The pressure cooker technique for the treatment of brain AVMs.

Arteriovenous malformations (AVMs) may be cured by injecting liquid embolic agents such as Onyx. Reflux, however, can sometimes be difficult to control and may jeopardize a complete embolization. The pressure cooker technique (PCT) was designed to create an anti-reflux plug by trapping the detachable part of an Onyx-compatible microcatheter with coils and glue in order to obtain wedge-flow conditions, thereby enabling a better understanding of macrofistulous AVMs and a more comprehensive, forceful and controlled Onyx embolization. The PCT might enlarge the range of AVMs amenable to endovascular cure. Three illustrative cases are presented.

MDCT Arthrography of the Hip: Value of the Adaptive Statistical Iterative Reconstruction Technique and Potential for Radiation Dose Reduction

Au cours des deux dernières décennies, la technique d'imagerie arthro-scanner a bénéficié de nombreux progrès technologiques et représente aujourd'hui une excellente alternative à l'imagerie par résonance magnétique (IRM) et / ou arthro-IRM dans l'évaluation des pathologies de la hanche. Cependant, elle reste limitée par l'exposition aux rayonnements ionisants importante. Les techniques de reconstruction itérative (IR) ont récemment été mis en oeuvre avec succès en imagerie ; la littérature montre que l'utilisation ces dernières contribue à réduire la dose d'environ 40 à 55%, comparativement aux protocoles courants utilisant la rétroprojection filtrée (FBP), en scanner de rachis. A notre connaissance, l'utilisation de techniques IR en arthro-scanner de hanche n'a pas été évaluée jusqu'à présent. Le but de notre étude était d'évaluer l'impact de la technique ASIR (GE Healthcare) sur la qualité de l'image objective et subjective en arthro-scanner de hanche, et d'évaluer son potentiel en terme de réduction de dose. Pour cela, trente sept patients examinés par arthro-scanner de hanche ont été randomisés en trois groupes : dose standard (CTDIvol = 38,4 mGy) et deux groupes de dose réduite (CTDIvol = 24,6 ou 15,4 mGy). Les images ont été reconstruites en rétroprojection filtrée (FBP) puis en appliquant différents pourcentages croissants d'ASIR (30, 50, 70 et 90%). Le bruit et le rapport contraste sur bruit (CNR) ont été mesurés. Deux radiologues spécialisés en imagerie musculo-squelettique ont évalué de manière indépendante la qualité de l'image au niveau de plusieurs structures anatomiques en utilisant une échelle de quatre grades. Ils ont également évalué les lésions labrales et du cartilage articulaire. Les résultats révèlent que le bruit augmente (p = 0,0009) et le CNR diminue (p = 0,001) de manière significative lorsque la dose diminue. A l'inverse, le bruit diminue (p = 0,0001) et le contraste sur bruit augmente (p < 0,003) de manière significative lorsque le pourcentage d'ASIR augmente ; on trouve également une augmentation significative des scores de la qualité de l'image pour le labrum, le cartilage, l'os sous-chondral, la qualité de l'image globale (au delà de ASIR 50%), ainsi que le bruit (p < 0,04), et une réduction significative pour l'os trabuculaire et les muscles (p < 0,03). Indépendamment du niveau de dose, il n'y a pas de différence significative pour la détection et la caractérisation des lésions labrales (n=24, p = 1) et des lésions cartilagineuses (n=40, p > 0,89) en fonction du pourcentage d'ASIR. Notre travail a permis de montrer que l'utilisation de plus de 50% d'ASIR permet de reduire de manière significative la dose d'irradiation reçue par le patient lors d'un arthro-scanner de hanche tout en maintenant une qualité d'image diagnostique comparable par rapport à un protocole de dose standard utilisant la rétroprojection filtrée.

Ross procedure: is the root replacement technique superior to the sub-coronary implantation technique? Long-term results.

