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J L Lefaix - One of the best experts on this subject based on the ideXlab platform.

  • the radiation induced fibroatrophic process therapeutic perspective via the antioxidant pathway
    Radiotherapy and Oncology, 2004
    Co-Authors: S Delanian, J L Lefaix
    Abstract:

    The radiation-induced fibroatrophic process (RIF) constitutes a late, local and unavoidable sequela to high-dose radiotherapy, traditionally considered irreversible. Today, this process is partly reversible, thanks to recent progress in understanding the physiopathology of the lesions it causes and the results of recent clinical trials using antioxidant therapy. This review includes a synthetic description of the static and dynamic features of the RIF process, as reflected by its clinical, instrumental and histopathological characteristics, and by its cellular and molecular regulation. Schematically, three successive clinical and histopathological phases can be distinguished: a pre-fibrotic aspecific inflammatory phase, a constitutive fibrotic cellular phase, and a Matrix Densification and remodelling phase, possibly ending in terminal tissular necrosis. The respective roles of the chief actors in the RIF process are defined, as well as their development with time. A fibroblastic stromal hypothesis is suggested revolving around a 'gravitational effect' exerted by the couple ROS (reactive oxygen species)--fibroblasts, and partly mediated by TGF-beta1. A variety of strategies have been tested for the management of RIF. In the light of the mechanisms described, a curative procedure has been proposed via the antioxidant pathway. In particular, it was showed that superoxide dismutase and combined pentoxifylline-tocopherol treatment enables the process of established radiation-induced fibroatrophy to be greatly reduced or even reversed, both in clinical practice and animal experiments. The efficacy of combined pentoxifylline-tocopherol treatment in superficial RIF was confirmed in a randomised clinical trial, and then in successful phase II trials especially in uterine fibroatrophy and osteoradionecrosis. It is of critical importance to evaluate these new management approaches in larger clinical trials and to improve the recording of results for better outcome analysis. Mechanistic studies are always necessary to improve understanding of the RIF process and the antifibrotic drug action.

  • the radiation induced fibroatrophic process therapeutic perspective via the antioxidant pathway
    Radiotherapy and Oncology, 2004
    Co-Authors: S Delanian, J L Lefaix
    Abstract:

    Abstract The radiation-induced fibroatrophic process (RIF) constitutes a late, local and unavoidable sequela to high-dose radiotherapy, traditionally considered irreversible. Today, this process is partly reversible, thanks to recent progress in understanding the physiopathology of the lesions it causes and the results of recent clinical trials using antioxidant therapy. This review includes a synthetic description of the static and dynamic features of the RIF process, as reflected by its clinical, instrumental and histopathological characteristics, and by its cellular and molecular regulation. Schematically, three successive clinical and histopathological phases can be distinguished: a pre-fibrotic aspecific inflammatory phase, a constitutive fibrotic cellular phase, and a Matrix Densification and remodelling phase, possibly ending in terminal tissular necrosis. The respective roles of the chief actors in the RIF process are defined, as well as their development with time. A fibroblastic stromal hypothesis is suggested revolving around a ‘gravitational effect’ exerted by the couple ROS (reactive oxygen species)—fibroblasts, and partly mediated by TGF-β1. A variety of strategies have been tested for the management of RIF. In the light of the mechanisms described, a curative procedure has been proposed via the antioxidant pathway. In particular, it was showed that superoxide dismutase and combined pentoxifylline–tocopherol treatment enables the process of established radiation-induced fibroatrophy to be greatly reduced or even reversed, both in clinical practice and animal experiments. The efficacy of combined pentoxifylline–tocopherol treatment in superficial RIF was confirmed in a randomised clinical trial, and then in successful phase II trials especially in uterine fibroatrophy and osteoradionecrosis. It is of critical importance to evaluate these new management approaches in larger clinical trials and to improve the recording of results for better outcome analysis. Mechanistic studies are always necessary to improve understanding of the RIF process and the antifibrotic drug action.

S Delanian - One of the best experts on this subject based on the ideXlab platform.

