Brain Tissue Hypoxia is a Strong Predictor of Outcome after Severe Traumatic Brain Injury Independent from Elevated Intracranial Pressure

Introduction: Low brain tissue oxygen pressure (PbtO2) is associated with worse outcome in patients with severe traumatic brain injury (TBI). However, it is unclear whether brain tissue hypoxia is merely a marker of injury severity or a predictor of prognosis, independent from intracranial pressure (ICP) and injury severity. Hypothesis: We hypothesized that brain tissue hypoxia was an independent predictor of outcome in patients wih severe TBI, irrespective of elevated ICP and of the severity of cerebral and systemic injury. Methods: This observational study was conducted at the Neurological ICU, Hospital of the University of Pennsylvania, an academic level I trauma center. Patients admitted with severe TBI who had PbtO2 and ICP monitoring were included in the study. PbtO2, ICP, mean arterial pressure (MAP) and cerebral perfusion pressure (CPP = MAP-ICP) were monitored continuously and recorded prospectively every 30 min. Using linear interpolation, duration and cumulative dose (area under the curve, AUC) of brain tissue hypoxia (PbtO2 < 15 mm Hg), elevated ICP >20 mm Hg and low CPP <60 mm Hg were calculated, and the association with outcome at hospital discharge, dichotomized as good (Glasgow Outcome Score [GOS] 4-5) vs. poor (GOS 1-3), was analyzed. Results: A total of 103 consecutive patients, monitored for an average of 5 days, was studied. Brain tissue hypoxia was observed in 66 (64%) patients despite ICP was < 20 mm Hg and CPP > 60 mm Hg (72 +/- 39% and 49 +/- 41% of brain hypoxic time, respectively). Compared with patients with good outcome, those with poor outcome had a longer duration of brain hypoxia (1.7 +/- 3.7 vs. 8.3 +/- 15.9 hrs, P<0.01), as well as a longer duration (11.5 +/- 16.5 vs. 21.6 +/- 29.6 hrs, P=0.03) and a greater cumulative dose (56 +/- 93 vs. 143 +/- 218 mm Hg*hrs, P<0.01) of elevated ICP. By multivariable logistic regression, admission Glasgow Coma Scale (OR, 0.83, 95% CI: 0.70-0.99, P=0.04), Marshall CT score (OR 2.42, 95% CI: 1.42-4.11, P<0.01), APACHE II (OR 1.20, 95% CI: 1.03-1.43, P=0.03), and the duration of brain tissue hypoxia (OR 1.13; 95% CI: 1.01-1.27; P=0.04) were all significantly associated with poor outcome. No independent association was found between the AUC for elevated ICP and outcome (OR 1.01, 95% CI 0.97-1.02, P=0.11) in our prospective cohort. Conclusions: In patients with severe TBI, brain tissue hypoxia is frequent, despite normal ICP and CPP, and is associated with poor outcome, independent of intracranial hypertension and the severity of cerebral and systemic injury. Our findings indicate that PbtO2 is a strong physiologic prognostic marker after TBI. Further study is warranted to examine whether PbtO2-directed therapy improves outcome in severely head-injured patients .

Mémoire sur les frontières de Savöye du côté du Guiers et Pont de Beauvoisin

Ancien possesseur : Argenson, Antoine-René de Voyer (1722-1787 ; marquis de Paulmy d')

Conventions entre les commissaires de France et de Savoye, pour la destruction des digues construites dans le Rhône du côté de Savoye

Ancien possesseur : Argenson, Antoine-René de Voyer (1722-1787 ; marquis de Paulmy d')

Jackson County Sanitary Disposal Agency independent auditor's reports, basic financial statements and required supplementary information, schedule of findings, June 30, 2009

Audit report on the Jackson County Sanitary Disposal Agency for the year ended June 30, 2009

Early stage disc degeneration does not have an appreciable affect on stiffness and load transfer following vertebroplasty and kyphoplasty.

