995 resultados para Deposition technique


Relevância:

20.00% 20.00%

Publicador:

Resumo:

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.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

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.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

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.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

OBJECTIVE: Transthoracic echocardiography (TTE) has been used clinically to disobstruct venous drainage cannula and to optimise placement of venous cannulae in the vena cava but it has never been used to evaluate performance capabilities. Also, little progress has been made in venous cannula design in order to optimise venous return to the heart lung machine. We designed a self-expandable Smartcanula (SC) and analysed its performance capability using echocardiography. METHODS: An epicardial echocardiography probe was placed over the SC or control cannula (CTRL) and a Doppler image was obtained. Mean (V(m)) and maximum (V(max)) velocities, flow and diameter were obtained. Also, pressure drop (DeltaP(CPB)) was obtained between the central venous pressure and inlet to venous reservoir. LDH and Free Hb were also compared in 30 patients. Comparison was made between the two groups using the student's t-test with statistical significance established when p<0.05. RESULTS: Age for the SC and CC groups were 61.6+/-17.6 years and 64.6+/-13.1 years, respectively. Weight was 70.3+/-11.6 kg and 72.8+/-14.4 kg, respectively. BSA was 1.80+/-0.2 m(2) and 1.82+/-0.2 m(2), respectively. CPB times were 114+/-53 min and 108+/-44 min, respectively. Cross-clamp time was 59+/-15 min and 76+/-29 min, respectively (p=NS). Free-Hb was 568+/-142 U/l versus 549+/-271 U/l post-CPB for the SC and CC, respectively (p=NS). LDH was 335+/-73 mg/l versus 354+/-116 mg/l for the SC and CC, respectively (p=NS). V(m) was 89+/-10 cm/s (SC) versus 63+/-3 cm/s (CC), V(max) was 139+/-23 cm/s (SC) versus 93+/-11 cm/s (CC) (both p<0.01). DeltaP(CPB) was 30+/-10 mmHg (SC) versus 43+/-13 mmHg (CC) (p<0.05). A Bland-Altman test showed good agreement between the two devices used concerning flow rate calculations between CPB and TTE (bias 300 ml+/-700 ml standard deviation). CONCLUSIONS: This novel Smartcanula design, due to its self-expanding principle, provides superior flow characteristics compared to classic two stage venous cannula used for adult CPB surgery. No detrimental effects were observed concerning blood damage. Echocardiography was effective in analysing venous cannula performance and velocity patterns.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

BACKGROUND: Vascular reconstructions are becoming challenging due to the comorbidity of the aging population and since the introduction of minimally invasive approaches. Many sutureless anastomosis devices have been designed to facilitate the cardiovascular surgeon's work and the vascular join (VJ) is one of these. We designed an animal study to assess its reliability and long-term efficacy. METHODS: VJ allows the construction of end-to-end and end-to-side anastomoses. It consists of two metallic crowns fixed to the extremity of the two conduits so that vessel edges are joined layer by layer. There is no foreign material exposed to blood. In adult sheep both carotid arteries were prepared and severed. End-to-end anastomoses were performed using the VJ device on one side and the classical running suture technique on the other side. Animals were followed-up with Duplex-scan every 3 months and sacrificed after 12 months. Histopathological analysis was carried out. RESULTS: In 20 animals all 22 sutureless anastomoses were successfully completed in less than 2 min versus 6 +/- 3 min for running suture. Duplex showed the occlusion of three controls and one sutureless anastomosis. Two controls and one sutureless had stenosis >50%. Histology showed very thin layer of myointimal hyperplasia (50 +/- 10 microm) in the sutureless group versus 300 +/- 27 microm in the control. No significant inflammatory reaction was detected. CONCLUSIONS: VJ provides edge-to-edge vascular repair that can be considered the most physiological way to restore vessel continuity. For the first time, in healthy sheep, an anastomotic device provided better results than suture technique.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

