Techniques de "non-fusion" en chirurgie rachidienne [Non fusion techniques in spinal surgery]

In order to prevent adjacent segment degeneration following spinal fusion new techniques are being used. Lumbar disc arthroplasty yields mid term results equivalent to those of spinal fusion. Cervical disc arthroplasty is indicated in the treatment of cervicobrachialgia with encouraging initial results. The ability of arthroplasty to prevent adjacent segment degeneration has yet to be proven. Although dynamic stabilization had not been proven effective in treating chronic low back pain, it might be useful following decompression of lumbar spinal stenosis in degenerative spondylolisthesis. Interspinal devices are useful in mild lumbar spinal stenosis but their efficacy in treating low back pain is yet to be proven. Confronted with a growing number of new technologies clinicians should remain critical while awaiting long term results.

Glut2-dependent glucose-sensing controls thermoregulation by enhancing the leptin sensitivity of NPY and POMC neurons.

The physiological contribution of glucose in thermoregulation is not completely established nor whether this control may involve a regulation of the melanocortin pathway. Here, we assessed thermoregulation and leptin sensitivity of hypothalamic arcuate neurons in mice with inactivation of glucose transporter type 2 (Glut2)-dependent glucose sensing. Mice with inactivation of Glut2-dependent glucose sensors are cold intolerant and show increased susceptibility to food deprivation-induced torpor and abnormal hypothermic response to intracerebroventricular administration of 2-deoxy-d-glucose compared to control mice. This is associated with a defect in regulated expression of brown adipose tissue uncoupling protein I and iodothyronine deiodinase II and with a decreased leptin sensitivity of neuropeptide Y (NPY) and proopiomelanocortin (POMC) neurons, as observed during the unfed-to-refed transition or following i.p. leptin injection. Sites of central Glut-2 expression were identified by a genetic tagging approach and revealed that glucose-sensitive neurons were present in the lateral hypothalamus, the dorsal vagal complex, and the basal medulla but not in the arcuate nucleus. NPY and POMC neurons were, however, connected to nerve terminals from Glut2-expressing neurons. Thus, our data suggest that glucose controls thermoregulation and the leptin sensitivity of NPY and POMC neurons through activation of Glut2-dependent glucose-sensing neurons located outside of the arcuate nucleus.

Fc block treatment, dead cells exclusion, and cell aggregates discrimination concur to prevent phenotypical artifacts in the analysis of subpopulations of tumor-infiltrating CD11b(+) myelomonocytic cells.

It is well established that cancer cells can recruit CD11b(+) myeloid cells to promote tumor angiogenesis and tumor growth. Increasing interest has emerged on the identification of subpopulations of tumor-infiltrating CD11b(+) myeloid cells using flow cytometry techniques. In the literature, however, discrepancies exist on the phenotype of these cells (Coffelt et al., Am J Pathol 2010;176:1564-1576). Since flow cytometry analysis requires particular precautions for accurate sample preparation and trustable data acquisition, analysis, and interpretation, some discrepancies might be due to technical reasons rather than biological grounds. We used the syngenic orthotopic 4T1 mammary tumor model in immunocompetent BALB/c mice to analyze and compare the phenotype of CD11b(+) myeloid cells isolated from peripheral blood and from tumors, using six-color flow cytometry. We report here that the nonspecific antibody binding through Fc receptors, the presence of dead cells and cell doublets in tumor-derived samples concur to generate artifacts in the phenotype of tumor-infiltrating CD11b(+) subpopulations. We show that the heterogeneity of tumor-infiltrating CD11b(+) subpopulations analyzed without particular precautions was greatly reduced upon Fc block treatment, dead cells, and cell doublets exclusion. Phenotyping of tumor-infiltrating CD11b(+) cells was particularly sensitive to these parameters compared to circulating CD11b(+) cells. Taken together, our results identify Fc block treatment, dead cells, and cell doublets exclusion as simple but crucial steps for the proper analysis of tumor-infiltrating CD11b(+) cell populations.

Evolving techniques to evaluate ejaculatory function.

PURPOSE OF REVIEW: Recent findings in the physiology and neurobiology of ejaculation have expanded our understanding of male sexual function and have allowed the development of new instruments to investigate ejaculatory and orgasmic disorders. RECENT FINDINGS: The evidence-based definition of lifelong premature ejaculation has set a model in the evaluation and treatment outcome of sexual dysfunction. New instruments to objectively assess arousal, orgasm and the expulsion phase of ejaculation such as functional MRI, dynamic pelvic ultrasound, PET scans and validated questionnaires have lead to a better understanding of sexual dysfunction in men. Animal models, developments in neurobiology and clinical experience have transformed a purely psychoanalytical approach to ejaculatory and orgasmic function into a novel multidisciplinary, scientifically sound and evidence-based discipline of medicine. SUMMARY: Ejaculation is an integral part of normal sexual function. Ejaculatory dysfunction is common and may cause substantial disruption to the quality of a patient's life. A better understanding of the epidemiology, pathophysiology, neuroscience and genetics of ejaculatory and orgasmic function will eventually lead to the development of new, effective methods of treatment of disorders of ejaculation and orgasm in men.

