Browsing by Author "Kumari, TV"

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    A novel thermoresponsive copolymer as a suitable substrate for tissue reconstruction
    (TISSUE ENGINEERING PART A, 2008) Viji, MV; Vidya, N; Hopkinson, A; Sreenivasan, K; Dua, HS; Kumari, TV
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    Cytocompatibility Studies of a Novel Bioactive Glass Coated Porous Hydroxyapatite Bioceramic for Use as a Bone Substitute
    (Key Engineering Materials., 2005) John, A; Varma, HK; Kumari, TV; Nisha, VR; Narayanan, D
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    Development and evaluation of a single solution bonding agent as a dental adhesive
    (JOURNAL OF POLYMER MATERIALS, 2005) Krishnan, VK; Lizymol, PP; Kumari, TV; Rauf, TA; Thomas, MM
    Development of a dentine bonding agent based on a tetramethacrylate resin with free carboxyl groups and its evaluation are described in this paper. Pyromellitic dianhydride was reacted with glycerol dimethactylate at 42-45 degrees C for 5 h in presence of an amine catalyst to produce a colorless and viscous pyromellitic anhydride-glycerol dimethacrylate adduct [PMGDM]. The resin was characterized using refractive index, infra red and NMR spectroscopy and HPLC chromatographic techniques. The resin was used to formulate a single solution bonding agent [SSBA] using acetone as the solvent, 2-hydroxyethyl methacrylate [HEMA] as the diluent, camphorquinone [CO] as the photoinitiator and dimethylamino phenethyl alcohol [DMAPEA] as the accelerator. Shear and tensile bond strengths of composites polymerized by photoinitiation adhered on dentinal and metallic surfaces using SSBA and an imported control Single Bond were evaluated and compared. Cytotoxicity evaluation by the MTT assay of SSBA and Single Bond on L-929 mammalian cell lines demonstrated metabolic activity of 1.7% of cells in contact with SSBA extract and 1.5% of cells in contact with Single Bond extract compared to 100% for cells alone. Shear and tensile strength evaluation at different intervals of time for the newly developed bonding agent stored at 22 +/- 2 degrees C upto 70 days showed no statistically significant variation in the strength values with time.
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    Development of non-toxic latex formulation for biomedical applications ( Project - 7003 )
    (SCTIMST, 2004-07-31) Mohanan, PV; Roy, Joseph; Ramesh, P; Mira, Mohanty; Kumari, TV
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    Effect of chronic inflammation and immune response on regeneration induced by decellularised bovine pericardium
    (JBMR Part A, 2016-08) Umashankar, PR; Arun, T; Kumari, TV
    Decellularised tissue produces a variety of host responses ranging from constructive remodeling to scarring on account of its differences in the source of tissue, processing or sterilization methods. In this study, in vivo regeneration induced by decellularised bovine pericardium with or without mild glutaraldehyde crosslinking was studied in relation to its immune and inflammatory response using rat abdominal regeneration model. Mild glutaraldehyde crosslinking was done to subdue inflammatory and immune response without compromising host cell incorporation and graft remodeling. Evaluations were done at both 21 and 90 days. Un-crosslinked decellularised bovine pericardium showed more intense macrophage response predominantly of M2 phenotype at 90 days indicating chronic inflammatory response compared to mildly crosslinked group. This group also showed significant increase in plasma cell and lymphocyte count indicating immune stimulation. Lymphocyte transformation test detected presence of bovine pericardial antigen sensitized lymphocytes at both periods in un-crosslinked group. Lymphocytes from mildly crosslinked group failed to respond in this test at both periods. Significantly higher antibody response was also noted at both periods in un-crosslinked group. However, abdominal wall regeneration was observed only in animals implanted with un-crosslinked decellularised bovine pericardium at 90 days. From the above findings, it is inferred that un-crosslinked decellularised bovine pericardium produced significant chronic inflammatory response at 90 days and stimulated both humoral and cell mediated immune response in comparison to mildly crosslinked decellularised bovine pericardium. Yet this group produced skeletal muscle formation within graft at 90 days.
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    Glutaraldehyde treatment elicits toxic response compared to decellularization in bovine pericardium.