  • the radiation induced fibroatrophic process therapeutic perspective via the antioxidant pathway
    Radiotherapy and Oncology, 2004
    Co-Authors: S Delanian, J L Lefaix
    Abstract:

    The radiation-induced fibroatrophic process (RIF) constitutes a late, local and unavoidable sequela to high-dose radiotherapy, traditionally considered irreversible. Today, this process is partly reversible, thanks to recent progress in understanding the physiopathology of the lesions it causes and the results of recent clinical trials using antioxidant therapy. This review includes a synthetic description of the static and dynamic features of the RIF process, as reflected by its clinical, instrumental and histopathological characteristics, and by its cellular and molecular regulation. Schematically, three successive clinical and histopathological phases can be distinguished: a pre-fibrotic aspecific inflammatory phase, a constitutive fibrotic cellular phase, and a Matrix Densification and remodelling phase, possibly ending in terminal tissular necrosis. The respective roles of the chief actors in the RIF process are defined, as well as their development with time. A fibroblastic stromal hypothesis is suggested revolving around a 'gravitational effect' exerted by the couple ROS (reactive oxygen species)--fibroblasts, and partly mediated by TGF-beta1. A variety of strategies have been tested for the management of RIF. In the light of the mechanisms described, a curative procedure has been proposed via the antioxidant pathway. In particular, it was showed that superoxide dismutase and combined pentoxifylline-tocopherol treatment enables the process of established radiation-induced fibroatrophy to be greatly reduced or even reversed, both in clinical practice and animal experiments. The efficacy of combined pentoxifylline-tocopherol treatment in superficial RIF was confirmed in a randomised clinical trial, and then in successful phase II trials especially in uterine fibroatrophy and osteoradionecrosis. It is of critical importance to evaluate these new management approaches in larger clinical trials and to improve the recording of results for better outcome analysis. Mechanistic studies are always necessary to improve understanding of the RIF process and the antifibrotic drug action.

  • the radiation induced fibroatrophic process therapeutic perspective via the antioxidant pathway
    Radiotherapy and Oncology, 2004
    Co-Authors: S Delanian, J L Lefaix
    Abstract:

    Abstract The radiation-induced fibroatrophic process (RIF) constitutes a late, local and unavoidable sequela to high-dose radiotherapy, traditionally considered irreversible. Today, this process is partly reversible, thanks to recent progress in understanding the physiopathology of the lesions it causes and the results of recent clinical trials using antioxidant therapy. This review includes a synthetic description of the static and dynamic features of the RIF process, as reflected by its clinical, instrumental and histopathological characteristics, and by its cellular and molecular regulation. Schematically, three successive clinical and histopathological phases can be distinguished: a pre-fibrotic aspecific inflammatory phase, a constitutive fibrotic cellular phase, and a Matrix Densification and remodelling phase, possibly ending in terminal tissular necrosis. The respective roles of the chief actors in the RIF process are defined, as well as their development with time. A fibroblastic stromal hypothesis is suggested revolving around a ‘gravitational effect’ exerted by the couple ROS (reactive oxygen species)—fibroblasts, and partly mediated by TGF-β1. A variety of strategies have been tested for the management of RIF. In the light of the mechanisms described, a curative procedure has been proposed via the antioxidant pathway. In particular, it was showed that superoxide dismutase and combined pentoxifylline–tocopherol treatment enables the process of established radiation-induced fibroatrophy to be greatly reduced or even reversed, both in clinical practice and animal experiments. The efficacy of combined pentoxifylline–tocopherol treatment in superficial RIF was confirmed in a randomised clinical trial, and then in successful phase II trials especially in uterine fibroatrophy and osteoradionecrosis. It is of critical importance to evaluate these new management approaches in larger clinical trials and to improve the recording of results for better outcome analysis. Mechanistic studies are always necessary to improve understanding of the RIF process and the antifibrotic drug action.

Fred F Lange - One of the best experts on this subject based on the ideXlab platform.

