0.68 ml/min/g, p = 0.002, for (15)O-water; 2.53 ± 1.01 vs. 3.82 ± 1.21 ml/min/g, p = 0.013, for (82)Rb) and this was paralleled by a lower MFR (2.65 ± 0.62 vs. 3.79 ± 0.98, p = 0.004, for (15)O-water; 2.85 ± 0.91 vs. 3.88 ± 0.91, p = 0.012, for (82)Rb). Myocardial perfusion was homogeneous in 1,114 of 1,122 segments (99.3%) and there were no differences in MBF among the coronary artery territories (p > 0.31). CONCLUSION: Quantification of MBF with (82)Rb with a newly derived correction for the nonlinear extraction function was validated against MBF measured using (15)O-water in control subjects and patients with mild CAD, where it was found to be accurate at high flow rates. (82)Rb-derived MBF estimates seem robust for clinical research, advancing a step further towards its implementation in clinical routine.

EuroCMR (European Cardiovascular Magnetic Resonance) registry: results of the German pilot phase.

OBJECTIVES: During its German pilot phase, the EuroCMR (European Cardiovascular Magnetic Resonance) registry sought to evaluate indications, image quality, safety, and impact on patient management of routine CMR. BACKGROUND: CMR has a broad range of applications and is increasingly used in clinical practice. METHODS: This was a multicenter registry with consecutive enrollment of patients in 20 German centers. RESULTS: A total of 11,040 consecutive patients were enrolled. Eighty-eight percent of patients received gadolinium-based contrast agents. Twenty-one percent underwent adenosine perfusion, and 11% high-dose dobutamine-stress CMR. The most important indications were workup of myocarditis/cardiomyopathies (32%), risk stratification in suspected coronary artery disease/ischemia (31%), as well as assessment of viability (15%). Image quality was good in 90.1%, moderate in 8.1%, and inadequate in 1.8% of cases. Severe complications occurred in 0.05%, and were all associated with stress testing. No patient died during or due to CMR. In nearly two-thirds of patients, CMR findings impacted patient management. Importantly, in 16% of cases the final diagnosis based on CMR was different from the diagnosis before CMR, leading to a complete change in management. In more than 86% of cases, CMR was capable of satisfying all imaging needs so that no further imaging was required. CONCLUSIONS: CMR is frequently performed in clinical practice in many participating centers. The most important indications are workup of myocarditis/cardiomyopathies, risk stratification in suspected coronary artery disease/ischemia, and assessment of viability. CMR imaging as used in the centers of the pilot registry is a safe procedure, has diagnostic image quality in 98% of cases, and its results have strong impact on patient management.

Myocardial flow reserve by Rb-82 cardiac PET improves the selection of patients eligible for invasive coronary angiography

Aim: We asked whether myocardial flow reserve (MFR) by Rb-82 cardiac PET improve the selection of patients eligible for invasive coronary angiography (ICA). Material and Methods: We enrolled 26 consecutive patients with suspected or known coronary artery disease who performed dynamic Rb-82 PET/CT and (ICA) within 60 days; 4 patients who underwent revascularization or had any cardiovascular events between PET and ICA were excluded. Myocardial blood flow at rest (rMBF), at stress with adenosine (sMBF) and myocardial flow reserve (MFR=sMBF/rMBF) were estimated using the 1-compartment Lortie model (FlowQuant) for each coronary arteries territories. Stenosis severity was assessed using computer-based automated edge detection (QCA). MFR was divided in 3 groups: G1:MFR<1.5, G2:1.5≤MFR<2 and G3:2≤MFR. Stenosis severity was graded as non-significant (<50% or FFR ≥0.8), intermediate (50%≤stenosis<70%) and severe (≥70%). Correlation between MFR and percentage of stenosis were assessed using a non-parametric Spearman test. Results: In G1 (44 vessels), 17 vessels (39%) had a severe stenosis, 11 (25%) an intermediate one, and 16 (36%) no significant stenosis. In G2 (13 vessels), 2 (15%) vessels presented a severe stenosis, 7 (54%) an intermediate one, and 4 (31%) no significant stenosis. In G3 (9 vessels), 0 vessel presented a severe stenosis, 1 (11%) an intermediate one, and 8 (89%) no significant stenosis. Of note, among 11 patients with 3-vessel low MFR<1.5 (G1), 9/11 (82%) had at least one severe stenosis and 2/11 (18%) had at least one intermediate stenosis. There was a significant inverse correlation between stenosis severity and MFR among all 66 territories analyzed (rho= -0.38, p=0.002). Conclusion: Patients with MFR>2 could avoid ICA. Low MFR (G1, G2) on a vessel-based analysis seems to be a poor predictor of severe stenosis severity. Patients with 3-vessel low MFR would benefit from ICA as they are likely to present a significant stenosis in at least one vessel.

