Browsing by Author "Mohanty, Mira"

Now showing 1 - 6 of 6
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    Effect of 980-nm Diode Laser and 1064-nm Nd:YAG Laser on the Intervertebral Disc-In Vitro and in Vivo Studies
    (PHOTOMEDICINE AND LASER SURGERY, 2009)
    Objective: Our aim was to histologically evaluate the thermal changes in bovine intervertebral discs caused by 980-nm diode and 1064-nm Nd:YAG lasers. Further aims were to standardize the technique for in vivo animal research and to study its efficacy for clinical practice. Background: When conservative methods fail, surgery has so far been the only measure for severe back pain due to disc prolapse and herniation. Recently, the minimally invasive technique of laser disc decompression has become more popular because it has advantages over open surgery in properly selected cases. Methods: In vitro studies were done with Nd: YAG and diode lasers ( 1064 and 980 nm, respectively) on bovine intervertebral discs using a bare fiber tip or a focusing lens attached to a fiber tip. These studies were followed by in vivo studies in a canine model using a Nd: YAG laser with a bare fiber tip. Autopsies were done immediately and at 3, 6, 9, and 12mo after ablation and the histopathology of excised discs was evaluated. Results: Depending upon the depth of ablation and the intensity of charring and carbonization, a standardized energy density and pulse duration were identified. Conclusion: Nd: YAG laser with initial delivery of 40-W laser power and a reduced power of 10-15W thereafter, delivering a total energy density of 1500 2000J/cm(2) using a bare fiber tip, is recommended for clinical applications.
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    Hypoxia-Like Effect of Cobalt Chromium Alloy Micro Particles on Fibroblasts In Vitro
    (JOURNAL OF ORTHOPAEDIC RESEARCH, 2010)
    Periprosthetic osteolysis leading to asceptic loosening remains the primary cause of failure of Joint replacement Although many inflammatory cell types have been implicated, the exact pathomechanisms of asceptic loosening have not been delineated In the present study we have adopted a proteomic approach to elucidate the initial signals that are expressed to particulate material, using an in vitro cell culture system Human lung fibroblasts MRC-5 were cultured with Cobalt Chromium (CoCr ASTM F-75, 1-7 pm) particles Cells were harvested after 72 h incubation and total cellular proteins extracted for downstream analysis via 2D Gel Electrophoresis and tandem mass spectrometry using MALDI-TOF-TOF-MS Thirteen protein spots showed greater than twofold increase, following 72 h incubation of fibroblast with CoCr particles Four of these proteins were identified by tandem mass spectrometry These were Annexin II, Pyruvate kinase, Triose phosphate isomerase, and N-myc downstream regulated gene 1 protein Cobalt is a hypoxia mimicking agent and N-myc downstream regulated gene 1 protein, Triose phosphate isomerase, Pyruvate kinase, and Annexin II are important hypoxia regulated gene products that are found to be over expressed in cellular oxidative stress response Our data indicates that exposure of fibroblast to CoCr alloy induces the transition of these cells into a hypoxia like state and oxidative stress even in normoxic culture conditions The study reflects the possibility of the presence of a hypoxic environment in the periprosthetic tissue surrounding metallic implants (C) 2010 Orthopaedic Research Society Published by Wiley Periodicals, Inc J Orthop Res 28 1360-1367, 2010
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    Investigative Study of Myofibroblasts and Cytokines in Peri-Implant Tissue of Silicone Breast Expander by RT-PCR in a Rat Model
    (JOURNAL OF BIOMATERIALS SCIENCE-POLYMER EDITION, 2010)
    The excessive collagen deposition around silicone breast implants followed by contracture and development of severe pain is a major clinical problem. This study was conducted to investigate the profibrotic and antifibrotic cytokines secreted by inflammatory cells and development of myofibroblasts at the tissue material interface around silicone breast expander and ultra-high-molecular-weight polyethylene (UHMWPE). Both materials were implanted in rats for 30, 90 and 180 days. Inflammatory cells and collagen deposition at the material-tissue interface were assessed with Haematoxylin-Eosin and Masson's Trichrome stain. Gene expression of TGF beta, IL-1 beta, IFN gamma, IL10 and alpha-SMA was quantitated by real-time (RT)-PCR in the peri-implant tissue. Results indicate a difference in collagen deposition and myofibroblast development around both materials with involvement of TGF beta, IFN gamma and IL10. The results emphasise the need for further investigation into the molecular mechanisms of protomyofibroblast and myofibroblast formation around silicone implants, which would provide information on these target cells for inhibitory therapy in the clinical situation. (C) Koninklijke Brill NV, Leiden, 2010
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    Role of immune cells and inflammatory cytokines in regulation of fibrosis around silicone expander implants
    (JOURNAL OF MATERIALS SCIENCE-MATERIALS IN MEDICINE, 2010)
    This study aimed to investigate the progress of wound healing around silicone expander with particular emphasis on fibroblasts, myofibroblasts and collagen in the repair phase. Semi-quantitative evaluation of inflammatory cells and their cytokines, fibroblasts and myofibroblasts at the tissue-material interface was carried out. Commercially available silicone expander was implanted in gluteus muscle of young female Wistar rats for 3, 7, 14, 30, 90 and 180 days. Ultra high molecular weight polyethylene served as control. The cellular response was studied by immunohistochemistry and Transmission Electron Microscopy. A thick collagenous fibrous capsule was observed around the silicone expander at 180 days, with persistent myofibroblasts, lymphocytes and macrophages as compared to the thin fibrous encapsulation around the UHMWPE implants. The regulatory role of cytokines and immune cells in myofibroblast persistence in tissue-implant interface around silicone expander has been extensively studied. Results of this study indicate the need to elucidate the signaling molecules in the transition of fibroblast to myofibroblast around silicone expander implants.