Rapid detection of bacterial resistance to antibiotics using AFM cantilevers as nanomechanical sensors.

The widespread misuse of drugs has increased the number of multiresistant bacteria, and this means that tools that can rapidly detect and characterize bacterial response to antibiotics are much needed in the management of infections. Various techniques, such as the resazurin-reduction assays, the mycobacterial growth indicator tube or polymerase chain reaction-based methods, have been used to investigate bacterial metabolism and its response to drugs. However, many are relatively expensive or unable to distinguish between living and dead bacteria. Here we show that the fluctuations of highly sensitive atomic force microscope cantilevers can be used to detect low concentrations of bacteria, characterize their metabolism and quantitatively screen (within minutes) their response to antibiotics. We applied this methodology to Escherichia coli and Staphylococcus aureus, showing that live bacteria produced larger cantilever fluctuations than bacteria exposed to antibiotics. Our preliminary experiments suggest that the fluctuation is associated with bacterial metabolism.

Buprenorphine and norbuprenorphine quantification in human plasma by simple protein precipitation and ultra-high performance liquid chromatography tandem mass spectrometry.

A highly sensitive ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method was developed for the quantification of buprenorphine and its major metabolite norbuprenorphine in human plasma. In order to speed up the process and decrease costs, sample preparation was performed by simple protein precipitation with acetonitrile. To the best of our knowledge, this is the first application of this extraction technique for the quantification of buprenorphine in plasma. Matrix effects were strongly reduced and selectivity increased by using an efficient chromatographic separation on a sub-2μm column (Acquity UPLC BEH C18 1.7μm, 2.1×50mm) in 5min with a gradient of ammonium formate 20mM pH 3.05 and acetonitrile as mobile phase at a flow rate of 0.4ml/min. Detection was made using a tandem quadrupole mass spectrometer operating in positive electrospray ionization mode, using multiple reaction monitoring. The procedure was fully validated according to the latest Food and Drug Administration guidelines and the Société Française des Sciences et Techniques Pharmaceutiques. Very good results were obtained by using a stable isotope-labeled internal standard for each analyte, to compensate for the variability due to the extraction and ionization steps. The method was very sensitive with lower limits of quantification of 0.1ng/ml for buprenorphine and 0.25ng/ml for norbuprenorphine. The upper limit of quantification was 250ng/ml for both drugs. Trueness (98.4-113.7%), repeatability (1.9-7.7%), intermediate precision (2.6-7.9%) and internal standard-normalized matrix effects (94-101%) were in accordance with international recommendations. The procedure was successfully used to quantify plasma samples from patients included in a clinical pharmacogenetic study and can be transferred for routine therapeutic drug monitoring in clinical laboratories without further development.

Comparing potentially avoidable hospitalization rates related to ambulatory care sensitive conditions in Switzerland: the need to refine the definition of health conditions and to adjust for population health status.

BACKGROUND: Regional rates of hospitalization for ambulatory care sensitive conditions (ACSC) are used to compare the availability and quality of ambulatory care but the risk adjustment for population health status is often minimal. The objectives of the study was to examine the impact of more extensive risk adjustment on regional comparisons and to investigate the relationship between various area-level factors and the properly adjusted rates. METHODS: Our study is an observational study based on routine data of 2 million anonymous insured in 26 Swiss cantons followed over one or two years. A binomial negative regression was modeled with increasingly detailed information on health status (age and gender only, inpatient diagnoses, outpatient conditions inferred from dispensed drugs and frequency of physician visits). Hospitalizations for ACSC were identified from principal diagnoses detecting 19 conditions, with an updated list of ICD-10 diagnostic codes. Co-morbidities and surgical procedures were used as exclusion criteria to improve the specificity of the detection of potentially avoidable hospitalizations. The impact of the adjustment approaches was measured by changes in the standardized ratios calculated with and without other data besides age and gender. RESULTS: 25% of cases identified by inpatient main diagnoses were removed by applying exclusion criteria. Cantonal ACSC hospitalizations rates varied from to 1.4 to 8.9 per 1,000 insured, per year. Morbidity inferred from diagnoses and drugs dramatically increased the predictive performance, the greatest effect found for conditions linked to an ACSC. More visits were associated with fewer PAH although very high users were at greater risk and subjects who had not consulted at negligible risk. By maximizing health status adjustment, two thirds of the cantons changed their adjusted ratio by more than 10 percent. Cantonal variations remained substantial but unexplained by supply or demand. CONCLUSION: Additional adjustment for health status is required when using ACSC to monitor ambulatory care. Drug-inferred morbidities are a promising approach.

