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Intraoral low-temperature degradation of monolithic zirconia dental prostheses: 5-year results of a prospective clinical study with ex vivo monitoring. Dent Mater 2024; 40:198-209. [PMID: 37951752 DOI: 10.1016/j.dental.2023.11.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 11/04/2023] [Accepted: 11/04/2023] [Indexed: 11/14/2023]
Abstract
OBJECTIVES To investigate the 5-year intraoral evolution and kinetics of low-temperature degradation (LTD) of second-generation monolithic prostheses made of 3% molar yttrium-doped tetragonal zirconia polycrystal (3Y-TZP) and the influence of masticatory mechanical stresses and glaze layer on this evolution. METHODS A total of 101 posterior tooth elements were included in this prospective clinical study, which comprised ex vivo LTD monitoring (at baseline, 6 months, 1 year, 2 years, 3 years, and 5 years) using Raman spectroscopy (n = 2640 monoclinic phase measurement points per evaluation time) and scanning electron microscopy (SEM). Four types of areas (1-2 mm2 surface, six on molars, and four on premolars) were analysed on each element surface: occlusal, axial, glazed, or unglazed. Raman mapping, high-resolution SEM, and focused ion beam-SEM were performed on selected samples. RESULTS The dental prostheses developed a tetragonal-to-monoclinic transformation at the extreme surface of the material after six months in a buccal environment, and this process increased significantly over time. Over the five years of monitoring, the transformation developed nonuniformly with the presence of localised clusters of monoclinic grains. Tribological stresses generate grain pull-out from these clusters, which may raise questions regarding the release of 3Y-TZP nanoparticles into the body. The prosthesis fracture rate was 4.5% after 5 years. SIGNIFICANCE LTD developed in vivo on the surfaces of 3Y-TZP dental prostheses and progressed slowly but significantly over time, up to 5 years investigation. However, the effects of aging on the failure rate recorded and of zirconia nanoparticles released into the body require further investigation.
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Low-flow intussusception and metastable VEGFR2 signaling launch angiogenesis in ischemic muscle. SCIENCE ADVANCES 2021; 7:eabg9509. [PMID: 34826235 PMCID: PMC8626079 DOI: 10.1126/sciadv.abg9509] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Efforts to promote sprouting angiogenesis in skeletal muscles of individuals with peripheral artery disease have not been clinically successful. We discovered that, contrary to the prevailing view, angiogenesis following ischemic muscle injury in mice was not driven by endothelial sprouting. Instead, real-time imaging revealed the emergence of wide-caliber, primordial conduits with ultralow flow that rapidly transformed into a hierarchical neocirculation by transluminal bridging and intussusception. This process was accelerated by inhibiting vascular endothelial growth factor receptor-2 (VEGFR2). We probed this response by developing the first live-cell model of transluminal endothelial bridging using microfluidics. Endothelial cells subjected to ultralow shear stress could reposition inside the flowing lumen as pillars. Moreover, the low-flow lumen proved to be a privileged location for endothelial cells with reduced VEGFR2 signaling capacity, as VEGFR2 mechanosignals were boosted. These findings redefine regenerative angiogenesis in muscle as an intussusceptive process and uncover a basis for its launch.
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Early Failure of a Polyvinyl Alcohol Hydrogel Implant With Osteolysis and Foreign Body Reactions in an Ovine Model of Cartilage Repair. Am J Sports Med 2021; 49:3395-3403. [PMID: 34424105 DOI: 10.1177/03635465211033601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND Hemiarthroplasty using a polyvinyl alcohol (PVA) hydrogel synthetic implant has been suggested as a good alternative to arthrodesis for the treatment of hallux rigidus. However, failure rates as high as 20% have been recorded. PURPOSE To characterize the pathological processes in bone, cartilage, and the synovial membrane after PVA hemiarthroplasty in an ovine model with 6 months of follow-up. STUDY DESIGN Controlled laboratory study. METHODS A unilateral osteochondral defect (8-mm diameter × 10-mm depth) was made in the medial femoral condyle in 6 sheep. Animals were randomized to receive a PVA implant (n = 4) or to have an empty defect (n = 2) and were monitored for 6 months. Patellofemoral radiographs were obtained at monthly intervals, and quantitative computed tomography was performed at the end of the study. After death, the joints were macroscopically evaluated and scored. Osteochondral and synovial membrane histological findings were assessed using modified Osteoarthritis Research Society International (OARSI) and aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL) scoring systems. Immunohistochemistry using Iba1 was performed to evaluate activated macrophage infiltration. RESULTS Overall, 2 sheep with PVA implants were euthanized at 1 and 5 months because of uncontrollable pain and lameness (failed implants). Quantitative computed tomography showed that sheep with failed implants had 2.1-fold more osteolysis than those with successful implants. The sheep with failed implants had osteoarthritis with extensive glycosaminoglycan loss and cartilage fibrillation of the condyle and opposing tibial surface on histological examination. A foreign body reaction with severe chronic lymphoplasmacytic and granulomatous inflammation with giant cells was detected surrounding the implant. The synovial membrane ALVAL score was 9 of 19 and 14 of 19 in failed implants with synovial hyperplasia and lymphoplasmacytic and macrophage infiltration. In contrast, the synovial membrane in successful implants and empty defects was normal (ALVAL score = 0/19). Immunolabeling for Iba1 in failed implants confirmed extensive and dense macrophage infiltration within the condyle and synovial membrane, with the highest immunoreactive score (9/9). CONCLUSION PVA hydrogel implants had a 50% failure rate with uncontrollable pain, severe osteolysis, inflammation, and foreign body reactions. CLINICAL RELEVANCE The failure rate and pathological characteristics of the PVA implants suggest that their use should not be continued in human patients without further in vivo safety studies.
