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Abu Bakr Sayf Aldin. Qutayshat - One of the best experts on this subject based on the ideXlab platform.

Hiran Perinpanayagam - One of the best experts on this subject based on the ideXlab platform.

  • Cellular Response to mineral trioxide aggregate root-end filling materials.
    Journal (Canadian Dental Association), 2009
    Co-Authors: Hiran Perinpanayagam
    Abstract:

    Endodontic surgical procedures involve the use of a root-end filling material to provide an apical seal and to facilitate the repair and regeneration of periradicular tissues. Whereas earlier studies typically evaluated the cytotoxicity of these materials, contemporary research has focused on their capacity to support a favourable Cellular Response. In vitro tissue culture techniques have demonstrated interactions at the cell surface that may be conducive to periapical healing. Recent research with osteoblasts has confirmed their affinity for novel endodontic mineral trioxide aggregate (MTA) materials, with evidence of cell attachment and synthesis of bone matrix. This article reviews the current state of knowledge about MTA as a root-end filling material, with particular emphasis on Cellular Response to MTA materials.

Herbert Hönigsmann - One of the best experts on this subject based on the ideXlab platform.

  • STRESS PROTEINS IN THE Cellular Response TO ULTRAVIOLET RADIATION
    Journal of photochemistry and photobiology. B Biology, 1996
    Co-Authors: Franz Trautinger, Ingela Kindås-mügge, Robert Knobler, Herbert Hönigsmann
    Abstract:

    Abstract Virtually all cells — from prokaryotes to highly differentiated mammalian tissues — respond to a sudden increase in temperature with increased production of a limited set of proteins, called heat shock proteins or stress proteins (hsp). Other stress factors such as alcohol, heavy metals, oxidants and agents leading to protein denaturation are equally able to induce a similar Response. Induction of hsp is followed by a transient state of increased resistance to further stress. Many hsp function as “molecular chaperones” by binding to partially folded or misfolded proteins thus preventing their irreversible denaturation during stress. The high evolutionary conservation of this reaction suggests its importance for the survival of cells and tissues under hostile environment conditions. Ultraviolet radiation (UV) exerts many potentially harmful effects on prokaryotic and eukaryotic cells and hsp may help the cell to cope with UV-induced damage. This review will focus on the role of hsp in the Cellular Response of mammalian skin to UV. Hsp have been detected in resting as well as stress exposed epidermal and dermal cells and experimental evidence points to the fact that these proteins mediate protection from UV induced cell death in vitro and in vivo. Experimental studies further indicate that UV itself might be able to induce the expression of specific hsp. Thus, hsp might provide an adaptive Cellular Response to increasing exposure to UV. Furthermore, UV-activation of hsp synthesis may provide a valuable model for investigation of the transcription regulation of UV-induced gene expression.

Travis H Stracker - One of the best experts on this subject based on the ideXlab platform.

  • the Cellular Response to dna double strand breaks defining the sensors and mediators
    Trends in Cell Biology, 2003
    Co-Authors: John H J Petrini, Travis H Stracker
    Abstract:

    The induction of DNA double-strand breaks (DSBs) culminates in the activation of cell cycle checkpoint Responses and DNA repair machinery. The mechanism of DSB detection remains unclear although many candidate sensor proteins have been identified through cytologic, biochemical and genetic studies. In light of recent advances in our understanding of the Cellular Response to DSBs, we have proposed criteria for defining sensor proteins. We discuss the possible role of the Mre11 complex as a primary damage sensor and the complex relationship between DNA damage sensors, transducers and mediators.

Robert E. Guldberg - One of the best experts on this subject based on the ideXlab platform.

  • Do Surface Porosity and Pore Size Influence Mechanical Properties and Cellular Response to PEEK?
    Clinical Orthopaedics and Related Research®, 2016
    Co-Authors: F. Brennan Torstrick, Nathan T. Evans, Hazel Y. Stevens, Ken Gall, Robert E. Guldberg
    Abstract:

    Background Despite its widespread use in orthopaedic implants such as soft tissue fasteners and spinal intervertebral implants, polyetheretherketone (PEEK) often suffers from poor osseointegration. Introducing porosity can overcome this limitation by encouraging bone ingrowth; however, the corresponding decrease in implant strength can potentially reduce the implant’s ability to bear physiologic loads. We have previously shown, using a single pore size, that limiting porosity to the surface of PEEK implants preserves strength while supporting in vivo osseointegration. However, additional work is needed to investigate the effect of pore size on both the mechanical properties and Cellular Response to PEEK. Questions/purposes (1) Can surface porous PEEK (PEEK-SP) microstructure be reliably controlled? (2) What is the effect of pore size on the mechanical properties of PEEK-SP? (3) Do surface porosity and pore size influence the Cellular Response to PEEK? Methods PEEK-SP was created by extruding PEEK through NaCl crystals of three controlled ranges: 200 to 312, 312 to 425, and 425 to 508 µm. Micro-CT was used to characterize the microstructure of PEEK-SP. Tensile, fatigue, and interfacial shear tests were performed to compare the mechanical properties of PEEK-SP with injection-molded PEEK (PEEK-IM). The Cellular Response to PEEK-SP, assessed by proliferation, alkaline phosphatase activity, vascular endothelial growth factor production, and calcium content of osteoblast, mesenchymal stem cell, and preosteoblast (MC3T3-E1) cultures, was compared with that of machined smooth PEEK and Ti6Al4V. Results Micro-CT analysis showed that PEEK-SP layers possessed pores that were 284 ± 35 µm, 341 ± 49 µm, and 416 ± 54 µm for each pore size group. Porosity and pore layer depth ranged from 61% to 69% and 303 to 391 µm, respectively. Mechanical testing revealed tensile strengths > 67 MPa and interfacial shear strengths > 20 MPa for all three pore size groups. All PEEK-SP groups exhibited > 50% decrease in ductility compared with PEEK-IM and demonstrated fatigue strength > 38 MPa at one million cycles. All PEEK-SP groups also supported greater proliferation and cell-mediated mineralization compared with smooth PEEK and Ti6Al4V. Conclusions The PEEK-SP formulations evaluated in this study maintained favorable mechanical properties that merit further investigation into their use in load-bearing orthopaedic applications and supported greater in vitro osteogenic differentiation compared with smooth PEEK and Ti6Al4V. These results are independent of pore sizes ranging 200 µm to 508 µm. Clinical Relevance PEEK-SP may provide enhanced osseointegration compared with current implants while maintaining the structural integrity to be considered for several load-bearing orthopaedic applications such as spinal fusion or soft tissue repair.