Multimodal MRI analysis of structural and functional networks in the human brain : application to two clinical studies : driving abilities under THC intoxication and early white matter changes in FXTAS

Les approches multimodales dans l'imagerie cérébrale non invasive sont de plus en plus considérées comme un outil indispensable pour la compréhension des différents aspects de la structure et de la fonction cérébrale. Grâce aux progrès des techniques d'acquisition des images de Resonance Magnetique et aux nouveaux outils pour le traitement des données, il est désormais possible de mesurer plusieurs paramètres sensibles aux différentes caractéristiques des tissues cérébraux. Ces progrès permettent, par exemple, d'étudier les substrats anatomiques qui sont à la base des processus cognitifs ou de discerner au niveau purement structurel les phénomènes dégénératifs et développementaux. Cette thèse met en évidence l'importance de l'utilisation d'une approche multimodale pour étudier les différents aspects de la dynamique cérébrale grâce à l'application de cette approche à deux études cliniques: l'évaluation structurelle et fonctionnelle des effets aigus du cannabis fumé chez des consommateurs réguliers et occasionnels, et l'évaluation de l'intégrité de la substance grise et blanche chez des jeunes porteurs de la prémutations du gène FMR1 à risque de développer le FXTAS (Fragile-X Tremor Ataxia Syndrome). Nous avons montré que chez les fumeurs occasionnels de cannabis, même à faible concentration du principal composant psychoactif (THC) dans le sang, la performance lors d'une tâche visuo-motrice est fortement diminuée, et qu'il y a des changements dans l'activité des trois réseaux cérébraux impliqués dans les processus cognitifs: le réseau de saillance, le réseau du contrôle exécutif, et le réseau actif par défaut (Default Mode). Les sujets ne sont pas en mesure de saisir les saillances dans l'environnement et de focaliser leur attention sur la tâche. L'augmentation de la réponse hémodynamique dans le cortex cingulaire antérieur suggère une augmentation de l'activité introspective. Une investigation des ef¬fets au niveau cérébral d'une exposition prolongée au cannabis, montre des changements persistants de la substance grise dans les régions associées à la mémoire et au traitement des émotions. Le niveau d'atrophie dans ces structures corrèle avec la consommation de cannabis au cours des trois mois précédant l'étude. Dans la deuxième étude, nous démontrons des altérations structurelles des décennies avant l'apparition du syndrome FXTAS chez des sujets jeunes, asymptomatiques, et porteurs de la prémutation du gène FMR1. Les modifications trouvées peuvent être liées à deux mécanismes différents. Les altérations dans le réseau moteur du cervelet et dans la fimbria de l'hippocampe, suggèrent un effet développemental de la prémutation. Elles incluent aussi une atrophie de la substance grise du lobule VI du cervelet et l'altération des propriétés tissulaires de la substance blanche des projections afférentes correspondantes aux pédoncules cérébelleux moyens. Les lésions diffuses de la substance blanche cérébrale peu¬vent être un marquer précoce du développement de la maladie, car elles sont liées à un phénomène dégénératif qui précède l'apparition des symptômes du FXTAS. - Multimodal brain imaging is becoming a leading tool for understanding different aspects of brain structure and function. Thanks to the advances in Magnetic Resonance imaging (MRI) acquisition schemes and data processing techniques, it is now possible to measure different parameters sensitive to different tissue characteristics. This allows for example to investigate anatomical substrates underlying cognitive processing, or to disentangle, at a pure structural level degeneration and developmental processes. This thesis highlights the importance of using a multimodal approach for investigating different aspects of brain dynamics by applying this approach to two clinical studies: functional and structural assessment of the acute effects of cannabis smoking in regular and occasional users, and grey and white matter assessment in young FMR1 premutation carriers at risk of developing FXTAS. We demonstrate that in occasional smokers cannabis smoking, even at low concentration of the main psychoactive component (THC) in the blood, strongly decrease subjects' performance on a visuo-motor tracking task, and globally alters the activity of the three brain networks involved in cognitive processing: the Salience, the Control Executive, and the Default Mode networks. Subjects are unable to capture saliences in the environment and to orient attention to the task; the increase in Hemodynamic Response in the Anterior Cingulate Cortex suggests an increase in self-oriented mental activity. A further investigation on long term exposure to cannabis, shows a persistent grey matter modification in brain regions associated with memory and affective processing. The degree of atrophy in these structures also correlates with the estimation of drug use in the three months prior the participation to the study. In the second study we demonstrate structural changes in young asymptomatic premutation carriers decades before the onset of FXTAS that might be related to two different mechanisms. Alteration of the cerebellar motor network and of the hippocampal fimbria/ fornix, may reflect a potential neurodevelopmental effect of the premutation. These include grey matter atrophy in lobule VI and modification of white matter tissue property in the corresponding afferent projections through the Middle Cerebellar Peduncles. Diffuse hemispheric white matter lesions that seem to appear closer to the onset of FXTAS and be related to a neurodegenerative phenomenon may mark the imminent onset of FXTAS.