ParA2, a Vibrio cholerae chromosome partitioning protein, forms left-handed helical filaments on DNA.

Most bacterial chromosomes contain homologs of plasmid partitioning (par) loci. These loci encode ATPases called ParA that are thought to contribute to the mechanical force required for chromosome and plasmid segregation. In Vibrio cholerae, the chromosome II (chrII) par locus is essential for chrII segregation. Here, we found that purified ParA2 had ATPase activities comparable to other ParA homologs, but, unlike many other ParA homologs, did not form high molecular weight complexes in the presence of ATP alone. Instead, formation of high molecular weight ParA2 polymers required DNA. Electron microscopy and three-dimensional reconstruction revealed that ParA2 formed bipolar helical filaments on double-stranded DNA in a sequence-independent manner. These filaments had a distinct change in pitch when ParA2 was polymerized in the presence of ATP versus in the absence of a nucleotide cofactor. Fitting a crystal structure of a ParA protein into our filament reconstruction showed how a dimer of ParA2 binds the DNA. The filaments formed with ATP are left-handed, but surprisingly these filaments exert no topological changes on the right-handed B-DNA to which they are bound. The stoichiometry of binding is one dimer for every eight base pairs, and this determines the geometry of the ParA2 filaments with 4.4 dimers per 120 A pitch left-handed turn. Our findings will be critical for understanding how ParA proteins function in plasmid and chromosome segregation.

Postpacing abnormal repolarization in catecholaminergic polymorphic ventricular tachycardia associated with a mutation in the cardiac ryanodine receptor gene.

BACKGROUND Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an arrhythmogenic disease for which electrophysiological studies (EPS) have shown to be of limited value.OBJECTIVE This study presents a CPVT family in which marked postpacing repolarization abnormalities during EPS were the only consistent phenotypic manifestation of ryanodine receptor (RyR2) mutation carriers.METHODS The study was prompted by the observation of transient marked QT prolongation preceding initiation of ventricular fibrillation during atrial fibrillation in a boy with a family history of sudden cardiac death (SCD). Family members underwent exercise and pharmacologic electrocardiographic testing with epinephrine, adenosine, and flecainide. Noninvasive clinical test results were normal in 10 patients evaluated, except for both epinephrine- and exercise-induced ventricular arrhythmias in 1. EPS included bursts of ventricular pacing and programmed ventricular extrastimulation reproducing short-long sequences. Genetic screening involved direct sequencing of genes involved in long QT syndrome as well as RyR2.RESULTS Six patients demonstrated a marked increase in QT interval only in the first beat after cessation of ventricular pacing and/or extrastimulation. All 6 patients were found to have a heterozygous missense mutation (M4109R) in RyR2. Two of them, presenting with aborted SCD, also had a second missense mutation (I406T- RyR2). Four family members without RyR2 mutations did not display prominent postpacing QT changes.CONCLUSION M4109R- RyR2 is associated with a high incidence of SCD. The contribution of I406T to the clinical phenotype is unclear. In contrast to exercise testing, marked postpacing repolarization changes in a single beat accurately predicted carriers of M4109R- RyR2 in this family.

ATP release due to Thy-1-integrin binding induces P2X7-mediated calcium entry required for focal adhesion formation.

