Double-bundle transtibial posterior cruciate ligament reconstruction with a tendon-patellar bone-semitendinosus tendon autograft: clinical results with a minimum of 2 years' follow-up.

PURPOSE: The purpose of this study was to evaluate the clinical and subjective outcomes after arthroscopic-assisted double-bundle posterior cruciate ligament (PCL) reconstruction. METHODS: A series of 15 patients with grade III isolated chronic PCL tears underwent double-bundle PCL reconstruction. Of these patients, 8 (53%) had simultaneous fractures. The mean time from accident to surgery was 10.8 months (range, 8 to 15 months). The mean age at the time of surgery was 28.2 years (range, 17 to 43 years). All of the patients reported knee insecurity during activities of daily living or light sporting activities, with associated anterior knee pain in 5 patients. Preoperatively, posterolateral or posteromedial corner injuries were ruled out through accurate clinical examination. The knees were assessed before surgery and at a mean follow-up of 3.2 years (range, 2 to 5 years) with a physical examination, 4 different rating scales, and stress radiographs obtained with a Telos device (Telos, Marburg, Germany). RESULTS: Postoperative physical examination revealed a reduction of the posterior drawer and tibial step-off in all cases, although the posterior laxity was not completely normalized. Nevertheless, the patients were subjectively better after surgery. The subjective International Knee Documentation Committee score was significantly ameliorated. With regard to the objective International Knee Documentation Committee score, 6 knees (40%) were graded as abnormal because of posterior displacement of 6 mm or greater on follow-up stress radiographs with the Telos device. On the Lysholm knee scoring scale, the score was excellent in 13% of patients and good in 87%. The mean score on the Hospital for Special Surgery knee ligament rating scale was 85.8. The Tegner activity score showed an amelioration after surgery, but no patient resumed his or her preinjury level of activities. The postoperative stress radiographs revealed an improvement in posterior instability of 50% or more in all but 3 knees (20%). CONCLUSIONS: Our technique of double-bundle PCL reconstruction produced a significant reduction in knee symptoms and allowed the patients to return to moderate or strenuous activity, although the posterior tibial translation was not completely normalized and our results appear to be no better than the results of single-bundle PCL reconstruction. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Incidence and risk factors for Contegra graft infection following right ventricular outflow tract reconstruction: long-term results.

OBJECTIVES: The aim of this study was to evaluate the risk factors associated with Contegra graft (Medtronic Minneapolis, MN, USA) infection after reconstruction of the right ventricular outflow tract. METHODS: One hundred and six Contegra grafts were implanted between April 1999 and April 2010 for the Ross procedure (n = 46), isolated pulmonary valve replacement (n = 32), tetralogy of Fallot (n = 24), double-outlet right ventricle (n = 7), troncus arteriosus (n = 4), switch operation (n = 1) and redo of pulmonary valve replacement (n = 2). The median age of the patients was 13 years (range 0-54 years). A follow-up was completed in all cases with a median duration of 7.6 years (range 1.7-12.7 years). RESULTS: There were 3 cases of in-hospital mortality. The survival rate during 7 years was 95.7%. Despite the lifelong endocarditis prophylaxis, Contegra graft infection was diagnosed in 12 (11.3%) patients at a median time of 4.4 years (ranging from 0.4 to 8.7 years). Univariate analysis of preoperative, perioperative and postoperative variables was performed and the following risk factors for time to infection were identified: female gender with a hazard ratio (HR) of 0.19 (P = 0.042), systemic-to-pulmonary shunt (HR 6.46, P < 0.01), hypothermia (HR 0.79, P = 0.014), postoperative renal insufficiency (HR 11.97, P = 0.015) and implantation of permanent pacemaker during hospitalization (HR 5.29, P = 0.075). In 2 cases, conservative therapy was successful and, in 10 patients, replacement of the infected valve was performed. The Contegra graft was replaced by a homograft in 2 cases and by a new Contegra graft in 8 cases. Cox's proportional hazard model indicated that time to graft infection was significantly associated with tetralogy of Fallot (HR 0.06, P = 0.01), systemic-to-pulmonary shunt (HR 64.71, P < 0.01) and hypothermia (HR 0.77, P < 0.01). CONCLUSION: Contegra graft infection affected 11.3% of cases in our cohort, and thus may be considered as a frequent entity that can be predicted by both intraoperative and early postoperative factors. After the diagnosis of infection associated with the Contegra graft was confirmed, surgical treatment was the therapy of choice.