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Intraoral low-temperature degradation of monolithic zirconia dental prostheses: Results of a prospective clinical study with ex vivo monitoring. Dent Mater 2021; 37:1134-1149. [PMID: 33858665 DOI: 10.1016/j.dental.2021.03.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 02/25/2021] [Accepted: 03/29/2021] [Indexed: 02/04/2023]
Abstract
OBJECTIVE To investigate the intraoral development and kinetics of low-temperature degradation (LTD) in second-generation 3 mol.% yttria-doped tetragonal zirconia polycrystal (3Y-TZP) monolithic prostheses, as well as the influence of masticatory mechanical stress and glaze layer on it. METHODS A total of 101 posterior tooth elements were included in a prospective clinical study, which included ex vivo LTD monitoring (at baseline, 6 months, 1 year, and 2 years) using Raman spectroscopy (n = 2640 monoclinic phase measurement points per evaluation time) and SEM. Four types of areas (1-2 mm2 surface, 6 on molars, and 4 on premolars) were analyzed on each element surface: occlusal, axial, glazed, or unglazed. Raman depth mapping and high-resolution SEM were performed on the selected samples. RESULTS LTD developed in 3Y-TZP monolithic restorations 6 months after intraoral placement and progressed with time. After two years, the tetragonal-to-monoclinic transformation was non-uniform, with the presence of localized clusters of transformed grains. In axial areas, the grain aspect was typical of the classical nucleation-growth process reported for LTD, which progresses from the surface to a depth of several tens of microns. However, in occlusal areas, tribological stress generated surface crushing and grain pull-out from the clusters, which induced an underestimation of the aging process when the evaluation was limited to monoclinic phase quantification. Glazing cannot be considered a protection against LTD. SIGNIFICANCE If LTD occurs in dental prostheses in the same way as in orthopedic prostheses, its clinical impact is unknown and needs to be further studied.
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Intrinsic properties of osteomalacia bone evaluated by nanoindentation and FTIRM analysis. J Biomech 2021; 117:110247. [PMID: 33493712 DOI: 10.1016/j.jbiomech.2021.110247] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 12/29/2020] [Accepted: 01/03/2021] [Indexed: 11/17/2022]
Abstract
Osteomalacia is a pathological bone condition consisting in a deficient primary mineralization of the matrix, leading to an accumulation of osteoid tissue and reduced bone mechanical strength. The amounts, properties and organization of bone constituents at tissue level, are known to influence its mechanical properties. It is then important to investigate the relationship between mechanical behavior and tissue composition at this scale in order to provide a better understanding of bone fragility mechanisms associates with this pathology. Our purpose was to analyze the links between ultra-structural properties and the mechanical behavior of this pathological bone tissue (osteomalacia) at tissue level (mineral and osteoid separately, or global). Four bone biopsies were taken from patients with osteomalacia, and subsequently embedded, sectioned, and polished. Then nanoindentation tests were performed to determine local elastic modulus E, contact hardness Hc and true hardness H for both mineralized and organic bone phases and for the global bone. The creep of the bone was also studied using a special indentation procedure in order to assess visco-elasto-plastic (creep) bone behavior. This allowed a detailed study of the rheological models adapted to the bone and to calculate the parameters associated to a Burgers model. Ultra-structural parameters were measured by Fourier Transform InfraRed Microspectroscopy (FTIRM) on the same position as the indents. The use of rheological models confirmed a significant contribution from the organic phase on the viscous character of bone tissue. The elastic E and the elasto-plastic Hc deformation were correlated to both collagen maturity and Mineral/Matrix. The pure plastic deformation H was only correlated to the mineral phase. Our data show that mineral phase greatly affects mechanical variables (moduli and viscosities) and that organic phase (as illustrated in osteoid tissue) may play an important role in the creep behavior of bone. In conclusion, this study brings mechanical and physicochemical values for osteoid and mineral phases.
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Systematic Interrogation of Angiogenesis in the Ischemic Mouse Hind Limb: Vulnerabilities and Quality Assurance. Arterioscler Thromb Vasc Biol 2020; 40:2454-2467. [PMID: 32787524 PMCID: PMC7505144 DOI: 10.1161/atvbaha.120.315028] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Supplemental Digital Content is available in the text. Objective: There has been little success in translating preclinical studies of mouse hind limb ischemia into benefit for patients with peripheral artery disease. Using systematic strategies, we sought to define the injury and angiogenesis landscapes in mice subjected to hind limb ischemia and ascertain whether published studies to date have used an analysis strategy concordant with these data. Approach and Results: Maps of ischemic injury were generated from 22 different hind limb muscles and 33 muscle territories in 12-week-old C57BL/6 mice, based on loss or centralization of myofiber nuclei. Angiogenesis was similarly mapped based on CD (cluster of differentiation) 31–positive capillary content. Only 10 of 33 muscle territories displayed consistent muscle injury, with the distal anterior hind limb muscles most reliably injured. Angiogenesis was patchy and exclusively associated with zones of regenerated muscle (central nuclei). Angiogenesis was not observed in normal appearing muscle, necrotic muscle, or injury border zones. Systematic review of mouse hind limb angiogenesis studies identified 5147 unique publications, of which 509 met eligibility criteria for analysis. Only 7% of these analyzed manuscripts evaluated angiogenesis in distal anterior hind limb muscles and only 15% consistently examined for angiogenesis in zones of muscle regeneration. Conclusions: In 12-week C57BL/6 mice, angiogenesis postfemoral artery excision proceeds exclusively in zones of muscle regeneration. Only a minority of studies to date have analyzed angiogenesis in regions of demonstrably regenerating muscle or in high-likelihood territories. Quality assurance standards, informed by the atlas and mapping data herein, could augment data reliability and potentially help translate mouse hind limb ischemia studies to patient care.