Thy-1, an abundant mammalian glycoprotein, interacts with αvβ3 integrin and syndecan-4 in astrocytes and thus triggers signaling events that involve RhoA and its effector p160ROCK, thereby increasing astrocyte adhesion to the extracellular matrix. The signaling cascade includes calcium-dependent activation of protein kinase Cα upstream of Rho; however, what causes the intracellular calcium transients required to promote adhesion remains unclear. Purinergic P2X7 receptors are important for astrocyte function and form large non-selective cation pores upon binding to their ligand, ATP. Thus, we evaluated whether the intracellular calcium required for Thy-1-induced cell adhesion stems from influx mediated by ATP-activated P2X7 receptors. Results show that adhesion induced by the fusion protein Thy-1-Fc was preceded by both ATP release and sustained intracellular calcium elevation. Elimination of extracellular ATP with Apyrase, chelation of extracellular calcium with EGTA, or inhibition of P2X7 with oxidized ATP, all individually blocked intracellular calcium increase and Thy-1-stimulated adhesion. Moreover, Thy-1 mutated in the integrin-binding site did not trigger ATP release, and silencing of P2X7 with specific siRNA blocked Thy-1-induced adhesion. This study is the first to demonstrate a functional link between αvβ3 integrin and P2X7 receptors, and to reveal an important, hitherto unanticipated, role for P2X7 in calcium-dependent signaling required for Thy-1-stimulated astrocyte adhesion.

RecA-mediated strand exchange traverses substitutional heterologies more easily than deletions or insertions.

RecA protein in bacteria and its eukaryotic homolog Rad51 protein are responsible for initiation of strand exchange between homologous DNA molecules. This process is crucial for homologous recombination, the repair of certain types of DNA damage and for the reinitiation of DNA replication on collapsed replication forks. We show here, using two different types of in vitro assays, that in the absence of ATP hydrolysis RecA-mediated strand exchange traverses small substitutional heterologies between the interacting DNAs, whereas small deletions or insertions block the ongoing strand exchange. We discuss evolutionary implications of RecA selectivity against insertions and deletions and propose a molecular mechanism by which RecA can exert this selectivity.