Multiple interacting cell death mechanisms in the mediation of excitotoxicity and ischemic brain damage: A challenge for neuroprotection.

There is currently no approved neuroprotective pharmacotherapy for acute conditions such as stroke and cerebral asphyxia. One of the reasons for this may be the multiplicity of cell death mechanisms, because inhibition of a particular mechanism leaves the brain vulnerable to alternative ones. It is therefore essential to understand the different cell death mechanisms and their interactions. We here review the multiple signaling pathways underlying each of the three main morphological types of cell death - apoptosis, autophagic cell death and necrosis - emphasizing their importance in the neuronal death that occurs during cerebral ischemia and hypoxia-ischemia, and we analyze the interactions between the different mechanisms. Finally, we discuss the implications of the multiplicity of cell death mechanisms for the design of neuroprotective strategies.

Assessment of transcript reconstruction methods for RNA-seq.

We evaluated 25 protocol variants of 14 independent computational methods for exon identification, transcript reconstruction and expression-level quantification from RNA-seq data. Our results show that most algorithms are able to identify discrete transcript components with high success rates but that assembly of complete isoform structures poses a major challenge even when all constituent elements are identified. Expression-level estimates also varied widely across methods, even when based on similar transcript models. Consequently, the complexity of higher eukaryotic genomes imposes severe limitations on transcript recall and splice product discrimination that are likely to remain limiting factors for the analysis of current-generation RNA-seq data.

Visual functions in the healthy and schizophrenic brain : from stimulus control to illusory perceptions using electrical neuroimaging