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Obstruction of Small Arterioles in Patients with Critical Limb Ischemia due to Partial Endothelial-to-Mesenchymal Transition. iScience 2020; 23:101251. [PMID: 32629616 PMCID: PMC7322363 DOI: 10.1016/j.isci.2020.101251] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 05/03/2020] [Accepted: 06/04/2020] [Indexed: 12/12/2022] Open
Abstract
Critical limb ischemia (CLI) is a hazardous manifestation of atherosclerosis and treatment failure is common. Abnormalities in the arterioles might underlie this failure but the cellular pathobiology of microvessels in CLI is poorly understood. We analyzed 349 intramuscular arterioles in lower limb specimens from individuals with and without CLI. Arteriolar densities were 1.8-fold higher in CLI muscles. However, 33% of small (<20 μm) arterioles were stenotic and 9% were completely occluded. The lumens were closed by bulky, re-oriented endothelial cells expressing abundant N-cadherin that uniquely localized between adjacent and opposing endothelial cells. S100A4 and SNAIL1 were also expressed, supporting an endothelial-to-mesenchymal transition. SMAD2/3 was activated in occlusive endothelial cells and TGFβ1 was increased in the adjacent mural cells. These findings identify a microvascular closure process based on mesenchymal transitions in a hyper-TGFß environment that may, in part, explain the limited success of peripheral artery revascularization procedures. Small arterioles in patients with critical limb ischemia can be narrowed or closed Arteriolar occlusion is due to bulky endothelial cells Bulky endothelial cells have partially transitioned to mesenchymal cells Occlusive cells interlock laterally and apically via N-cadherin neo-adhesions
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Survival and breeding interval of an endangered marine vertebrate, the leatherback turtle Dermochelys coriacea, in French Guiana. ENDANGER SPECIES RES 2020. [DOI: 10.3354/esr01013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
In the context of global change, endangered species such as sea turtles undergo strong population dynamics changes. Understanding demographic processes inducing such changes is critical for developing appropriate measures for conservation and management. Nesting females of the French Guiana population of leatherback sea turtles Dermochelys coriacea represented 40% of the world’s total in 2001; today, they represent only 10%. Here, we analyze data from the long-term monitoring program of leatherbacks in French Guiana, based on 28 yr of capture-mark-recapture data from 46051 individuals in northwestern French Guiana. We used multievent models (multistate capture-recapture models with state uncertainty) to represent the main peculiarity of the life cycle, intermittent reproduction, and to take advantage of the use of several different types of marks to account for mark loss and incomplete detection. The average annual adult survival probability (mean ± SE) 0.789 ± 0.009 is low compared to published estimates for this species. By combining the estimates of departure and return probabilities, we provide an estimate of the interval among laying seasons equal to 2.777 ± 0.118 yr, which matches previous findings. Taking survival into account, this interval translates into an average of 1.704 ± 0.034 further reproductive seasons for an adult female having just bred, which is remarkably low compared to other long-lived vertebrates. The representation of the life cycle and mark loss in our models provides a sound structure for broader and richer analyses to extract biological information from marked individuals and offers an invaluable source of demographic information on leatherbacks, a species for which only a small segment of the population is accessible to intermittent sampling.
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Épidémiologie du cancer de la prostate résistant à la castration et métastatique : données françaises à partir du SNDS. Prog Urol 2019. [DOI: 10.1016/j.purol.2019.08.139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Validation d’un algorithme complexe dans le Système national des données de santé. Exemple avec le cancer de la prostate résistant à la castration et métastatique. Rev Epidemiol Sante Publique 2019. [DOI: 10.1016/j.respe.2019.04.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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Seno-destructive smooth muscle cells in the ascending aorta of patients with bicuspid aortic valve disease. EBioMedicine 2019; 43:54-66. [PMID: 31078518 PMCID: PMC6562112 DOI: 10.1016/j.ebiom.2019.04.060] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 04/22/2019] [Accepted: 04/30/2019] [Indexed: 12/18/2022] Open
Abstract
Background Ascending aortic aneurysms constitute an important hazard for individuals with a bicuspid aortic valve (BAV). However, the processes that degrade the aortic wall in BAV disease remain poorly understood. Methods We undertook in situ analysis of ascending aortas from 68 patients, seeking potentially damaging cellular senescence cascades. Aortas were assessed for senescence-associated-ß-galactosidase activity, p16Ink4a and p21 expression, and double-strand DNA breaks. The senescence-associated secretory phenotype (SASP) of cultured-aged BAV aortic smooth muscle cells (SMCs) was evaluated by transcript profiling and consequences probed by combined immunofluorescence and circular polarization microscopy. The contribution of p38 MAPK signaling was assessed by immunostaining and blocking strategies. Findings We uncovered SMCs at varying depths of cellular senescence within BAV- and tricuspid aortic valve (TAV)-associated aortic aneurysms. Senescent SMCs were also abundant in non-aneurysmal BAV aortas but not in non-aneurysmal TAV aortas. Multivariable analysis revealed that BAV disease independently associated with SMC senescence. Furthermre, SMC senescence was heightened at the convexity of aortas associated with right-left coronary cusp fusion. Aged BAV SMCs had a pronounced collagenolytic SASP. Moreover, senescent SMCs in the aortic wall were enriched with surface-localized MMP1 and surrounded by weakly birefringent collagen fibrils. The senescent-collagenolytic SMC phenotype depended on p38 MAPK signaling, which was chronically activated in BAV aortas. Interpretation We have identified a cellular senescence-collagen destruction axis in at-risk ascending aortas. This novel “seno-destructive” SMC phenotype could open new opportunities for managing BAV aortopathy. Fund Canadian Institutes of Health Research, Lawson Health Research Institute, Heart and Stroke Foundation of Ontario/Barnett-Ivey Chair.
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New “ductile” zirconia-based ceramics for the development of dental implants. Comput Methods Biomech Biomed Engin 2019. [DOI: 10.1080/10255842.2020.1713482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Search for γ-Ray Line Signals from Dark Matter Annihilations in the Inner Galactic Halo from 10 Years of Observations with H.E.S.S. PHYSICAL REVIEW LETTERS 2018; 120:201101. [PMID: 29864326 DOI: 10.1103/physrevlett.120.201101] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 03/05/2018] [Indexed: 06/08/2023]
Abstract
Spectral lines are among the most powerful signatures for dark matter (DM) annihilation searches in very-high-energy γ rays. The central region of the Milky Way halo is one of the most promising targets given its large amount of DM and proximity to Earth. We report on a search for a monoenergetic spectral line from self-annihilations of DM particles in the energy range from 300 GeV to 70 TeV using a two-dimensional maximum likelihood method taking advantage of both the spectral and spatial features of the signal versus background. The analysis makes use of Galactic center observations accumulated over ten years (2004-2014) with the H.E.S.S. array of ground-based Cherenkov telescopes. No significant γ-ray excess above the background is found. We derive upper limits on the annihilation cross section ⟨σv⟩ for monoenergetic DM lines at the level of 4×10^{-28} cm^{3} s^{-1} at 1 TeV, assuming an Einasto DM profile for the Milky Way halo. For a DM mass of 1 TeV, they improve over the previous ones by a factor of 6. The present constraints are the strongest obtained so far for DM particles in the mass range 300 GeV-70 TeV. Ground-based γ-ray observations have reached sufficient sensitivity to explore relevant velocity-averaged cross sections for DM annihilation into two γ-ray photons at the level expected from the thermal relic density for TeV DM particles.