Vertebroplasty and kyphoplasty have been reported to alter the mechanical behavior of the treated and adjacent-level segments, and have been suggested to increase the risk for adjacent-level fractures. The intervertebral disc (IVD) plays an important role in the mechanical behavior of vertebral motion segments. Comparisons between normal and degenerative IVD motion segments following cement augmentation have yet to be reported. A microstructural finite element model of a degenerative IVD motion segment was constructed from micro-CT images. Microdamage within the vertebral body trabecular structure was used to simulate a slightly (I = 83.5% of intact stiffness), moderately (II = 57.8% of intact stiffness), and severely (III = 16.0% of intact stiffness) damaged motion segment. Six variable geometry single-segment cement repair strategies (models A-F) were studied at each damage level (I-III). IVD and bone stresses, and motion segment stiffness, were compared with the intact and baseline damage models (untreated), as well as, previous findings using normal IVD models with the same repair strategies. Overall, small differences were observed in motion segment stiffness and average stresses between the degenerative and normal disc repair models. We did however observe a reduction in endplate bulge and a redistribution in the microstructural tissue level stresses across both endplates and in the treated segment following early stage IVD degeneration. The cement augmentation strategy placing bone cement along the periphery of the vertebra (model E) proved to be the most advantageous in treating the degenerative IVD models by showing larger reductions in the average bone stresses (vertebral and endplate) as compared to the normal IVD models. Furthermore, only this repair strategy, and the complete cement fill strategy (model F), were able to restore the slightly damaged (I) motion segment stiffness above pre-damaged (intact) levels. Early stage IVD degeneration does not have an appreciable effect in motion segment stiffness and average stresses in the treated and adjacent-level segments following vertebroplasty and kyphoplasty. Placing bone cement in the periphery of the damaged vertebra in a degenerative IVD motion segment, minimizes load transfer, and may reduce the likelihood of adjacent-level fractures.

Activation mechanisms of the protease MALT1 and cleavage of one of its targets - the ribonuclease Regnase-1- in lymphocytes and lymphoma cell lines