There is controversy over the use of the Ross procedure with regard to the sub-coronary and root replacement technique and its long-term durability. A systematic review of the literature may provide insight into the outcomes of these two surgical subvariants. A systematic review of reports between 1967 and February 2013 on sub-coronary and root replacement Ross procedures was undertaken. Twenty-four articles were included and divided into (i) sub-coronary technique and (ii) root replacement technique. The 10-year survival rate for a mixed-patient population in the sub-coronary procedure was 87.3% with a 95% confidence interval (CI) of 79.7-93.4 and 89.1% (95% CI, 85.3-92.1) in the root replacement technique category. For adults, it was 94 vs 95.3% (CI, 88.9-98.1) and in the paediatric series it was 90 vs 92.7% (CI, 86.9-96.0), respectively. Freedom from reoperation at 10 years was, in the mixed population, 83.3% (95% CI, 69.9-93.4) and 93.3% (95% CI, 89.4-95.9) for sub-coronary versus root replacement technique, respectively. In adults, it was 98 vs 91.2% (95% CI, 82.4-295.8), and in the paediatric series 93.3 vs 92.0% (95% CI, 86.1-96.5) for sub-coronary versus root replacement technique, respectively. The Ross procedure arguably has satisfactory results over 5 and 10 years for both adults and children. The results do not support the advantages of the sub-coronary technique over the root replacement technique. Root replacement was of benefit to patients undergoing reoperations on neoaorta and for long-term survival in mixed series.

Genetics of calcium homeostasis in humans: continuum between monogenic diseases and continuous phenotypes

Extracellular calcium participates in several key physiological functions, such as control of blood coagulation, bone calcification or muscle contraction. Calcium homeostasis in humans is regulated in part by genetic factors, as illustrated by rare monogenic diseases characterized by hypo or hypercalcaemia. Both serum calcium and urinary calcium excretion are heritable continuous traits in humans. Serum calcium levels are tightly regulated by two main hormonal systems, i.e. parathyroid hormone and vitamin D, which are themselves also influenced by genetic factors. Recent technological advances in molecular biology allow for the screening of the human genome at an unprecedented level of detail and using hypothesis-free approaches, such as genome-wide association studies (GWAS). GWAS identified novel loci for calcium-related phenotypes (i.e. serum calcium and 25-OH vitamin D) that shed new light on the biology of calcium in humans. The substantial overlap (i.e. CYP24A1, CASR, GATA3; CYP2R1) between genes involved in rare monogenic diseases and genes located within loci identified in GWAS suggests a genetic and phenotypic continuum between monogenic diseases of calcium homeostasis and slight disturbances of calcium homeostasis in the general population. Future studies using whole-exome and whole-genome sequencing will further advance our understanding of the genetic architecture of calcium homeostasis in humans. These findings will likely provide new insight into the complex mechanisms involved in calcium homeostasis and hopefully lead to novel preventive and therapeutic approaches. Keyword: calcium, monogenic, genome-wide association studies, genetics.

Block of the superior cervical ganglion, description of a novel ultrasound-guided technique in human cadavers.

OBJECTIVE.: Injection of opioids to the superior cervical ganglion (SCG) has been reported to provide pain relief in patients suffering from different kinds of neuropathic facial pain conditions, such as trigeminal neuralgia, postherpetic neuralgia, and atypical facial pain. The classic approach to the SCG is a transoral technique using a so-called "stopper" to prevent accidental carotid artery puncture. The main disadvantage of this technique is that the needle tip is positioned distant from the actual target, possibly impeding successful block of the SCG. A further limitation is that injection of local anesthetics due to potential carotid artery puncture is contraindicated. We hypothesized that the SCG can be identified and blocked using ultrasound imaging, potentially increasing precision of this technique. INTERVENTIONS.: In this pilot study, 20 US-guided simulated blocks of the SCG were performed in 10 human cadavers in order to determine the accuracy of this novel block technique. After injection of 0.1 mL of dye, the cadavers were dissected to evaluate the needle position and coloring of the SCG. RESULTS.: Nineteen of the 20 needle tips were located in or next to the SCG. This corresponded to a simulated block success rate of 95% (95% confidence interval 85-100%). In 17 cases, the SCG was completely colored, and in two cases, the caudal half of the SCG was colored with dye. CONCLUSIONS.: The anatomical dissections confirmed that our ultrasound-guided approach to the SCG is accurate. Ultrasound could become an attractive alternative to the "blind" transoral technique of SCG blocks.