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Aging resistance, mechanical properties and translucency of different yttria-stabilized zirconia ceramics for monolithic dental crown applications. Dent Mater 2018; 34:879-890. [PMID: 29598882 DOI: 10.1016/j.dental.2018.03.006] [Citation(s) in RCA: 132] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Revised: 02/24/2018] [Accepted: 03/12/2018] [Indexed: 12/21/2022]
Abstract
OBJECTIVES The dental market moves towards high-translucency monolithic zirconia dental crowns, which are usually placed either with - or without - a thin glaze layer. The microstructural features and the mechanical performances of these materials are still controversial, as well as their susceptibility to aging. This paper aims at studying these aspects in the current generation of zirconia dental crowns showing different degrees of translucency. METHODS Four different commercial zirconia materials were investigated, including one standard 'full-strength' 3Y-TZP and three grades with improved translucency. The microstructural features (phase composition and assemblage, grain size) were carefully studied, as well as mechanical properties (biaxial bending strength and indentation toughness), translucency and aging behavior (in autoclave at 134°C). Aging was conducted on crowns with and without glaze to better represent clinical uses. RESULTS Important differences are found in terms of microstructures among the materials in terms of cubic phase content and yttria in the tetragonal phase, leading to different optical, mechanical and aging resistance properties. We show that higher cubic phase content leads to better translucency and stability in water steam, but at the expense of strength and toughness. A compromise is always inevitable between translucency and aging resistance on one side and mechanical properties on the other side. SIGNIFICANCE
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Sub-surface assessment of hydrothermal ageing in zirconia-containing femoral heads for hip joint applications. Acta Biomater 2018; 68:286-295. [PMID: 29274479 DOI: 10.1016/j.actbio.2017.12.021] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 12/14/2017] [Accepted: 12/17/2017] [Indexed: 02/04/2023]
Abstract
Zirconia-based materials have been used in orthopaedics since the 1980s, with large success, mainly thanks to transformation toughening. On the other hand, their main drawback is their potential sensitivity to hydrothermal ageing, i.e. tetragonal to monoclinic phase transformation on their surface in the presence of water. Hydrothermal ageing may result in roughness increase and microcracking of the surface. In this article the hydrothermal ageing behaviour of three medical-grade zirconia-based materials is assessed at high temperature and extrapolated to room or body temperature. The degradation is also characterized by FIB/SEM nano-tomography to better assess sub-surface evolutions. In both zirconia and alumina-toughened zirconia (ATZ), ageing results in the presence of a homogenous transformed layer of constant thickness whose growth rate is about 8 times slower in ATZ than in zirconia. Microcracking occurs in the entire transformed layer in zirconia, but was much less relevant in ATZ. Zirconia-toughened alumina (ZTA) is much less prone to ageing. In ZTA ageing results in a thin transformed layer in which the monoclinic fraction decreases with depth. No microcracking was observed in ZTA. STATEMENT OF SIGNIFICANCE This article details the microstructural evolution of the surface of three zirconia-based ceramics when exposed to water (hydrothermal ageing), and establishes a time-temperature equivalences of these evolutions. It shows that different zirconia-alumina composites do not degrade the same way: zirconia and alumina-toughened zirconia present a homogeneous degraded zone of constant thickness, whereas zirconia-toughened-alumina presents a gradient of transformation. These new findings will help understanding better the hydrothermal degradation of zirconia based materials, and in particular will facilitate a better prediction of the durability of zirconia-based devices such as orthopaedic implants and dental devices (implants, crowns, abutments…).
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STW 5 prevents stress-induced changes in intestinal permeability in mice in-vivo. Am J Transl Res 2017. [DOI: 10.1055/s-0037-1608490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Intestinal permeability induced by psychological stress: Action of STW 5. Am J Transl Res 2017. [DOI: 10.1055/s-0037-1608493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Effet protecteur de l’administration de membranes du globule gras du lait et L. fermentum CECT 5716 sur les fonctions digestives et sur la réponse inflammatoire dans un modèle de rat nouveau-né. NUTR CLIN METAB 2017. [DOI: 10.1016/j.nupar.2017.06.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Abstract
Ceramic materials are prone to slow crack growth, resulting in strength degradation over time. Although yttria-stabilized zirconia (Y-TZP) ceramics have higher crack resistance than other dental ceramics, their aging susceptibility threatens their long-term performance in aqueous environments such as the oral cavity. Unfortunately, increasing the aging resistance of Y-TZP ceramics normally reduces their crack resistance. Our recently conducted systematic study of doping 3Y-TZP with various trivalent cations revealed that lanthanum oxide (La2O3) and aluminum oxide (Al2O3) have the most potent effect to retard the aging kinetics of 3Y-TZP. In this study, the crack-propagation behavior of La2O3 and Al2O3 co-doped 3Y-TZP ceramics was investigated by double-torsion methods. The grain boundaries were examined using scanning transmission electron microscopy and energy-dispersive spectroscopy (STEM-EDS). Correlating these analytic data with hydrothermal aging studies using different doping systems, a strategy to strongly bind the segregated dopant cations with the oxygen vacancies at the zirconia-grain boundary was found to improve effectively the aging resistance of Y-TZP ceramics without affecting the resistance to crack propagation.
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Renforcement de la barrière épithéliale intestinale par la souche probiotique Lactobacillus fermentum CECT 5716 chez le raton nouveau-né. NUTR CLIN METAB 2017. [DOI: 10.1016/j.nupar.2016.10.044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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H.E.S.S. Limits on Linelike Dark Matter Signatures in the 100 GeV to 2 TeV Energy Range Close to the Galactic Center. PHYSICAL REVIEW LETTERS 2016; 117:151302. [PMID: 27768338 DOI: 10.1103/physrevlett.117.151302] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Indexed: 06/06/2023]
Abstract
UNLABELLED A search for dark matter linelike signals iss performed in the vicinity of the Galactic Center by the H.E.S.S. experiment on observational data taken in 2014. An unbinned likelihood analysis iss developed to improve the sensitivity to linelike signals. The upgraded analysis along with newer data extend the energy coverage of the previous measurement down to 100 GeV. The 18 h of data collected with the H.E.S.S. array allow one to rule out at 95% C.L. the presence of a 130 GeV line (at l=-1.5°, b=0° and for a dark matter profile centered at this location) previously reported in Fermi-LAT data. This new analysis overlaps significantly in energy with previous Fermi-LAT and H.E.S.S. RESULTS No significant excess associated with dark matter annihilations was found in the energy range of 100 GeV to 2 TeV and upper limits on the gamma-ray flux and the velocity weighted annihilation cross section are derived adopting an Einasto dark matter halo profile. Expected limits for present and future large statistics H.E.S.S. observations are also given.