Persistent infection induces an adaptive immune response that is mediated by T and B lymphocytes. Upon triggering with an antigen, these cells become activated and turn into fast expanding cells able to efficiently defend the host. Lymphocyte activation is controlled by a complex composed of CARMA1, BCL10 and MALT1 which regulates the NF-KB signaling pathway upon antigen triggering. Abnormally high expression or activity of either one of these three proteins can favor the development of lymphomas, while genetic defects in the pathway are associated with immunodeficiency. MALT1 was identified as a paracaspase sharing homology with other cysteine proteases, namely caspases and metacaspases. In order to be active, caspases need to dimerize. Based on their sequence similarity with MALT1, we hypothesized that dimerization might also be a mechanism of activation employed by MALT1. To address this assumption, we performed a bioinformatics modelling based on the crystal structures of several caspases. Our model suggested that the MALT1 caspase-like domain can indeed form dimers. This finding was later confirmed by several published crystal structures of MALT1. In the dimer interface of our model, we noticed the presence of charged amino acids that could potentially form salt bridges and thereby hold both monomers together. Mutation of one of these residues, E549, into alanine completely blocked the catalytic activity of MALT1. Additionally, we provided evidence for a role of E549 in promoting the MALTl-dependent growth of cells derived from diffuse large B cell lymphoma (DLBCL) of the aggressive B cell-like type (ABC). To our initial surprise, the E549A mutation showed only a partial defect in dimerization, indicating that additional residues are essential to form a stable dimer. The MALT1 crystal structures revealed a key function for E549 in stabilizing the catalytic site of the protease via its interaction with an arginine which is located next to the catalytic active cysteine. In an additional study, we discovered that MALT1 monoubiquitination is required for the catalytic activity of the protease. Interestingly, we found that the MALT1 dimer interface mutant E549A could not be monoubiquitinated. Based on these findings, we suggest that correct formation of the dimer interface is a prerequisite for monoubiquitination. In a second project, we discovered a novel target of the protease MALT1, the ribonuclease Regnase¬la It was described that the RNase activity of Regnase-1 negatively regulates immune responses. We could show that in ABC DLBCL cell lines, Regnase-1 is not only cleaved by MALT1 but also phosphorylated, at least in part, by the inhibitor of KB kinase (IKK). Both regulations appear to restrain the RNase function of Regnase-1 and thereby allow the production of pro-survival proteins. In conclusion, our studies further highlight and explain the importance of the catalytic activity of MALT1 for the activation of lymphocytes and provide additional knowledge for the development of specific drugs targeting the catalytic activity of MALT1 for immunomodulation and treatment of lymphomas.  SUMMARY IN FRENCH PhD Thesis Katrin Cabalzar 2 SUMMARY IN FRENCH Une infection persistante induit une réponse immunitaire adaptative par l'intermédiaire des lymphocytes T et B. Quand elles reconnaissent l'antigène, ces cellules sont activées et se multiplient très rapidement pour défendre efficacement l'hôte. L'activation des lymphocytes est transmise par un complexe composé de trois protéines, CARMA1, BCL10 et MALT1, qui régule la voie de signalisation NF-KB lorsque l'antigène est reconnu. L'expression ou l'activité anormalement élevée de l'une de ces trois protéines peut favoriser le développement de lymphomes, tandis que des défauts génétiques de cette voie de signalisation sont associés à l'immunodéficience. MALT1 a été identifiée comme étant une paracaspase qui partage des séquences homologues avec d'autres protéases à cystéine, comme les caspases et les métacaspases. Pour être actives, les caspases ont besoin de dimériser. Etant donné leur similarité de séquence avec MALT1, nous avons supposé que la dimérisation pouvait aussi être un mécanisme d'activation utilisé par MALT1. Pour vérifier cette hypothèse, nous avons conçu un modèle bioinformatique à partir des structures cristallographiques de plusieurs caspases. Et notre modèle a suggéré que le domaine catalytique de MALT1 était effectivement capable de former des dimères. Cette découverte a été confirmée plus tard par des publications qui montrent des structures cristallographiques dimériques de MALT1. Dans l'interface du dimère de notre modèle, nous avons remarqué la présence d'acides aminés chargés qui pouvaient former des liaisons ioniques et ainsi réunir les deux monomères. La mutation de l'un de ces résidus, E549, pour une alanine, a complètement inhibé l'activité catalytique de MALT1. De plus, nous avons mis en évidence un rôle d'E549 dans la croissance dépendante de MALT1, des cellules dérivées de lymphomes B diffus à grandes cellules (DLBCL) de sous-type cellules B actives (ABC). Dans un premier temps nous avons été surpris de constater que cette mutation révélait seulement un défaut partiel de dimérisation, ce qui indique que des acides aminés supplémentaires sont indispensables pour former un dimère stable. Les structures cristallographiques de MALT1 ont révélé un rôle primordial d'E549 dans la stabilisation du site catalytique de la protéase via son interaction avec une arginine qui se trouve à côté de la cystéine du site actif. Dans une autre étude, nous avons découvert que la monoubiquitination de MALT1 est requise pour l'activité catalytique de la protéase. A remarquer que nous avons trouvé que le mutant E549A de l'interface dimère de MALT1 n'a pas pu être monoubiquitiné. Sur la base de ces résultats, nous suggérons que la formation correcte de l'interface du dimère est une condition préalable pour la monoubiquitination. Dans un second projet, nous avons découvert une nouvelle cible de la protéase MALT1, la ribonucléase Regnase-1. Il a été décrit que l'activité RNase de Regnase-1 régulait négativement les réponses immunitaires. Nous avons pu montrer que dans les lignées cellulaires ABC DLBCL, la Regnase-1 n'était pas seulement clivée par MALT1 mais également phosphorylée, au moins en partie, par la kinase de l'inhibiteur de KB (IKK). Les deux régulations semblent supprimer la fonction RNase de Regnase-1 et permettre ainsi la stabilisation de certains ARN messagers et la production de protéines favorisant la survie. En conclusion, nos études mettent en évidence le rôle-clé de la dimérisation de MALT1 et expliquent l'importance de l'activité catalytique de MALT1 pour l'activation des lymphocytes. Ainsi, nos résultats apportent des connaissances supplémentaires pour le développement de médicaments spécifiques ciblant l'activité catalytique de MALT1, qui pourraient être utiles pour modifier les réponses immunitaires et traiter des lymphomes.

New Findings in a Global Approach to Dissect the Whole Phenotype of PLA2G6 Gene Mutations.