    (Toxicology international, 2012)
    Glutaraldehyde-stabilized bovine pericardium is used for clinical application since 1970s because of its desirable features such as less immunogenicity and acceptable durability. However, a propensity for calcification is reported on account of glutaraldehyde treatment. In this study, commercially available glutaraldehyde cross-linked bovine pericardium was evaluated for its in vitro cytotoxic effect, macrophage activation, and in vivo toxic response in comparison to decellularized bovine pericardium. Glutaraldehyde-treated bovine pericardium and its extract were observed to be cytotoxic and it also caused significant inflammatory cytokine release from activated macrophages. Significant antibody response, calcification response, necrotic, and inflammatory response were noticed in glutaraldehyde-treated bovine pericardium in comparison to decellularized bovine pericardium in a rat subcutaneous implantation model. Glutaraldehyde-treated bovine pericardium also failed in acute systemic toxicity testing and intracutaneous irritation testing as per ISO 10993. With respect to healing and implant remodeling, total lack of host tissue incorporation and angiogenesis was noticed in glutaraldehyde-treated bovine pericardium compared to excellent host fibroblast incorporation and angiogenesis within the implant in decellularized bovine pericardium. In conclusion, using in vitro and in vivo techniques, this study has demonstrated that glutaraldehyde-treated bovine pericardium elicits toxic response compared to decellularized bovine pericardium which is not congenial for long-term implant performance.
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    In vitro cytocompatibility studies of Diamond Like Carbon coatings on titanium
    (BIO-MEDICAL MATERIALS AND ENGINEERING, 2002)
    Diamond Like Carbon (DLC) films were deposited on to titanium (Ti) substrates by Plasma Enhanced Chemical Vapour Deposition (PECVD) process. The quality of the films were checked by Raman spectra and nano-hardness tests. The cytocompatibility of titanium and DLC coated titanium were studied using continuous cell lines of mouse fibroblast cells (L-929), Human Osteoblast cells (HOS) and primary human umbilical cord vein endothelial cells (HUVEC). The cellular responses to the materials were assessed both quantitatively and qualitatively. The adhesion and spreading of cells on materials were compared using Ti as a control. Present study indicates an improved cytocompatibility of DLC coated Ti in comparison to bare Ti.
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    In vitro mineralization and cell adhesion on surface modified poly (2-hydroxy ethyl methacrylate-co-methyl methacrylate)
    (BIOCERAMICS 18, PTS 1 AND 2, 2006) Sailaja, GS; Kumari, TV; Yokogawa, Y; Varma, HK
    Poly(2-hydroxyethyl methacrylate-co- methyl methacrylate) HM, was synthesized by free radical copolymerization, cross-linked with ethylene glycol dimethacrylate and phosphorylated. The phosphate coupling was ensured by ATR spectroscopy. The in vitro mineralization ability of the phosphorylated HM (designated as PHM) was investigated by studying the nucleation and growth of calcium phosphate on its surface by immersing in simulated body fluid (SBF) solution. The coating morphology was studied by SEM and the Ca/P ratio of the coating by EDX analysis. The cell adhesion behaviour of PHM was studied by seeding Human osteosarcoma (HOS) cells for one week followed by SEM analysis along with HM as control. It was observed that HOS cells exhibited biomineralization of calcium phosphate on the surface of HM as well as on PHM with a significantly higher amount on the surface of PHM as observed by von kossa staining method. The results show that PHM is capable of in vitro mineralization under simulated physiological condition, promotes cell adhesion by providing an excellent cell friendly surface and it exhibits biomineralization of calcium phosphate in presence of HOS cells.
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    In vitro studies on the effect of physical cross-linking on the biological performance of aliphatic poly(urethane urea) for blood contact applications
    (BIOMACROMOLECULES, 2001)
    The effect of physical cross-Linking in candidate cycloaliphatic and hydrophobic poly(urethane urea) (4,4'-methylenebis(cyclohexylisocyanate), H12MDI/hydroxy-terminated polybutadiene, HTPBD/hexamethylene-diamine, HDA) and poly(ether urethane urea)s (H12MDI/HTPBD-PTMG/HDA) on the in vitro calcification and blood-material interaction was studied. All the candidate poly(urethane urea)s and poly(ether urethane urea)s elicit acceptable hemolytic activity, cytocompatibility, calcification, and blood compatibility in vitro. The studies on blood-material interaction reveal that the present poly(urethane urea)s are superior to polystyrene microtiter plates which were used for the studies on blood-material interaction. The present investigation reveals the influence of physical cross-link density on biological interaction differently with poly(urethane urea) and poly(ether urethane urea)s. The higher the physical cross-link density in the poly(urethane urea)s, the higher the calcification and consumption of WBC in whole blood. On the other hand, the higher the physical cross-link density in the poly(ether urethane urea)s, the lesser the calcification and consumption of WBC in whole blood. However a reverse of the above trend has been observed with the platelet consumption in the poly(urethane urea)s and poly(ether urethane urea)s.