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Search for Dark Matter Annihilations towards the Inner Galactic Halo from 10 Years of Observations with H.E.S.S. PHYSICAL REVIEW LETTERS 2016; 117:111301. [PMID: 27661677 DOI: 10.1103/physrevlett.117.111301] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Indexed: 06/06/2023]
Abstract
The inner region of the Milky Way halo harbors a large amount of dark matter (DM). Given its proximity, it is one of the most promising targets to look for DM. We report on a search for the annihilations of DM particles using γ-ray observations towards the inner 300 pc of the Milky Way, with the H.E.S.S. array of ground-based Cherenkov telescopes. The analysis is based on a 2D maximum likelihood method using Galactic Center (GC) data accumulated by H.E.S.S. over the last 10 years (2004-2014), and does not show any significant γ-ray signal above background. Assuming Einasto and Navarro-Frenk-White DM density profiles at the GC, we derive upper limits on the annihilation cross section ⟨σv⟩. These constraints are the strongest obtained so far in the TeV DM mass range and improve upon previous limits by a factor 5. For the Einasto profile, the constraints reach ⟨σv⟩ values of 6×10^{-26} cm^{3} s^{-1} in the W^{+}W^{-} channel for a DM particle mass of 1.5 TeV, and 2×10^{-26} cm^{3} s^{-1} in the τ^{+}τ^{-} channel for a 1 TeV mass. For the first time, ground-based γ-ray observations have reached sufficient sensitivity to probe ⟨σv⟩ values expected from the thermal relic density for TeV DM particles.
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Efflux Pump Blockers in Gram-Negative Bacteria: The New Generation of Hydantoin Based-Modulators to Improve Antibiotic Activity. Front Microbiol 2016; 7:622. [PMID: 27199950 PMCID: PMC4853399 DOI: 10.3389/fmicb.2016.00622] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 04/15/2016] [Indexed: 01/21/2023] Open
Abstract
Multidrug resistant (MDR) bacteria are an increasing health problem with the shortage of new active antibiotic agents. Among effective mechanisms that contribute to the spread of MDR Gram-negative bacteria are drug efflux pumps that expel clinically important antibiotic classes out of the cell. Drug pumps are attractive targets to restore the susceptibility toward the expelled antibiotics by impairing their efflux activity. Arylhydantoin derivatives were investigated for their potentiation of activities of selected antibiotics described as efflux substrates in Enterobacter aerogenes expressing or not AcrAB pump. Several compounds increased the bacterial susceptibility toward nalidixic acid, chloramphenicol and sparfloxacin and were further pharmacomodulated to obtain a better activity against the AcrAB producing bacteria.
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CAPECO: Cost evaluation of community acquired pneumonia managed in primary care. Vaccine 2016; 34:2275-80. [PMID: 26979138 DOI: 10.1016/j.vaccine.2016.03.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Revised: 02/05/2016] [Accepted: 03/04/2016] [Indexed: 10/22/2022]
Abstract
BACKGROUND Estimating the economic burden of community acquired pneumonia (CAP) managed in ambulatory setting is needed in France since no data are available. METHOD A retrospective study (CAPECO) was conducted based on a prospective French study describing patients with suspected CAP managed in primary care (CAPA). The aim of the CAPECO study was to estimate and explain medical costs of a disease episode in CAP patients only followed in ambulatory care and in hospitalised patients. Primary endpoints were the direct medical costs, impact on productivity and costs of incident CAP over one year. Secondary endpoint was to describe predictive factors of costs, hospital admission and stay length. RESULTS In this cohort of 886 patients, resulting in an incidence of CAP of 400 per 100,000 inhabitants per year, the mean direct medical cost of a disease episode of CAP was € 118.8 for strictly ambulatory patients with an equal weight for medical time, drugs, diagnostic procedures and tests. This direct cost was € 102.1 before admission for patients who were finally hospitalised. The mean cost of hospital admissions was € 3522.9. Main predictive factors of hospital admission and stay length were respectively a history of chronic respiratory disease and older age. Factors of direct medical cost were prescribing X-ray examination and having a positive X-ray. The impact of a disease episode on productivity was € 1980 (sd 1400) per ambulatory episode and € 5425 (sd 4760) per episode leading to hospital admission. CONCLUSION Costs per ambulatory episode were modest but increased substantially in hospitalised patients, who were more numerous when chronic respiratory disorders were present and in the elderly. Indirect costs were significant. Deciders should thus consider both direct and indirect costs when assessing preventive interventions in the context of this disease.
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In vitro aging and mechanical properties of translucent monolithic zirconia. Dent Mater 2016. [DOI: 10.1016/j.dental.2016.08.205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Hydrothermal degradation of monolithic zirconia: Guidelines for finishing treatments. Dent Mater 2016. [DOI: 10.1016/j.dental.2016.08.136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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[Epileptic seizures and hematemesis in a young patient with sickle cell disease]. Rev Med Interne 2015; 37:367-70. [PMID: 26387760 DOI: 10.1016/j.revmed.2015.08.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 08/07/2015] [Accepted: 08/13/2015] [Indexed: 11/15/2022]
Abstract
INTRODUCTION Sickle cell disease is a multi-faceted disease, which can affect all organs. Here, we report the case of a young woman whose clinical presentation was confusing. CASE REPORT An 18-year-old patient from Martinique in Caribbean area presented to the emergency room with widespread pain, as part of a vaso-occlusive crisis. She reported being followed for SS sickle cell anemia, with a history of vaso-occlusive crises and exchange transfusions in the past. Her hemoglobin rate was 83g/L. She was treated with opioid analgesics. Then, she presented several generalized tonic-clonic seizures and major episodes of hematemesis, which proved to be simulated by the patient, whose hemoglobin electrophoresis result was finally AS. CONCLUSION This patient had therefore the Münchausen syndrome, mimicking sickle cell anemia, like eight other cases reported in the literature.