Late removal of retrievable caval filters.

The advent of retrievable caval filters was a game changer in the sense, that the previously irreversible act of implanting a medical device into the main venous blood stream of the body requiring careful evaluation of the pros and cons prior to execution suddenly became a "reversible" procedure where potential hazards in the late future of the patient lost most of their weight at the time of decision making. This review was designed to assess the rate of success with late retrieval of so called retrievable caval filters in order to get some indication about reasonable implant duration with respect to relatively "easy" implant removal with conventional means, i.e., catheters, hooks and lassos. A PubMed search (www.pubmed.gov) was performed with the search term "cava filter retrieval after 30 days clinical", and 20 reports between 1994 and 2013 dealing with late retrieval of caval filters were identified, covering approximately 7,000 devices with 600 removed filters. The maximal duration of implant reported is 2,599 days and the maximal implant duration of removed filters is also 2,599 days. The maximal duration reported with standard retrieval techniques, i.e., catheter, hook and/or lasso, is 475 days, whereas for the retrievals after this period more sophisticated techniques including lasers, etc. were required. The maximal implant duration for series with 100% retrieval accounts for 84 days, which is equivalent to 12 weeks or almost 3 months. We conclude that retrievable caval filters often become permanent despite the initial decision of temporary use. However, such "forgotten" retrievable devices can still be removed with a great chance of success up to three months after implantation. Conventional percutaneous removal techniques may be sufficient up to sixteen months after implantation whereas more sophisticated catheter techniques have been shown to be successful up to 83 months or more than seven years of implant duration. Tilting, migrating, or misplaced devices should be removed early on, and replaced if indicated with a device which is both, efficient and retrievable.

Adenovirus-mediated gene transfer into selected liver segments using a vascular exclusion technique.

Adenovirus-mediated gene therapy is hampered by severe virus-related toxicity, especially to the liver. The aim of the present study was to test the ability of a vascular exclusion technique to achieve transgene expression within selected liver segments, thus minimizing both viral and transgene product toxicity to the liver. An E1-E3-deleted replication-deficient adenovirus expressing a green fluorescent protein (GFP) reporter gene was injected into the portal vein of BDIX rats, with simultaneous clamping of the portal vein tributaries to liver segments II, III, IV, V, and VIII. GFP expression and inflammatory infiltrate were measured in the different segments of the liver and compared with those of the livers of animals receiving the viral vector in the portal vein without clamping. The GFP expression was significantly higher in the selectively perfused segments of the liver as compared with the non-perfused segments (p < 0.0001) and with the livers of animals that received the vector in the portal vein without clamping (p < 0.0001). Accordingly, the inflammatory infiltrate was more intense in the selectively perfused liver segments as compared with all other groups (p < 0.0001). Fluorescence was absent in lungs and kidneys and minimal in spleen. The clinical usefulness of adenovirus-mediated gene transfer to the liver largely depends on the reduction of its liver toxicity. Clamping of selected portal vein branches during injection allows for delivery of genes of interest to targeted liver segments. Transgene expression confined to selected liver segments may be useful in the treatment of focal liver diseases, including metastases.