  • effect of inclusions on Densification i microstructural development in an al2o3 Matrix containing a high volume fraction of zro2 inclusions
    Journal of the American Ceramic Society, 1992
    Co-Authors: Olivier Sudre, Fred F Lange
    Abstract:

    The microstructural changes produced by large (38 to 53 μm), single-crystal ZrO2 inclusions (0, 0.09, 0.30 volume fractions, based on solid volume) within an Al2O3 powder Matrix were detailed as a function of constrained Densification. Composite powder compacts were produced by pressure filtration for conditions where the Al2O3 slurry was either flocced or dispersed. For both conditions, the ZrO2 inclusions constrained Densification. Microstructural observations for all composites revealed (1) the presence of cracks with large opening displacements between inclusions and (2) large density variations within the Matrix. The cracks were most frequent at high volume fraction of inclusions in composites produced from flocced slurries and apparently originated during specimen preparation. Their large opening displacment was a result of Matrix Densification. Fewer cracks were observed in composites produced from dispersed slurries. Instead, these microstructures were dominated by large variations in Matrix density, viz., dense regions surrounding low-density regions, not consitent with the initial packing density of the Matrix powder. The denser regions were formed early in the Densification schedule. The lower-density regions eventually developed into regions containing large, elongated voids as the Al2O3 Matrix grains became larger with heat-treatment time. This pore enlargement process was shown to result from the disappearance of necks between originally sintered grains and appeared similar to the thermodynamic instability observed in thin films and constrained fibers.

Velu Saraswathy - One of the best experts on this subject based on the ideXlab platform.

  • estimation of the permeability of silica fume cement concrete
    Construction and Building Materials, 2010
    Co-Authors: Hawo Song, Sanghyeok Nam, Jongchul Jang, Seungwoo Pack, Velu Saraswathy
    Abstract:

    Abstract Deterioration and durability of concrete structures mainly depend on permeability of concrete. Silica fume (SF) as a mineral admixture for high performance concrete produces more discontinues and impermeable pore structure in concrete. The higher permeability reductions with silica fume are due to pore size refinement and Matrix Densification, reduction in content of Ca(OH)2 and cement paste-aggregate interfacial refinement. During the hydration process the transition interfacial zone is gradually densified due to pozzolanic reaction between silica fume and calcium hydroxide. Based on a microstructure model, a procedure for predicting the permeability of high strength silica fume cement concrete is developed by considering water-to-binder ratio, silica fume replacement ratio and degree of hydration as major influencing factors. Results of the permeability calculated using the procedure is verified with the available literature. Subsequently, effects of silica fume on the permeability of concrete are evaluated. Finally, optimum silica fume replacement ratios that reduce the permeability of concrete reasonably are proposed for durable concrete.

Olivier Sudre - One of the best experts on this subject based on the ideXlab platform.

  • effect of inclusions on Densification i microstructural development in an al2o3 Matrix containing a high volume fraction of zro2 inclusions
    Journal of the American Ceramic Society, 1992
    Co-Authors: Olivier Sudre, Fred F Lange
    Abstract:

    The microstructural changes produced by large (38 to 53 μm), single-crystal ZrO2 inclusions (0, 0.09, 0.30 volume fractions, based on solid volume) within an Al2O3 powder Matrix were detailed as a function of constrained Densification. Composite powder compacts were produced by pressure filtration for conditions where the Al2O3 slurry was either flocced or dispersed. For both conditions, the ZrO2 inclusions constrained Densification. Microstructural observations for all composites revealed (1) the presence of cracks with large opening displacements between inclusions and (2) large density variations within the Matrix. The cracks were most frequent at high volume fraction of inclusions in composites produced from flocced slurries and apparently originated during specimen preparation. Their large opening displacment was a result of Matrix Densification. Fewer cracks were observed in composites produced from dispersed slurries. Instead, these microstructures were dominated by large variations in Matrix density, viz., dense regions surrounding low-density regions, not consitent with the initial packing density of the Matrix powder. The denser regions were formed early in the Densification schedule. The lower-density regions eventually developed into regions containing large, elongated voids as the Al2O3 Matrix grains became larger with heat-treatment time. This pore enlargement process was shown to result from the disappearance of necks between originally sintered grains and appeared similar to the thermodynamic instability observed in thin films and constrained fibers.