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Effect of different surface treatments on the hydrothermal degradation of a 3Y-TZP ceramic for dental implants. Dent Mater 2014; 30:1136-46. [DOI: 10.1016/j.dental.2014.07.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 05/20/2014] [Accepted: 07/09/2014] [Indexed: 02/04/2023]
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SFRP CO-08 – Conséquence d’une antibiothérapie néonatale sur la barrière intestinale du raton. Arch Pediatr 2014. [DOI: 10.1016/s0929-693x(14)72246-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Novel extrudates based on the multiscale packing of alumina particles and boehmite or aluminophosphate binders. POWDER TECHNOL 2014. [DOI: 10.1016/j.powtec.2013.09.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Natural extracts stimulate membrane-associated mechanisms of resistance in Gram-negative bacteria. Lett Appl Microbiol 2014; 58:472-7. [PMID: 24447247 DOI: 10.1111/lam.12216] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Revised: 12/23/2013] [Accepted: 01/07/2014] [Indexed: 12/29/2022]
Abstract
UNLABELLED Several mechanisms are involved in the bacterial resistance towards antimicrobial agents. The membrane-associated mechanisms of resistance were studied in Escherichia coli strains after incubation with Thymus maroccanus essential oil, its major components (carvacrol and thymol) or with certain antibiotics. The minimum inhibitory concentration (MIC) and the expression of membrane proteins, porins and efflux pumps were determined in wild type and derivative strains. Derivative strains adapted to different compounds displayed a high level of resistance to all tested antibiotics. The MIC increase is associated with an overexpression of an efflux pump immunorelated to AcrAB-TolC in various variants. Interestingly, the expression of outer membrane proteins slightly decreases in these strains. We demonstrate that the increase in antibiotic resistance correlates with membrane changes observed in the variants. This type of bacterial adaptation to natural compounds can occur in vivo providing the emergence/selection of bacteria less susceptible to clinically used antibiotics. SIGNIFICANCE AND IMPACT OF THE STUDY Thymus maroccanus essential oil and some major components are able to select variants that modify the expression of transporters involved in the influx (porins) and in the efflux (AcrAB family) of various drugs. Importantly, these membrane proteins are involved in the transport of natural compounds and several antibiotic families. This special 'membrane adaptation' can explain the persistence of less susceptible/tolerant bacteria in the environment where natural compounds are present and the continuous stimulation of efflux systems in these bacteria.
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Greffe cutanée de plaies chroniques par ensemencement cellulaire autologue. Ann Dermatol Venereol 2013. [DOI: 10.1016/j.annder.2013.09.332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Combining ageing and wear to assess the durability of zirconia-based ceramic heads for total hip arthroplasty. Acta Biomater 2013; 9:7545-55. [PMID: 23541600 DOI: 10.1016/j.actbio.2013.03.030] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Revised: 02/13/2013] [Accepted: 03/20/2013] [Indexed: 02/04/2023]
Abstract
The degradation of zirconia-based ceramic components for total hip arthroplasty (head and cup) has been the topic of many works. However, the correlation between what is measured in vivo and what is expected from in vitro simulations on hip simulators may be sometimes feeble, especially where zirconia component are concerned, mainly due to a lack of representativeness of in vitro experiments. The present study seeks to explore the combined effects of hydrothermal ageing and wear on zirconia components. It shows that hydrothermal ageing increases the roughness of zirconia components, which in turn might increase the wear rate of the polyethylene counterparts. Moreover, the friction during hip simulation increases the ageing rate of the zirconia components. This auto-accelerating degradation may explain some of the poor long-term in vivo results of zirconia hip prostheses reported in the literature. Finally, it is shown that zirconia-toughened alumina components may be free from this combined degradation.
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New Peptide-based antimicrobials for tackling drug resistance in bacteria: single-cell fluorescence imaging. ACS Med Chem Lett 2013; 4:556-9. [PMID: 24900708 DOI: 10.1021/ml400073g] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 05/07/2013] [Indexed: 10/26/2022] Open
Abstract
New peptide molecules with metal binding abilities proved to be active against multidrug resistant clinical isolates. One of them labeled with a dansylated lysine has been imaged inside single-multidrug resistant bacteria cells by deep ultraviolet fluorescence, showing a heterogeneous subcellular localization. The fluorescence intensity is clearly related to the accumulation of the drug inside the bacteria, being dependent both on its concentration and on the incubation time with cells.
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Thymus maroccanusessential oil, a membranotropic compound active on Gram-negative bacteria and resistant isolates. J Appl Microbiol 2012; 113:1120-9. [DOI: 10.1111/j.1365-2672.2012.05401.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Revised: 06/08/2012] [Accepted: 07/13/2012] [Indexed: 12/18/2022]
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Antibiotic transport in resistant bacteria: synchrotron UV fluorescence microscopy to determine antibiotic accumulation with single cell resolution. PLoS One 2012; 7:e38624. [PMID: 22719907 PMCID: PMC3373604 DOI: 10.1371/journal.pone.0038624] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Accepted: 05/13/2012] [Indexed: 12/11/2022] Open
Abstract
A molecular definition of the mechanism conferring bacterial multidrug resistance is clinically crucial and today methods for quantitative determination of the uptake of antimicrobial agents with single cell resolution are missing. Using the naturally occurring fluorescence of antibacterial agents after deep ultraviolet (DUV) excitation, we developed a method to non-invasively monitor the quinolones uptake in single bacteria. Our approach is based on a DUV fluorescence microscope coupled to a synchrotron beamline providing tuneable excitation from 200 to 600 nm. A full spectrum was acquired at each pixel of the image, to study the DUV excited fluorescence emitted from quinolones within single bacteria. Measuring spectra allowed us to separate the antibiotic fluorescence from the autofluorescence contribution. By performing spectroscopic analysis, the quantification of the antibiotic signal was possible. To our knowledge, this is the first time that the intracellular accumulation of a clinical antibiotic could be determined and discussed in relation with the level of drug susceptibility for a multiresistant strain. This method is especially important to follow the behavior of quinolone molecules at individual cell level, to quantify the intracellular concentration of the antibiotic and develop new strategies to combat the dissemination of MDR-bacteria. In addition, this original approach also indicates the heterogeneity of bacterial population when the same strain is under environmental stress like antibiotic attack.