Biogeochemical evolution of a marine shore tailings deposit during bioremediation

Summary : Mining activities produce enormous amounts of waste material known as tailings which are composed of fine to medium size particles. These tailings often contain sulfides, which oxidation can lead to acid and metal contamination of water; therefore they need to be remediated. In this work a tailings bioremediation approach was investigated by an interdisciplinary study including geochemistry, mineralogy and microbiology. The aim of the work was to study the effect of the implementation of wetland above oxidizing tailings on the hydrogeology and the biogeochemical element cycles, and to assess the system evolution over time. To reach these goals, biogeochemical processes occurring in a marine shore tailings deposit were investigated. The studied tailings deposit is located at the Bahìa de Ite, Pacific Ocean, southern Peru, where between 1940 and 1996 the tailings were discharged from the two porphyry copper mines Cuajone and Toquepala. After the end of deposition, a remediation approach was initiated in 1997 with a wetland implementation above the oxidizing tailings. Around 90% of the tailings deposits (total 16 km2) were thus remediated, except the central delta area and some areas close to the shoreline. The multi-stable isotope study showed that the tailings were saturated with fresh water in spite of the marine setting, due to the high hydraulic gradient resulting from the wetland implementation. Submarine groundwater discharge (SGD) was the major source of SO4 2-, C1-, Na+, Fe2+, and Mn2+ input into the tailings at the original shelf-seawater interface. The geochemical study (aquatic geochemistry and X-Ray diffraction (XRD) and sequential extractions from the solid fraction) showed that iron and sulfur oxidation were the main processes in the non-remediated tailings, which showed a top a low-pH oxidation zone with strong accumulation of efflorescent salts at the surface due to capillary upward transport of heavy metals (Fe, Cu, Zn, Mn, Cd, Co, and Ni) in the arid climate. The study showed also that the implementation of the wetland resulted in very low concentrations of heavy metals in solution (mainly under the detection limit) due to the near neutral pH and more reducing conditions (100-150 mV). The heavy metals, which were taken from solution, precipitated as hydroxides and sulfides or were bound to organic matter. The bacterial community composition analysis by Terminal Restriction Fragment Length Polymorphism (T-RFLP) and cloning and sequencing of 16S rRNA genes combined with a detailed statistical analysis revealed a high correlation between the bacterial distribution and the geochemical variables. Acidophilic autotrophic oxidizing bacteria were dominating the oxidizing tailings, whereas neutrophilic and heterotrophic reducing bacteria were driving the biogeochemical processes in the remediated tailings below the wetland. At the subsurface of the remediated tailings, an iron cycling was highlighted with oxidation and reduction processes due to micro-aerophilic niches provided by the plant rhizosphere in this overall reducing environment. The in situ bioremediation experiment showed that the main parameter to take into account for the effectiveness was the water table and chemistry which controls the system. The constructed remediation cells were more efficient and rapid in metal removal when saturation conditions were available. This study showed that the bioremediation by wetland implementation could be an effective and rapid treatment for some sulfidic mine tailings deposits. However, the water saturation of the tailings has to be managed on a long-term basis in order to guarantee stability. Résumé : L'activité minière produit d'énormes quantités de déchets géologiques connus sous le nom de « tailings » composées de particules de taille fine à moyenne. Ces déchets contiennent souvent des sulfures dont l'oxydation conduit à la formation d'effluents acides contaminés en métaux, d'où la nécessité d'effectuer une remédiation des sites de stockage concernés. Le but de ce travail est dans un premier temps d'étudier l'effet de la bio-remédiation d'un dépôt de tailings oxydés sur l'hydrogéologie du système et les cycles biogéochimiques des éléments et en second lieu, d'évaluer l'évolution du processus de remédiation dans le temps. Le site étudié dans ce travail est situé dans la Bahía de Ite, au sud du Pérou, au bord de l'Océan Pacifique. Les déchets miniers en