Incidence et traitement des lymphocèles après greffe rénale

1.1. La greffe de rein La greffe d'organes a révolutionné la médecine. De tout le temps elle a suscité les fantasmes et les rêves : la pratique est ancestrale ; elle remonte au 3ème siècle lorsque Saint Côme et Saint Damien réalisent pour la première fois une greffe de jambe de Maure sur un patient. Il faudra néanmoins attendre le 20ème siècle pour voir la transplantation se réaliser plus concrètement avec succès et se généraliser. A Vienne, en 1902, le Dr. Ulmann (1861-1937) pratique la toute première autogreffe de rein sur un chien. Il replace le rein de l'animal au niveau du cou, pratiquant une anastomose vasculaire. Depuis, les tentatives se multiplient et peu après le Dr. Von Decastello, pratique la première transplantation chien-chien. Par la suite, en associa- tion avec le Dr. Ulmann la première greffe entre un chien et une chèvre aura lieu, avec un certain succès. En effet, elle a permis à l'animal receveur de produire de l'urine. L'avancée majeure durant ce début de siècle fut le développement d'une nouvelle technique de suture vasculaire par le Dr. Carrel, qui obtiendra le prix Nobel en 1912. Son élève, le Dr. Jaboulay (1860-1913) a réalisé plusieurs tentatives de xénogreffes rénales. Il pratiquera en 1906 les deux premières xénogreffes en utilisant un cochon et une chèvre comme donneurs. Le greffon fut respectivement placé au niveau de la cuisse et du bras des patients. La fonction rénale durera une heure. En 1909 Ernest Unger (1875-1938) transplanta un rein de fox-terrier sur un boxer, avec une production d'urine pendant 14 jours. Durant la même année le Dr. Unger a pratiqué une xénogreffe en transplantant un rein de nouveau né sur un babouin, cette intervention se terminant par la mort de l'animal. Un autre essai de greffe singe à humain, pratiqué sur une femme mourant de défaillance rénale, a fait comprendre à Unger qu'il y a des barrières biologiques dans la transplantation, mais que la greffe rénale est techniquement faisable. En 1914, J.B. Murphy découvre l'importance de la rate et de la moelle osseuse dans la réponse immune. En 1933 et 1949 en Ukraine, les premières allogreffes humaines de reins sont pratiquées par le chirurgien soviétique Yu Yu Voronoy. Malheureuse- ment aucune fonction rénale des greffons n'a été observée. Après une période de « stagnation scientifique » générale qui durera à peu près 10 ans, l'intérêt pour la transplantation refait surface dans les années 1950. Deux équipes de chirurgien se forment : une à Boston et l'autre à Paris. De nombreux cas d'allogreffes humaines sans immunosuppression sont documentés de 1950 à 1953. Malheureusement chaque opération aboutit à un échec, ceci dû aux phénomènes du rejet. M. Simonsen et WJ. Dempster découvrent qu'un mécanisme immun est à la base du rejet. Ils établissent aussi que la position pelvienne était meilleure que la position plus superficielle. Grâce aux découvertes dans le domaine du rejet et les nombreux progrès techniques, une allogreffe entre vrais jumeaux est pratiquée à Boston en 1954. L'opération est un succès total et permet de contrer toutes les hypothèses négatives avancées par certains groupes de travail. Depuis 1948, de nombreux travaux dans le domaine de l'immunosuppression ont été entrepris. La découverte de l'action immunosuppressive de la cortisone permet son instauration dans le traitement anti-rejet, malheureusement avec peu de succès. En effet, l'irradiation totale reste la méthode de choix jusqu'en 1962, date de l'apparition de l'Azaothioprine (Imuran®). La découverte de l'Azaothioprine, permet d'avancer de nouvelles hypothèses concernant le rejet : en évitant le rejet post-opératoire aigu, une protection et une adaptation au receveur pourraient être modulées par l'immunosuppression. Dans les années 1960, l'apparition des immunosuppresseurs de synthèse permet de développer de nouvelles lignes de traitement. Le Dr.Starzl et ses collègues, découvrent l'efficacité d'un traitement combiné de Prednisone et d'Azathioprine qui devient alors le standard d'immunosuppression post greffe durant cette période. Les années 60 et 70 sont des années d'optimisme. La prise en charge des patients s'améliore, le développement de la dialyse permet de maintenir en vie les patients avant la greffe, les techniques de conservation des organes s'améliorent, la transplantation élargit son domaine d'action avec la première greffe de coeur en 1968. Le typage tissulaire permet de déterminer le type d'HLA et la compatibilité entre le re- ceveur et le donneur afin de minimiser les risques de rejet aigu. Les années 1970 se caractérisent par deux amélioration majeures : celle du typage HLA-DR et l'apparition des inhibiteurs de la calcineurine (Cyclosporine A). Ce dernier restera l'agent de premier choix jusqu'aux alentours des années 1990 où apparaissaient de nouveaux immunosuppresseurs, tels que les inhibiteurs mTOR (siroli- mus) et les inhibiteurs de l'inosine monophosphate déshydrogénase (mycophénolate mofétil), par exemple. En conclusion, la transplantation rénale a été une des premières transplantations d'organes solides pratiquées sur l'homme avec de nombreux essais cliniques impliquant une multitude d'acteurs. Malgré des périodes de hauts et de bas, les avancements techniques ont été notables, ce qui a été très favorable en terme de survie pour les patients nécessitant une greffe. 