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    Preliminary in vitro and in vivo characterization of a sol-gel derived bioactive glass
    (Bulletin of Materials Science., 2002) Abiraman, S; Varma, HK; Kumari, TV; Umashankar, PR; John, A
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    Preliminary in vitro and in vivo characterizations of a sol-gel derived bioactive glass-ceramic system
    (BULLETIN OF MATERIALS SCIENCE, 2002) Abiraman, S; Varma, HK; Kumari, TV; Umashankar, PR; John, A
    This study investigates quantitatively and qualitatively the sol-gel derived bioactive glass-ceramic system (BGS)-apatite-wollastonite (AW) type granules in the size range of 0.5-1 mm, as an effective graft material for bone augmentation and restoration. Scanning electron micrographs (SEM) of the sintered granules revealed the rough material surface with micropores in the range 10-30 mum. X-ray diffraction (XRD) pattern of the granules revealed the presence of crystalline phases of the hydroxyapatite and wollastonite, and the functional groups of the silicate and phosphates were identified by Fourier transform infrared spectroscopy (FT-IR). The in vitro cell culture studies with L929 mouse fibroblast cell line showed very few cells adhered on the BGS disc after 24 h. This could be due to the highly reactive surface of the disc concomitant with the crystallization but not due to the cytotoxicity of the material, since the cellular viability (MTT assay) with the material was 80%. Cytotoxicity and cytocompatibility studies proved that the material was non-toxic and biocompatible. After 12 weeks of implantation of the BGS granules in the tibia bone of New Zealand white rabbits, the granules were found to be well osteointegrated, as observed in the radiographs. Angiogram with barium sulphate and Indian ink after 12 weeks showed the presence of micro capillaries in the vicinity of the implant site implicating high vascularity. Gross observation of the implant site did not show any inflammation or necrosis. SEM of the implanted site after 24 weeks revealed good osteointegration of the material with the newly formed bone and host bone. New bone was also observed within the material, which was degrading. Histological evaluation of the bone healing with the BGS granules in the tibial defect at all time intervals was without inflammation or fibrous tissue encapsulation. After 2 weeks the new bone was observed as a trabeculae network around the granules, and by 6 weeks the defect was completely closed with immature woven bone. By 12 weeks mature woven bone was observed, and new immature woven bone was seen within the cracks of the granules. After 24 weeks the defect was completely healed with lamellar bone and the size of the granules decreased. Histomorphometrically the area percentage of new bone formed was 67.77% after 12 weeks and 63.37% after 24 weeks. Less bone formation after 24 weeks was due to an increased implant surface area contributed by the material degradation and active bone remodeling. The osteostimulative and osteoconductive potential of the BGS granules was established by tetracycline labelling of the mineralizing areas by 2 and 6 weeks. This sol-gel derived BGS granules proved to be bioactive and resorbable which in turn encouraged active bone formation.
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    Surface reactivity of calcium phosphate based ceramics in a cell culture system
    (JOURNAL OF BIOMATERIALS APPLICATIONS, 2003)
    Surface reactivity of Calcium Phosphate materials - Hydroxyapatite (RA), Tricalcium. Phosphate (beta-TCP), Hydroxyapatite-Tricalcium Phosphate (HA-TCP) were elucidated in a cell culture system. MG-63 osteoblast-like cells were seeded onto the ceramic discs to evaluate changes in the cell morphology and functionality with respect to the different substrates.The dissolution and re-precipitation of calcium phosphate phases on the surface of the discs in the culture medium was found to be prominent on beta-TCP when compared with HA. Low calcium (Ca), magnesium (Mg) and alkaline phosphatase (ALP) levels and high phosphorous (P) levels in the medium of,beta-TCP were observed. This indicated that P must have leached out into the medium from beta-TCP and Ca in turn deposited from the medium onto beta-TCP resulting in the apatite phase transformation. The low ALP activity in beta-TCP medium is however an indication of low osteoblastic activity.Under the phase contrast microscope, the osteoblast cells around RA material were found to be confluent and viable, while in the vicinity of beta-TCP only cellular debris was observed. In the case of RA-TCP, only a few viable cells surrounded the material amidst the debris. Scanning electron microscopy revealed numerous cells on the surface of HA showing different cell behaviour like anchorage, attachment, adhesion and spreading in the early time period as the surface was only slightly disturbed with re-crystallisation. But with time the entire surface of HA had changed due to precipitation and re-crystallization which did not support cell behaviour while the cells surrounding the material showed normal growth. On the contrary, cells were scarcely observed on the entirely changed surface of beta-TCP and RA-TCP even from the earlier days of the culture and the morphology of cells surrounding the material too started changing.These results establish that HA promoted the activity of osteoblast cells. HA surface remained unaltered for some time, while the surface of beta-TCP underwent dissolution of surface ions and resulted in the re-crystallization of apatite over the surface. The resulting changes in the surrounding milieu of beta-TCP with high phosphate and low Ca levels probably was responsible for the death of the cells.