PURPOSE: To improve fat saturation in coronary MRA at 3T by using a spectrally selective adiabatic T2 -Prep (WSA-T2 -Prep). METHODS: A conventional adiabatic T2 -Prep (CA-T2 -Prep) was modified, such that the excitation and restoration pulses were of differing bandwidths. On-resonance spins are T2 -Prepared, whereas off-resonance spins, such as fat, are spoiled. This approach was combined with a CHEmically Selective Saturation (CHESS) pulse to achieve even greater fat suppression. Numerical simulations were followed by phantom validation and in vivo coronary MRA. RESULTS: Numerical simulations demonstrated that augmenting a CHESS pulse with a WSA-T2 -Prep improved robustness to B1 inhomogeneities and that this combined fat suppression was effective over a broader spectral range than that of a CHESS pulse in a conventional T2 -Prepared sequence. Phantom studies also demonstrated that the WSA-T2 -Prep+CHESS combination produced greater fat suppression across a range of B1 values than did a CA-T2 -Prep+CHESS combination. Lastly, in vivo measurements demonstrated that the contrast-to-noise ratio between blood and myocardium was not adversely affected by using a WSA-T2 -Prep, despite the improved abdominal and epicardial fat suppression. Additionally, vessel sharpness improved. CONCLUSION: The proposed WSA-T2 -Prep method was shown to improve fat suppression and vessel sharpness as compared to a CA-T2 -Prep technique, and to also increase fat suppression when combined with a CHESS pulse.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Intraoperative examination of sentinel axillary lymph nodes can be done by imprint cytology, frozen section, or, most recently, by PCR-based amplification of a cytokeratin signal. Using this technique, benign epithelial inclusions, representing mammary tissue displaced along the milk line, will likely generate a positive PCR signal and lead to a false-positive diagnosis of metastatic disease. To better appreciate the incidence of ectopic epithelial inclusions in axillary lymph nodes, we have performed an autopsy study, examining on 100 μm step sections 3,904 lymph nodes obtained from 160 axillary dissections in 80 patients. The median number of lymph nodes per axilla was 23 (15, 6, and 1 in levels 1, 2, and 3, respectively). A total of 30,450 hematoxylin-eosin stained slides were examined, as well as 8,825 slides immunostained with pan-cytokeratin antibodies. Despite this meticulous work-up, not a single epithelial inclusion was found in this study, suggesting that the incidence of such inclusions is much lower than the assumed 5% reported in the literature.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

BACKGROUND: Plasmid DNA vaccination is a promising approach, but studies in non-human primates and humans failed to achieve protective immunity. To optimise this technology further with focus on pulmonary administration, we developed and evaluated an adjuvant-equipped DNA carrier system based on the biopolymer chitosan. In more detail, the uptake and accompanying immune response of adjuvant Pam3Cys (Toll-like receptor-1/2 agonist) decorated chitosan DNA nanoparticles (NP) were explored by using a three-dimensional (3D) cell culture model of the human epithelial barrier. Pam3Cys functionalised and non-functionalised chitosan DNA NP were sprayed by a microsprayer onto the surface of 3D cell cultures and uptake of NP by epithelial and immune cells (blood monocyte-derived dendritic cells (MDDC) and macrophages (MDM)) was visualised by confocal laser scanning microscopy. In addition, immune activation by TLR pathway was monitored by analysis of interleukin-8 and tumor necrosis factor-α secretions (ELISA). RESULTS: At first, a high uptake rate into antigen-presenting cells (MDDC: 16-17%; MDM: 68-75%) was obtained. Although no significant difference in uptake patterns was observed for Pam3Cys adjuvant functionalised and non-functionalised DNA NP, ELISA of interleukin-8 and tumor necrosis factor-α demonstrated clearly that Pam3Cys functionalisation elicited an overall higher immune response with the ranking of Pam3Cys chitosan DNA NPâeuro0/00>âeuro0/00chitosan DNA NPâeuro0/00=âeuro0/00DNA unloaded chitosan NPâeuro0/00>âeuro0/00control (culture medium). CONCLUSIONS: Chitosan-based DNA delivery enables uptake into abluminal MDDC, which are the most immune competent cells in the human lung for the induction of antigen-specific immunity. In addition, Pam3Cys adjuvant functionalisation of chitosan DNA NP enhances significantly an environment favoring recruitment of immune cells together with a Th1 associated (cellular) immune response due to elevated IL-8 and TNF-α levels. The latter renders this DNA delivery approach attractive for potential DNA vaccination against intracellular pathogens in the lung (e.g., Mycobacterium tuberculosis or influenza virus).