1.2. Le lymphocèle La greffe rénale, comme toute autre acte chirurgical, comporte des risques et une morbidité spécifique. Le lymphocèle a la prévalence la plus élevée, qui peut aller de 0.6 à 51% 1-3 avec des variations entre les études. Le lymphocèle est défini comme une collection post opératoire de liquide lymphatique dans une cavité non épithélialisée et n'est pas causée par une fuite urinaire ou une hémorragie1, 4. Historiquement, le lymphocèle a été décrit pour la première fois dans la littérature médicale dans les années 1950, par Kobayashi et Inoue5 en chirurgie gynécologique. Par la suite Mori et al.6 en 1960 documentent la première série d'analyse de lymphocèles. En 1969 le lymphocèle est décrit pour la première fois par Inociencio et al.7 en tant que complication de greffe rénale. Sa pathogénèse n'est pas complètement élucidée, cependant plusieurs facteurs de risque ont été identifiés tels que : la ligature inadéquate des vaisseaux lymphatiques lors de la dissection des vaisseaux iliaques du donneur et de la préparation du greffon, le BMI, les diurétiques, l'anticoagulation (héparine), les hautes doses de stéoïdes, certains agents immunosuppresseurs (sirolimus), le diabète, les problèmes de cicatrisation, une hypoalbuminémie, une chirurgie rétropéritonéale préalable et le rejet aigu de greffe. (Tableau 1) Une symptomatologie peut être présente ou absente : elle découle directement de la localisation et de la taille de la collection8, 9, 10. Lorsqu'on se trouve devant un tableau de lymphocèle asymptomatique, la découverte se fait de manière fortuite lors d'un contrôle de suivi de greffe11, 12 cliniquement ou par échographie. En cas de lymphocèle non significatif cela ne requiert aucun traitement. Au contraire, lorsqu'il atteint une certaines taille il provoque un effet de masse et de compression qui provoque la symptomatologie. Cette dernière est peu spécifique et apparait en moyenne entre 2 semaines et 6 mois 13 après la greffe. Le patient va se présenter avec un tableau pouvant aller de la simple douleur abdominale en passant par un oedème du membre inférieur ou, dans de plus rares cas, une thrombose veineuse profonde sera le seul signe consécutif au lymphocèle14, 15. La plupart du temps on observera des valeurs de créatinine élevées, signant une souffrance rénale. Le diagnostic du lymphocèle peut se faire selon plusieurs techniques. La plus utilisée est la ponction à l'aiguille fine sous guidage ultrasonographique4. L'analyse du liquide ponctionné permet de différencier un lymphocèle d'un urinome. Les autres techniques existantes sont : la ponction après injection de carmin d'indigo15, un pyelogramme intraveineux et un lymphangiogramme16, le CT-Scan ou l'IRM15. Le dosage sanguin d'IL6 et IL8 est parfois utilisé pour déterminer si le lymphocèle est infecté.15 Suite à l'apparition d'une collection symptomatique; le rein transplanté peut être dans une situation à risque pour laquelle un traitement doit être entrepris. A l'heure actuelle, il n'existe pas de solution universelle dans la prévention et le traitement de ce type de complication. Les solutions sont multiples et dépendent principalement de la localisation et de la taille de la collection. Pendant de nombreuses années, le seul traitement du lymphocèle a été celui de l'aspiration percutanée simple. Cette dernière conduit cependant à un taux de récidive de presque 100%.17 Cette technique reste une solution utilisée principalement à visée diagnostique18, 19, 20, 21 ou pour soulager les patients à court terme15. Pour améliorer l'efficacité de cette technique on a fait appel à des agents sclérosants comme l'éthanol, la povidone-iodine, la tétracycline, la doxycycline ou de la colle de fibrine. Des complications chirurgicales ont cependant été rapportées, pouvant aller jusqu'au rejet de greffe22. La fenestration par laparoscopie a été décrite pour la première fois en 1991 par McCullough et al.23 Cette technique reste, de nos jours, la technique la plus utilisée pour le traitement du lymphocèle. Elle a de nombreux avantages : un temps de convalescence court, des pertes de sang minimes et une réalimentation rapide24, 25. On constate en outre la quasi absence de récidives après traitement11, 26. L'évaluation radiologique est très importante, car la marsupialisation par laparoscopie est limitée par l'emplacement et le volume de la collection. Ainsi, on évitera ce type de traite- ment lorsque la collection se situera postérieurement, à proximité de la vessie, de l'uretère ou du hile rénal. Dans ces situations, la laparotomie s'impose malgré l'augmentation de la morbidité liée à cette technique24. Actuellement on cherche à trouver une technique universelle du traitement des lymphocèles avec la chirurgie la moins invasive possible et le taux de récidive le plus faible possible. Malgré ses li- mites, la fenestration par laparoscopie apparaît comme une très bonne solution. Cette étude consiste en une évaluation rétrospective des traitements chirurgicaux de cette complication post-opératoire de la greffe rénale au CHUV (Centre Hospitalier Universitaire Vaudois) de 2003 à 2011. Le but est de recenser et analyser les différentes techniques que l'on observe actuellement dans la littérature et pouvoir ainsi proposer une technique idéale pour le CHUV.