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    Surface-Phosphorylated Copolymer Promotes Direct Bone Bonding
    (TISSUE ENGINEERING PART A, 2009)
    The bone bonding potential of surface-phosphorylated poly (2-hydroxyethyl methacrylate-co-methyl methacrylate) [poly (HEMA-co-MMA)] has been investigated and compared with commercially available poly (methyl methacrylate) bone cement (CMW1 radiopaque, Depuy; Johnson & Johnson, Blackpool, Lancashire, England, United Kingdom) as control. Poly (HEMA-co-MMA) is synthesized by free radical-initiated copolymerization and surface functionalized by phosphorylation. The X-ray photoelectron spectroscopy confirms the presence of surface-bound phosphate groups on poly (HEMA-co-MMA). The surface-phosphorylated poly (HEMA-co-MMA) promotes in vitro biomineralization, cell viability, cell adhesion, and expression of bone-specific markers such as osteocalcin and alkaline phosphatase. The bone implantation study performed in rabbits as per ISO 10993-6; 1994 (E) shows that surface-phosphorylated poly (HEMA-co-MMA) elicits bone bonding and new bone formation. New woven bone trabeculae are formed at the defect site of surface-phosphorylated poly (HEMA-co-MMA) within 1 week, while for control sample, inflammatory cells-predominantly, macrophages, fibroblasts, and fibrocytes-are present at the cortical margins around the defect. The 4 and 12 weeks postimplantation results show that the major part of the defects around the surface-phosphorylated poly (HEMA-co-MMA) implant is bridged with new woven bone, with significant remodeling (evident from resorption bays) along both the margins of the defect, but for control implants, the defects are only partially closed, with slight remodeling along the margins, but most of them are separated by fibrous tissue.
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    The reversal of diabetes in rat model using mouse insulin producing cells - A combination approach of tissue engineering and macroencapsulation
    (ACTA BIOMATERIALIA, 2011)
    Type 1 diabetes is a chronic disorder resulting from the autoimmune destruction of insulin-producing cells, a leading cause of morbidity and mortality all over the world. In this study a tissue engineering approach was compared with a macroencapsulation approach to reverse type 1 diabetes in a rat model. using mouse pancreatic progenitor cell (PPC)-derived islet-like clusters and mouse islets. For the tissue engineering approach the cells were cultured on gelatin scaffolds cross-linked with EDC in the presence of polyvinylpyrrolidone in vitro (GPE scaffolds), while for the macroencapsulation approach the cells were encapsulated in polyurethane-polyvinylpyrrolidone semi-Interpenetrating networks. In the combination approach the cells cultured on GPE scaffolds were further encapsulated in a polyurethane-polyvinylpyrrolidone capsule. Real time PCR studies and the glucose challenge assay have shown that cells on GPE scaffolds could express and secrete insulin and glucagon in vitro. However, under in vivo conditions the animals treated by the tissue engineering approach died within 15-20 days and showed no reversal of their diabetes, due to infiltration of immune cells such as CD4 and CD8 cells and macrophages. In the macroencapsulation approach the animals showed euglycemia within 25 days, which was maintained for further 20 days, but after that the animals died. Interestingly, in the combination approach the animals showed reversal of hyperglycemia, and remained euglycemic for up to 3 months. The time needed to achieve initial euglycemia was different with different cell types, i e. the combination approach with mouse Islets achieved euglycemia within 15 days, whereas with PPC-derived islet-like clusters euglycemia was achieved within 25 days This study confirmed that a combination of tissue engineering and macroencapsulation with mouse islets could reverse diabetes and maintain euglycemia in an experimental diabetes rat model for 90 days. (C) 2011 Acta Materialia Inc Published by Elsevier Ltd All rights reserved