Techniques de gastrostomie chez l'enfant et expérience lausannoise avec le bouton de gastrostomie à ballonnet (Mic-Key)

Résumé : Ce travail comprend deux parties : La première partie a pour but de présenter une revue des techniques de gastrostomie chez l'enfant. La gastrostomie est, par définition, un tractus fistuleux entre l'estomac et la paroi abdominale. Le but de la gastrostomie est de permettre la décompression gastrique, la nutrition entérale et l'apport médicamenteux. Les indications et contre-indications à la confection et utilisation de la gastrostomie sont détaillées dans ce travail. Historiquement, les premières gastrostomies étaient d'origine accidentelle ou infectieuse (fistule gastro-cutanée), incompatibles avec la vie. Sedillot, en 1845 décrivit la première gastrostomie chirurgicale sans cathéter, qui avait comme désavantage la présence de fuites. Depuis, les techniques se sont multipliées en évoluant vers la continence et l'utilisation de cathéters. En 1979 Gauderer décrivit pour la première fois une technique percutanée, réalisée sur un enfant âgé de 5 mois. Cette technique est appelée « Percutaneous Endoscopic Gastrostomy » (PEG). Elle a ensuite été élargie à la population adulte. Actuellement, il existe une grande multiplicité de techniques par abord « laparotomique », laparoscopique ou percutanée (endoscopique ou radiologique). Ces techniques peuvent être combinées. Toutes ces techniques nécessitent la présence intermittente ou continue d'un dispositif, qui permet le maintient de la gastrostomie ouverte et évite les fuites gastriques. Ces dispositifs sont multiples; initialement il s'agissait de cathéters rigides (bois, métal, caoutchouc). Ensuite ils ont été fabriqués en silicone, ce qui les rend plus souples et mieux tolérés par le patient. Pour éviter leur dislocation, ils possèdent un système d'amarrage intra-gastrique tel que : un champignon (Bard®), un ballonnet (Foley®, Mic-Key®), ou une forme spiralée du cathéter (« pig-tail ») et possèdent un système d'amarrage extra-gastrique (« cross-bar »). En 1982, Gauderer créa le premier dispositif à fleur de peau : le bouton de gastrostomie (BG). Actuellement, il en existe deux types : à champignon (Bard®) et à ballonnet (Mic-Key®). Il existe plusieurs types de complications liées à la technique opératoire, à la prise en charge et au matériel utilisé. Une comparaison des différentes techniques, matériaux utilisés et coûts engendrés est détaillée dans ce travail. La deuxième partie de ce travail est dédiée aux BG et plus spécifiquement au BG à ballonnet (Mic-Key®). Nous présentons les différents boutons et les techniques spécifiques. Le BG est inséré soit dans une gastrostomie préformée, soit directement lors de la confection d'une gastrostomie par laparotomie, laparoscopie ou de façon percutanée. Les complications liées au BG sont rapportées. D'autres utilisations digestives ou urologiques sont décrites. Nous présentons ensuite notre expérience avec 513 BG à ballonnet (Mic-Key®) dans une revue de 73 enfants. La pose du BG est effectuée dans une gastrostomie préformée sans recours à une anesthésie générale. La technique choisie pour la confection de la gastrostomie dépend de la pathologie de base, de l'état général du patient, de la nécessité d'une opération concomitante et du risque anesthésique. Nous apportons des précisions sur le BG telles que la dimension en fonction de l'âge, la durée de vie, et les causes qui ont amené au changement du BG. Nos résultats sont comparés à ceux de la littérature. Sur la base de notre expérience et après avoir passé en revue la littérature spécialisée, nous proposons des recommandations sur le choix de la technique et le choix du matériel. Ce travail se termine avec une réflexion sur le devenir de la gastrostomie. Si le futur consiste à améliorer et innover les techniques et les matériaux, des protocoles destinés à la standardisation des techniques, à la sélection des patients et à l'enseignement des soins devraient s'en suivre. La prise en charge de l'enfant ne se limite pas à la sélection appropriée de la technique et des matériaux, mais il s'agit avant tout d'une approche multidisciplinaire. La collaboration entre le personnel soignant, la famille et l'enfant est essentielle pour que la prise en charge soit optimale et sans risques.