ABSTRACT (FRENCH)Ce travail de thèse basé sur le système visuel chez les sujets sains et chez les patients schizophrènes, s'articule autour de trois articles scientifiques publiés ou en cours de publication. Ces articles traitent des sujets suivants : le premier article présente une nouvelle méthode de traitement des composantes physiques des stimuli (luminance et fréquence spatiale). Le second article montre, à l'aide d'analyses de données EEG, un déficit de la voie magnocellulaire dans le traitement visuel des illusions chez les patients schizophrènes. Ceci est démontré par l'absence de modulation de la composante PI chez les patients schizophrènes contrairement aux sujets sains. Cette absence est induite par des stimuli de type illusion Kanizsa de différentes excentricités. Finalement, le troisième article, également à l'aide de méthodes de neuroimagerie électrique (EEG), montre que le traitement des contours illusoires se trouve dans le complexe latéro-occipital (LOC), à l'aide d'illusion « misaligned gratings ». De plus il révèle que les activités démontrées précédemment dans les aires visuelles primaires sont dues à des inférences « top- down ».Afin de permettre la compréhension de ces trois articles, l'introduction de ce manuscrit présente les concepts essentiels. De plus des méthodes d'analyses de temps-fréquence sont présentées. L'introduction est divisée en quatre parties : la première présente le système visuel depuis les cellules retino-corticales aux deux voix du traitement de l'information en passant par les régions composant le système visuel. La deuxième partie présente la schizophrénie par son diagnostic, ces déficits de bas niveau de traitement des stimuli visuel et ces déficits cognitifs. La troisième partie présente le traitement des contours illusoires et les trois modèles utilisés dans le dernier article. Finalement, les méthodes de traitement des données EEG seront explicitées, y compris les méthodes de temps-fréquences.Les résultats des trois articles sont présentés dans le chapitre éponyme (du même nom). De plus ce chapitre comprendra les résultats obtenus à l'aide des méthodes de temps-fréquenceFinalement, la discussion sera orientée selon trois axes : les méthodes de temps-fréquence ainsi qu'une proposition de traitement de ces données par une méthode statistique indépendante de la référence. La discussion du premier article en montrera la qualité du traitement de ces stimuli. La discussion des deux articles neurophysiologiques, proposera de nouvelles d'expériences afin d'affiner les résultats actuels sur les déficits des schizophrènes. Ceci pourrait permettre d'établir un marqueur biologique fiable de la schizophrénie.ABSTRACT (ENGLISH)This thesis focuses on the visual system in healthy subjects and schizophrenic patients. To address this research, advanced methods of analysis of electroencephalographic (EEG) data were used and developed. This manuscript is comprised of three scientific articles. The first article showed a novel method to control the physical features of visual stimuli (luminance and spatial frequencies). The second article showed, using electrical neuroimaging of EEG, a deficit in spatial processing associated with the dorsal pathway in chronic schizophrenic patients. This deficit was elicited by an absent modulation of the PI component in terms of response strength and topography as well as source estimations. This deficit was orthogonal to the preserved ability to process Kanizsa-type illusory contours. Finally, the third article resolved ongoing debates concerning the neural mechanism mediating illusory contour sensitivity by using electrical neuroimaging to show that the first differentiation of illusory contour presence vs. absence is localized within the lateral occipital complex. This effect was subsequent to modulations due to the orientation of misaligned grating stimuli. Collectively, these results support a model where effects in V1/V2 are mediated by "top-down" modulation from the LOC.To understand these three articles, the Introduction of this thesis presents the major concepts used in these articles. Additionally, a section is devoted to time-frequency analysis methods not presented in the articles themselves. The introduction is divided in four parts. The first part presents three aspects of the visual system: cellular, regional, and its functional interactions. The second part presents an overview of schizophrenia and its sensoiy-cognitive deficits. The third part presents an overview of illusory contour processing and the three models examined in the third article. Finally, advanced analysis methods for EEG are presented, including time- frequency methodology.The Introduction is followed by a synopsis of the main results in the articles as well as those obtained from the time-frequency analyses.Finally, the Discussion chapter is divided along three axes. The first axis discusses the time frequency analysis and proposes a novel statistical approach that is independent of the reference. The second axis contextualizes the first article and discusses the quality of the stimulus control and direction for further improvements. Finally, both neurophysiologic articles are contextualized by proposing future experiments and hypotheses that may serve to improve our understanding of schizophrenia on the one hand and visual functions more generally.

Epidermal growth factor and bovine growth hormone stimulate differentiation and myelination of brain cell aggregates in culture.

Bovine growth hormone (bGH) and epidermal growth factor (EGF) increased the activity of ornithine decarboxylase (ODC) in brain cell aggregates cultured in a serum-free chemically defined medium. ODC is considered as a marker of cell growth and differentiation. The effect of bGH and EGF on myelination was investigated by measuring two myelin markers, 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP) and myelin basic protein (MBP). EGF treatment at days 2 and 5 caused a dose-dependent increase of both myelin markers at culture day 12. This increase could still be observed at culture day 19, indicating a prolonged action of EGF. The continual presence of bGH in the culture medium produced a large accumulation of MBP at day 19. This effect was dose-dependent and required the presence of triiodothyronine (T3). In contrast, the effect of bGH on CNP activity did not require the presence of T3. This is the first report showing a direct effect of bGH on CNS myelination in vitro and of EGF on both MBP accumulation and ODC activity.