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Cover Picture: Hydroxamic Acids as Potent Inhibitors of Fe IIand Mn IIE. coliMethionine Aminopeptidase: Biological Activities and X-ray Structures of Oxazole Hydroxamate- EcMetAP-Mn Complexes (ChemMedChem 6/2012). ChemMedChem 2012. [DOI: 10.1002/cmdc.201290024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Hydroxamic Acids as Potent Inhibitors of FeIIand MnIIE. coliMethionine Aminopeptidase: Biological Activities and X-ray Structures of Oxazole Hydroxamate-EcMetAP-Mn Complexes. ChemMedChem 2012; 7:1020-30. [DOI: 10.1002/cmdc.201200076] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 03/07/2012] [Indexed: 01/06/2023]
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Antibacterial activity of Thymus maroccanus and Thymus broussonetii essential oils against nosocomial infection - bacteria and their synergistic potential with antibiotics. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2012; 19:464-471. [PMID: 22257599 DOI: 10.1016/j.phymed.2011.12.003] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Revised: 11/14/2011] [Accepted: 12/13/2011] [Indexed: 05/28/2023]
Abstract
The aim of this study was to evaluate the antibacterial effect of the association between conventional antibiotics and essential oils (EOs) of endemic Moroccan thyme species, Thymus maroccanus and T. broussonetii, on antibiotic-resistant bacteria involved in nosocomial infections. Synergistic interactions between antibiotics (ciprofloxacin, gentamicin, pristinamycin, and cefixime) and EOs, and between T. maroccanus and T. Broussonetii EOs were determined by the checkerboard test. Serial dilutions of two antimicrobial agents were mixed together so that each row (and column) contained a fixed amount of the first agent and increasing amounts of the second one. The results indicate that the oils had a high inhibitory activity against tested bacteria, except for Pseudomonas aeruginosa. In parallel with the increase of cellular killing, the release of 260nm-absorbing materials from bacterial cells, treated with EOs, increased in response to oil concentration. Out of 80 combinations tested between EOs and antibiotics, 71% showed total synergism, 20% had partial synergistic interaction and 9% showed no effect. Combination with carvacrol, the major constituent of T. maroccanus and T. broussonetii, showed also an interesting synergistic effect in combination with ciprofloxacin. The effect on Gram-positive bacteria was more important than on Gram-negative bacteria. These findings are very promising since the use of these combinations for nosocomial infections treatment is likely to reduce the minimum effective dose of the antibiotics, thus minimizing their possible toxic side effects and treatment cost. However, further investigations are needed to assess the potential for therapeutic application.
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New peptide deformylase inhibitors and cooperative interaction: a combination to improve antibacterial activity. J Antimicrob Chemother 2012; 67:1392-400. [PMID: 22378679 DOI: 10.1093/jac/dks058] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
OBJECTIVES Bacterial drug resistance is a worrying public health problem and there is an urgent need for research and development to provide new antibacterial molecules. Peptide deformylase (PDF) is now a well-described intracellular target selected for the design of a new antibiotic group, PDF inhibitors (PDFIs). The initial bacterial susceptibility to an inhibitor of a cytoplasmic target is directly associated with the diffusion of the compound through the membrane barrier of Gram-negative bacteria and with its cytosolic accumulation at the required concentration. METHODS We have recently demonstrated that the activity of different PDFIs is strongly dependent on the accumulation of the active molecules by using permeabilizing agents, efflux inhibitors or efflux-mutated strains. In this work we assessed various combination protocols using different putative inhibitors (PDFIs, methionine aminopeptidase inhibitors etc.) to improve antibacterial activity against various resistant Gram-negative bacteria. RESULTS The maximum effect was observed when combining actinonin with a dual inhibitor of methionine aminopeptidase and PDF, this molecule being also able to interact with the target while actinonin is bound to the PDF active site. CONCLUSIONS Such a combination of inhibitors acting on two tightly associated metabolic steps results in a cooperative effect on bacterial cells and opens an original way to combat multidrug-resistant bacteria.
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76 and 14 kDa polypeptides, two major components released from amphibian urinary bladder epithelium. Localization and potential role. Biol Cell 2012. [DOI: 10.1111/j.1768-322x.1989.tb00826.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Amine-alkyl derivatives of hydantoin: new tool to combat resistant bacteria. Eur J Med Chem 2011; 46:5807-16. [PMID: 22000919 DOI: 10.1016/j.ejmech.2011.09.032] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Revised: 09/20/2011] [Accepted: 09/20/2011] [Indexed: 02/04/2023]
Abstract
A series of new 5,5-diphenylhydantoin derivatives with various amine-alkyl terminal fragments at N1-position were synthesized. Then a series of twenty-eight compounds with the same hydantoin scaffold were evaluated for their potency to combat bacterial MultiDrug Resistance (MDR). Intrinsic antibacterial activities were first evaluated. As these compounds showed no direct activity on bacteria, their influence on minimal inhibitory concentration (MIC) of nalidixic acid was tested in two strains of Enterobacter aerogenes: the reference-strain ATCC-13048 and the CM-64 strain which over-produces AcrAB-TolC efflux pump. The compounds showed moderate- or low- anti-MDR properties. According to SAR-studies, hit compounds containing 2-methoxyphenylpiperazine at N1-terminal fragment and methylcarboxyl acid one at N3-position of hydantoin have been identified for further microbiological studies and pharmacomodulations to develop efflux pump inhibitors.
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Quantification of the pathological response and fate in the lung and pleura of chrysotile in combination with fine particles compared to amosite-asbestos following short-term inhalation exposure. Inhal Toxicol 2011; 23:372-91. [PMID: 21639706 PMCID: PMC3128827 DOI: 10.3109/08958378.2011.575413] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
The marked difference in biopersistence and pathological response between chrysotile and amphibole asbestos has been well documented. This study is unique in that it has examined a commercial chrysotile product that was used as a joint compound. The pathological response was quantified in the lung and translocation of fibers to and pathological response in the pleural cavity determined. This paper presents the final results from the study. Rats were exposed by inhalation 6 h/day for 5 days to a well-defined fiber aerosol. Subgroups were examined through 1 year. The translocation to and pathological response in the pleura was examined by scanning electron microscopy and confocal microscopy (CM) using noninvasive methods.The number and size of fibers was quantified using transmission electron microscopy and CM. This is the first study to use such techniques to characterize fiber translocation to and the response of the pleural cavity. Amosite fibers were found to remain partly or fully imbedded in the interstitial space through 1 year and quickly produced granulomas (0 days) and interstitial fibrosis (28 days). Amosite fibers were observed penetrating the visceral pleural wall and were found on the parietal pleural within 7 days postexposure with a concomitant inflammatory response seen by 14 days. Pleural fibrin deposition, fibrosis, and adhesions were observed, similar to that reported in humans in response to amphibole asbestos. No cellular or inflammatory response was observed in the lung or the pleural cavity in response to the chrysotile and sanded particles (CSP) exposure. These results provide confirmation of the important differences between CSP and amphibole asbestos.