question sont déposés dans un environnement marin. De 1940 à 1996, les déchets de deux mines de porphyre cuprifère - Cuajone et Toquepala - ont été acheminés sur le site via la rivière Locumba. En 1997, une première remédiation a été initiée avec la construction d'une zone humide sur les tailings. Depuis, environ 90% de la surface du dépôt (16 km2) a été traité, les parties restantes étant la zone centrale du delta du Locumba et certaines zones proches de la plage. Malgré la proximité de l'océan, les études isotopiques menées dans le cadre de ce travail ont montré que les tailings étaient saturés en eau douce. Cette saturation est due à la pression hydraulique résultant de la mise en place des zones humides. Un écoulement d'eau souterrain sous-marin a été à détecté à l'interface entre les résidus et l'ancien fond marin. En raison de la géologie locale, il constitue une source d'entrée de SO4 2-, Cl-, Na+, FeZ+, et Mn2+ dans le système. L'analyse de la géochimie aquatique, la Diffraction aux Rayons X (XRD) et l'extraction séquentielle ont montré que l'oxydation du fer et .des sulfures est le principal processus se produisant dans les déchets non remédiés. Ceci a entraîné le développement d'une zone d'oxydation à pH bas induisant une forte accumulation des sels efflorescents, conséquence de la migration capillaire des métaux lourds (Fe, Cu, Zn, Mn, Cd, Co et Ni) de la solution vers la surface dans ce climat aride. Cette étude a montré également que la construction de la zone humide a eu comme résultats une précipitation des métaux dans des phases minérales en raison du pH neutre et des conditions réductrices (100-150mV). Les métaux lourds ont précipité sous la forme d'hydroxydes et de sulfures ou sont adsorbés à la matière organique. L'analyse de la composition de la communauté bactérienne à l'aide la technique T-RFLP (Terminal Restriction Fragment Length Polymorphism) et par le clonage/séquençage des gènes de l'ARNr 16S a été combinée à une statistique détaillée. Cette dernière a révélé une forte corrélation entre la distribution de bactéries spécifiques et la géochimie : Les bactéries autotrophes acidophiles dominent dans les déchets oxydés non remédiés, tandis que des bactéries hétérotrophes neutrophiles ont mené les processus microbiens dans les déchets remédiés sous la zone humide. Sous la surface de la zone humide, nos analyses ont également mis en évidence un cycle du fer par des processus d'oxydoréduction rendus possibles par la présence de niches micro-aérées par la rhizosphère dans cet environnement réducteur. L'expérience de bio-remédiation in situ a montré que les paramètres clés qui contrôlent l'efficacité du traitement sont le niveau de la nappe aquifère et la chimie de l'eau. Les cellules de remédiation se sont montrées plus efficaces et plus rapides lorsque le système a pu être saturé en eau. Finalement, cette étude a montré que la bio-remédiation de déchets miniers par la construction de zones humides est un moyen de traitement efficace, rapide et peu coûteux. Cependant, la saturation en eau du système doit être gérée sur le long terme afin de garantir la stabilité de l'ensemble du système.

A new technique to measure micromotion distribution around a cementless femoral stem.

The interfacial micromotion is closely associated to the long-term success of cementless hip prostheses. Various techniques have been proposed to measure them, but only a few number of points over the stem surface can be measured simultaneously. In this paper, we propose a new technique based on micro-Computer Tomography (μCT) to measure locally the relative interfacial micromotions between the metallic stem and the surrounding femoral bone. Tantalum beads were stuck at the stem surface and spread at the endosteal surface. Relative micromotions between the stem and the endosteal bone surfaces were measured at different loading amplitudes. The estimated error was 10μm and the maximal micromotion was 60μm, in the loading direction, at 1400N. This pilot study provided a local measurement of the micromotions in the 3 direction and at 8 locations on the stem surface simultaneously. This technique could be easily extended to higher loads and a much larger number of points, covering the entire stem surface and providing a quasi-continuous distribution of the 3D interfacial micromotions around the stem. The new measurement method would be very useful to compare the induced micromotions of different stem designs and to optimize the primary stability of cementless total hip arthroplasty.