Increased plasma levels of N-terminal brain natriuretic peptide (NT-proBNP) in type 2 diabetic patients with vascular complications

Résumé : Les concentrations plasmatiques du peptide natriurétique de type B sont augmentées chez les diabétiques de type 2 atteints de complications vasculaires. But : Les concentrations plasmatiques du peptide natriurétique de type B (NT-proBNP) sont augmentées chez les diabétiques de type 2 atteints de complications vasculaires. Les concentrations plasmatiques du peptide natriurétique de type B (BNP), ou de sa pro-hormone (NT-proBNP), sont reconnues depuis peu comme marqueur de choix de la dysfonction cardiaque. Les diabétiques de type 2 sont à haut risque de développer des complications cardiovasculaires. L'objectif de cette étude a été de déterminer si les concentrations plasmatiques de NT-proBNP étaient comparables chez des diabétiques de type 2 avec ou sans complications vasculaires. Méthodes : Nous avons mesuré le NT-proBNP plasmatique chez 54 diabétiques de type 2, 27 sans complications micro- ou macrovasculaires et 27 présentant des complications soit micro- soit macrovasculaires, soit les deux. Le même dosage a été effectué chez 38 témoins sains, appariés pour l'âge et le sexe avec les diabétiques. Résultat : Le NT-proBNP plasmatique était plus élevé chez les diabétiques avec complications (médiane 121 pg/ml, intervalle interquartile 50-240 pg/ml) que chez ceux sans complications (37 pg/ml, 21-54 pg/ml, P < 0,01). Comparés au groupe témoin (55 pg/ml, 40-79 pg/ml), seuls les diabétiques avec complications vasculaires avaient un NT-proBNP plasmatique significativement augmenté (P < 0,001). Chez les diabétiques la maladie coronarienne et la néphropathie (définie selon l'excrétion urinaire d'albumine) étaient chacune associée de façon indépendante avec une augmentation des concentrations plasmatiques de NT-proBNP. Conclusion : Chez les diabétiques de type 2 souffrant de complications micro- ou macrovasculaires, les concentrations plasmatiques de NT-proBNP sont augmentées par rapport à celles des malades indemnes de complications vasculaires. L'augmentation de sécrétion de ce peptide est associée de façon indépendante avec la maladie coronarienne et la néphropathie. La mesure du NT-proBNP plasmatique pourrait donc être utile pour dépister la présence de complications micro- ou macrovasculaires.

On the origin of the MR image phase contrast: an in vivo MR microscopy study of the rat brain at 14.1 T.

Recent studies at high magnetic fields using the phase of gradient-echo MR images have shown the ability to unveil cortical substructure in the human brain. To investigate the contrast mechanisms in phase imaging, this study extends, for the first time, phase imaging to the rodent brain. Using a 14.1 T horizontal bore animal MRI scanner for in vivo micro-imaging, images with an in-plane resolution of 33 microm were acquired. Phase images revealed, often more clearly than the corresponding magnitude images, hippocampal fields, cortical layers (e.g. layer 4), cerebellar layers (molecular and granule cell layers) and small white matter structures present in the striatum and septal nucleus. The contrast of the phase images depended in part on the orientation of anatomical structures relative to the magnetic field, consistent with bulk susceptibility variations between tissues. This was found not only for vessels, but also for white matter structures, such as the anterior commissure, and cortical layers in the cerebellum. Such susceptibility changes could result from variable blood volume. However, when the deoxyhemoglobin content was reduced by increasing cerebral blood flow (CBF) with a carbogen breathing challenge, contrast between white and gray matter and cortical layers was not affected, suggesting that tissue cerebral blood volume (and therefore deoxyhemoglobin) is not a major source of the tissue phase contrast. We conclude that phase variations in gradient-echo images are likely due to susceptibility shifts of non-vascular origin.

Can GAP-43 interact with brain spectrin?

The growth-associated and presynaptic protein GAP-43 is important for axonal growth during brain development, for synaptic plasticity and in axonal regeneration [Benowitz, Routtenberg, TINS 12 (1987) 527]. It has been speculated that such growth may be mediated by cytoskeletal proteins. However, the interaction of GAP-43 with proteins of the presynaptic terminals is poorly characterized. Here, we analyze GAP-43 binding to cytoskeletal proteins by two different biochemical assays, by blot overlay and sedimentation. We find that immobilized brain spectrin (BS) is able to bind GAP-43. In contrast, little binding was observed to microtubule proteins and other elements of the cytoskeleton. Since GAP-43 is located presynaptically, it may bind to the presynaptic form of BS (SpIISigma1). It is attractive to think that such an interaction would participate in the structural plasticity observed in growth cones and adult synapses.