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Essential oils from Moroccan plants as potential chemosensitisers restoring antibiotic activity in resistant Gram-negative bacteria. Int J Antimicrob Agents 2011; 38:325-30. [PMID: 21752605 DOI: 10.1016/j.ijantimicag.2011.05.005] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 04/29/2011] [Accepted: 05/03/2011] [Indexed: 11/16/2022]
Abstract
Bacterial drug resistance is a worrying public health problem. Antibiotic efflux is a major non-specific resistance mechanism used by bacteria, and efflux pumps are involved in the low-level susceptibility of various important Gram-negative pathogens. Use of molecules that can block bacterial pumps is an attractive strategy, but several studies report only partial efficacy owing to limits of these molecules (stability, selectivity, bioavailability, toxicity, etc.). The objective of this study was to search for natural sources of molecules able to inhibit efflux pump systems of resistant Gram-negative bacteria (Escherichia coli, Enterobacter aerogenes, Klebsiella pneumoniae, Salmonella enterica serotype Typhimurium and Pseudomonas aeruginosa). The results indicate that the studied essential oils exhibit interesting activity against the tested bacteria. This activity was significantly enhanced in the presence of an efflux pump inhibitor such as phenylalanine arginyl β-naphthylamide (PAβN). The role of lipopolysaccharide (LPS) structure in the effect of essential oils was also reported in Salmonella LPS deep-rough mutants. In addition, essential oils of Thymus maroccanus and Thymus broussonetii, used at a low concentration (a fraction of the minimum inhibitory concentration), are able to significantly increase chloramphenicol susceptibility of several resistant isolates. These results demonstrate that these essential oils can alter efflux pump activity and may be attractive candidates to develop new drugs for chemosensitising multidrug-resistant strains to clinically used antibiotics.
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n-3 polyunsaturated fatty acids in the maternal diet modify the postnatal development of nervous regulation of intestinal permeability in piglets. J Physiol 2011; 589:4341-52. [PMID: 21746785 DOI: 10.1113/jphysiol.2011.214056] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The intestinal epithelial barrier (IEB) plays a key role in the maintenance of gut homeostasis and the development of the immune system in newborns. The enteric nervous system (ENS), a key regulator of gastrointestinal functions, has been shown to be modulated by nutritional factors. However, it remains currently unknown whether maternal diet, in particular n-3 polyunsaturated fatty acids (n-3PUFAs), can impact upon the IEB in newborn piglets and whether the ENS is involved in this effect. Sows received either a control diet (lard based) or an n-3PUFA diet (linseed oil based) during gestation and lactation. Intestinal paracellular permeability was assessed in Ussing chambers on piglets at birth, 3, 7, 14, 21 and 28 postnatal days (PND). Basal jejunal permeability increased significantly and similarly in both groups until PND14 and decreased thereafter. However, at PND28, permeability was higher in n-3PUFA animals as compared to controls. In addition, a vasoactive intestinal peptide (VIP) receptor antagonist increased paracellular permeability in controls but not in n-3PUFA piglets. Conversely, atropine and hexamethonium decreased paracellular permeability in the n-3PUFA group but not in the control group. Moreover, the n-3PUFA diet increased the proportion of choline acetyltransferase (ChAT)-immunoreactive (IR) neurons and decreased the proportion of VIP-IR neurons in the submucosal plexus of piglet jejunum compared to controls. In addition, in primary culture of rat ENS, we showed that 20:5n-3 but not 18:3n-3 increased the proportion of ChAT-IR neurons and decreased the proportion of VIP-IR neurons. In conclusion, supplementation of the maternal diet with n-3PUFAs modified intestinal permeability probably via diet-induced neuroplastic changes in the ENS of newborn piglets.
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The pathological response and fate in the lung and pleura of chrysotile in combination with fine particles compared to amosite asbestos following short-term inhalation exposure: interim results. Inhal Toxicol 2011; 22:937-62. [PMID: 20695727 DOI: 10.3109/08958378.2010.497818] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The pathological response and translocation of a commercial chrysotile product similar to that which was used through the mid-1970s in a joint compound intended for sealing the interface between adjacent wall boards was evaluated in comparison to amosite asbestos. This study was unique in that it presents a combined real-world exposure and was the first study to investigate whether there were differences between chrysotile and amosite asbestos fibers in time course, size distribution, and pathological response in the pleural cavity. Rats were exposed by inhalation 6 h/day for 5 days to either sanded joint compound consisting of both chrysotile fibers and sanded joint compound particles (CSP) or amosite asbestos. Subgroups were examined through 1-year postexposure. No pathological response was observed at any time point in the CSP-exposure group. The long chrysotile fibers (L > 20 microm) cleared rapidly (T(1/2) of 4.5 days) and were not observed in the pleural cavity. In contrast, a rapid inflammatory response occurred in the lung following exposure to amosite resulting in Wagner grade 4 interstitial fibrosis within 28 days. Long amosite fibers had a T(1/2) > 1000 days and were observed in the pleural cavity within 7 days postexposure. By 90 days the long amosite fibers were associated with a marked inflammatory response on the parietal pleural. This study provides support that CSP following inhalation would not initiate an inflammatory response in the lung, and that the chrysotile fibers present do not migrate to, or cause an inflammatory response in the pleural cavity, the site of mesothelioma formation.
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Strategies for bypassing the membrane barrier in multidrug resistant Gram-negative bacteria. FEBS Lett 2011; 585:1682-90. [DOI: 10.1016/j.febslet.2011.04.054] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Revised: 04/20/2011] [Accepted: 04/21/2011] [Indexed: 10/18/2022]
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Étude des disparités géographiques et sectorielles dans le recours aux molécules onéreuses en oncologie. Rev Epidemiol Sante Publique 2011. [DOI: 10.1016/j.respe.2011.02.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022] Open
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