Mutations in PLA2G6 gene have variable phenotypic outcome including infantile neuroaxonal dystrophy, atypical neuroaxonal dystrophy, idiopathic neurodegeneration with brain iron accumulation and Karak syndrome. The cause of this phenotypic variation is so far unknown which impairs both genetic diagnosis and appropriate family counseling. We report detailed clinical, electrophysiological, neuroimaging, histologic, biochemical and genetic characterization of 11 patients, from 6 consanguineous families, who were followed for a period of up to 17 years. Cerebellar atrophy was constant and the earliest feature of the disease preceding brain iron accumulation, leading to the provisional diagnosis of a recessive progressive ataxia in these patients. Ultrastructural characterization of patients' muscle biopsies revealed focal accumulation of granular and membranous material possibly resulting from defective membrane homeostasis caused by disrupted PLA2G6 function. Enzyme studies in one of these muscle biopsies provided evidence for a relatively low mitochondrial content, which is compatible with the structural mitochondrial alterations seen by electron microscopy. Genetic characterization of 11 patients led to the identification of six underlying PLA2G6 gene mutations, five of which are novel. Importantly, by combining clinical and genetic data we have observed that while the phenotype of neurodegeneration associated with PLA2G6 mutations is variable in this cohort of patients belonging to the same ethnic background, it is partially influenced by the genotype, considering the age at onset and the functional disability criteria. Molecular testing for PLA2G6 mutations is, therefore, indicated in childhood-onset ataxia syndromes, if neuroimaging shows cerebellar atrophy with or without evidence of iron accumulation.

Factors influencing emergency delays in acute stroke management.

Early admission to hospital with minimum delay is a prerequisite for successful management of acute stroke. We sought to determine our local pre- and in-hospital factors influencing this delay. Time from onset of symptoms to admission (admission time) was prospectively documented during a 6-month period (December 2004 to May 2005) in patients consecutively admitted for an acute focal neurological deficit presented at arrival and of presumed vascular origin. Mode of transportation, patient's knowledge and correct recognition of stroke symptoms were assessed. Physicians contacted by the patients or their relatives were interviewed. The influence of referral patterns on in-hospital delays was further evaluated. Overall, 331 patients were included, 249 had an ischaemic and 37 a haemorrhagic stroke. Forty-five patients had a TIA with neurological symptoms subsiding within the first hours after admission. Median admission time was 3 hours 20 minutes. Transportation by ambulance significantly shortened admission delays in comparison with the patient's own means (HR 2.4, 95% CI 1.6-3.7). The only other factor associated with reduced delays was awareness of stroke (HR 1.9, 95% CI 1.3-2.9). Early in-hospital delays, specifically time to request CT-scan and time to call the neurologist, were shorter when the patient was referred by his family or to a lesser extent by an emergency physician than by the family physician (p < 0.04 and p < 0.01, respectively) and were shorter when he was transported by ambulance than by his own means (p < 0.01). Transportation by ambulance and referral by the patient or family significantly improved admission delays and early in-hospital management. Correct recognition of stroke symptoms further contributed to significant shortening of admission time. Educational programmes should take these findings into account.

Diagnostic performance of CT-arthrography and 1.5T MR-arthrography for the assessment of glenohumeral joint cartilage: a comparative study with arthroscopic correlation.

PURPOSE: To compare the diagnostic performance of multi-detector CT arthrography (CTA) and 1.5-T MR arthrography (MRA) in detecting hyaline cartilage lesions of the shoulder, with arthroscopic correlation. PATIENTS AND METHODS: CTA and MRA prospectively obtained in 56 consecutive patients following the same arthrographic procedure were independently evaluated for glenohumeral cartilage lesions (modified Outerbridge grade ≥2 and grade 4) by two musculoskeletal radiologists. The cartilage surface was divided in 18 anatomical areas. Arthroscopy was taken as the reference standard. Diagnostic performance of CTA and MRA was compared using ROC analysis. Interobserver and intraobserver agreement was determined by κ statistics. RESULTS: Sensitivity and specificity of CTA varied from 46.4 to 82.4 % and from 89.0 to 95.9 % respectively; sensitivity and specificity of MRA varied from 31.9 to 66.2 % and from 91.1 to 97.5 % respectively. Diagnostic performance of CTA was statistically significantly better than MRA for both readers (all p ≤ 0.04). Interobserver agreement for the evaluation of cartilage lesions was substantial with CTA (κ = 0.63) and moderate with MRA (κ = 0.54). Intraobserver agreement was almost perfect with both CTA (κ = 0.94-0.95) and MRA (κ = 0.83-0.87). CONCLUSION: The diagnostic performance of CTA and MRA for the detection of glenohumeral cartilage lesions is moderate, although statistically significantly better with CTA. KEY POINTS: ? CTA has moderate diagnostic performance for detecting glenohumeral cartilage substance loss. ? MRA has moderate diagnostic performance for detecting glenohumeral cartilage substance loss. ? CTA is more accurate than MRA for detecting cartilage substance loss.