Epidermal growth factor (EGF) stimulation of cultured brain cells. II. Increased production of extracellular soluble proteins.

The production of extracellular soluble proteins was studied in serum-free aggregating cell cultures of fetal rat telencephalon labeled on culture day 7 with a mixture of radioactive amino acid precursors. Cultures treated continuously with epidermal growth factor (EGF; 20 ng/ml) showed a generally increased protein secretion and a particularly enhanced production of a few distinct extracellular proteins. The time lag of this response after an initial dose of EGF (25 ng/ml) on day 7 was 48 h. The total macromolecular radioactivity that accumulated within 96 h of labeling in the media of EGF-treated cultures was 175% of untreated controls, whereas no difference was found in the proportions of intracellular amino acid incorporation. Cultures which received a single dose of EGF (25 ng/ml) on day 1 showed still a greatly increased protein secretion on day 7. Prevention of extracellular protein accumulation by reducing the initial cell number and increasing the rate of media changes did not affect the EGF-induced stimulation of the two glial enzymes, glutamine synthetase and 2',3'-cyclic nucleotide 3'-phosphohydrolase. The results suggest that both the increased production of extracellular proteins and the enhanced development of glial enzymatic activities reflect the stimulated phenotypic expression of EGF-sensitive brain cells.

Transcranial Doppler after traumatic brain injury: is there a role?

PURPOSE OF REVIEW: To present the practical aspects of transcranial Doppler (TCD) and provide evidence supporting its use for the management of traumatic brain injury (TBI) patients. RECENT FINDINGS: TCD measures systolic, mean, and diastolic cerebral blood flow (CBF) velocities and calculates the pulsatility index from basal intracranial arteries. These variables reflect the brain circulation, provided there is control of potential confounding factors. TCD can be useful in patients with severe TBI to detect low CBF, for example, during intracranial hypertension, and to assess cerebral autoregulation. In the emergency room, TCD might complement brain computed tomography (CT) scan and clinical examination to screen patients at risk for further neurological deterioration after mild-to-moderate TBI. SUMMARY: The diagnostic value of TCD should be incorporated into other findings from multimodal brain monitoring and CT scan to optimize the bedside management of patients with TBI and help guide the choice of appropriate therapies.

Brain natriuretic peptide is able to stimulate cardiac progenitor cell proliferation and differentiation in murine hearts after birth.

Brain natriuretic peptide (BNP) contributes to heart formation during embryogenesis. After birth, despite a high number of studies aimed at understanding by which mechanism(s) BNP reduces myocardial ischemic injury in animal models, the actual role of this peptide in the heart remains elusive. In this study, we asked whether BNP treatment could modulate the proliferation of endogenous cardiac progenitor cells (CPCs) and/or their differentiation into cardiomyocytes. CPCs expressed the NPR-A and NPR-B receptors in neonatal and adult hearts, suggesting their ability to respond to BNP stimulation. BNP injection into neonatal and adult unmanipulated mice increased the number of newly formed cardiomyocytes (neonatal: +23 %, p = 0.009 and adult: +68 %, p = 0.0005) and the number of proliferating CPCs (neonatal: +142 %, p = 0.002 and adult: +134 %, p = 0.04). In vitro, BNP stimulated CPC proliferation via NPR-A and CPC differentiation into cardiomyocytes via NPR-B. Finally, as BNP might be used as a therapeutic agent, we injected BNP into mice undergoing myocardial infarction. In pathological conditions, BNP treatment was cardioprotective by increasing heart contractility and reducing cardiac remodelling. At the cellular level, BNP stimulates CPC proliferation in the non-infarcted area of the infarcted hearts. In the infarcted area, BNP modulates the fate of the endogenous CPCs but also of the infiltrating CD45(+) cells. These results support for the first time a key role for BNP in controlling the progenitor cell proliferation and differentiation after birth. The administration of BNP might, therefore, be a useful component of therapeutic approaches aimed at inducing heart regeneration.