Browsing by Author "Hari, PR"

Now showing 1 - 12 of 12
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    Adsorption of human IgG on Cu2+-immobilized cellulose affinity membrane: Preliminary study
    (JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, 2000)
    Immobilized metal ion affinity chromatography (IMAC) is widely used. Transition metal ions have a high affinity to some peptide sequences. We have studied the selective adsorption of human IgG from a mixture of albumin, gamma-globulin, fibrinogen, and IgG onto Cu2+ ion-immobilized cellulose membrane. Although Cu2+ ligand is selective to IgG, in general gamma-globulins also are adsorbed. The simplicity and lower cost of Cu2+ ion-immobilized cellulose membranes may be useful for removing IgG from blood. (C) 2000 John Wiley & Sons, Inc.
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    Chitosan/calcium alginate microcapsules for intestinal delivery of nitrofurantoin
    (JOURNAL OF MICROENCAPSULATION, 1996)
    A new sustained-release dosage form of nitrofurantoin (NF) as microcapsules has been prepared by a mild chitosan/calcium alginate microencapsulation process. These microcapsules have been prepared by adding, dropwise, a solution of sodium alginate containing NF into a chitosan-CaCl2 system. About 70-80% of the drug is released into phosphate buffer, pH = 7.4 within 6 h. Drug release into the gastric medium is found to be relatively slow compared to that into the intestinal medium. From scanning electron microscopic studies, it appears that the chitosan modifies the NF-alginate microspheres. These findings suggest the possibility of modifying the formulation to obtain the controlled release of NF in an oral sustained-delivery system.
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    Chitosan/calcium-alginate beads for oral delivery of insulin
    (JOURNAL OF APPLIED POLYMER SCIENCE, 1996) Hari, PR; Chandy, T; Sharma, CP
    A mild chitosan/calcium alginate microencapsulation process, as applied to encapsulation of biological macromolecules such as albumin and insulin, was investigated. The microcapsules were derived by adding dropwise a protein-containing sodium alginate mixture into a chitosan-CaCl2 system. The beads containing a high concentration of entrapped bovine serum albumin (BSA) as more than 70% of the initial concentration were achieved via varying chitosan coat. It was observed that approximately 70% of the content is being released into Tris-HCl buffer, pH 7.4 within 24 h and no significant release of BSA was observed during treatment with 0.1M HCl pH 1.2 for 4 h. But the acid-treated beads had released almost all the entrapped protein into Tris-HCl pH 7.4 media within 24 h. Instead of BSA, the insulin preload was found to be very low in the chitosan/calcium alginate system; the release characteristics were similar to that of BSA. From scanning electron microscopic studies, it appears that the chitosan modifies the alginate microspheres and subsequently the protein loading. The results indicate the possibility of modifying the formulation in order to obtain the desired controlled release of bioactive peptides (insulin), for a convenient gastrointestinal tract delivery system. (C) 1996 John Wiley & Sons, Inc.
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    Development of silastic polyurethane (Angioflex) materials with antibacterial agent
    (JOURNAL OF BIOMATERIALS APPLICATIONS, 1996)
    Bioimplants incorporated with antimicrobial agents are needed to control Foreign Body Associated Infection (FBAI) in clinical settings. Attempts are made here to develop five different types of polyurethane (Angioflex), viz., (1) bare polymer, (2) bare polymer glow discharged, (3) bare polymer coated with chlorhexidine, (4) chlorhexidine coated polymer glow discharged, and (5) material (4) recoated with another layer of chlorhexidine digluconate. These materials are tested for their in vitro antibacterial effects using disc diffusion technique against five different standard clinical staphylococcus strains, viz., Wood 46 (Staph. aureus), A 182 (Staph. epidermidis), A 313 (Staph. epidermidis), A 61 (Staph. epidermidis), and A 72 (Staph. epidermidis). Maximum antibacterial effects (zone of inhibition) are observed with polyurethanes incorporated with chlorhexidine digluconate (3) and chlorhexidine incorporated and glow discharged (4). Findings of this study indicate that glow discharge does not seem to produce either additive or synergistic antibacterial effects with chlorhexidine digluconate coated Angioflex material.
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    Effect of blood flow on drug release from DES: An experimental study
    (INTERNATIONAL JOURNAL OF CARDIOLOGY, 2009) Umashankar, PR; Hari, PR; Sreenivasan, K
    DES has made stenting a successful treatment modality. Still problems exists such as late thrombosis and continued neo-intimal proliferation. Blood flow affects the drug retained in the stent and subsequently on the time frame of vascular healing. To find out drug release kinetics from DES implanted in two different flow conditions, DES were implanted in porcine carotid artery and coronary artery. The drug release kinetics was found out by estimating the drug retained in the stent at different time periods. Through this study it is shown that DES in the coronary artery has a T1/2 of 24 days compared to 2 days in the carotid artery. The difference in T1/2 is attributed to the difference in flow as estimated using Hagen - Poiseuille equation. Evaluation of DES through heterotopic implantation may yield false results due to flow discrepancy. Moreover flow conditions should also be considered while designing the drug matrix to have optimum clinical efficacy. (C) 2007 Elsevier Ireland Ltd. All rights reserved.
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    Glutathione-bearing fluorescent polymer-curcumin conjugate enables simultaneous drug delivery and label-free cellular imaging
    (Polymer, 2015-09) Dey, S; Ambattu, LA; Hari, PR; Rekha, MR; Sreenivasan, K
    Curcumin is a natural polyphenol with potential anticancer property. However, the medicinal assets of curcumin cannot be properly utilized due to its low aqueous solubility, instability and subsequent poor bioavailability. Conjugation of curcumin to a suitable hydrophilic polymer is a useful approach for augmenting the aqueous solubility of the drug. In addition, nano-structured materials with intrinsic fluorescence property are of prime importance in the current biomedical domain. In this study, a novel glutathione containing biodegradable, non-toxic and water soluble, fluorescent polymer was developed. Curcumin was covalently conjugated to this polymer to fabricate nano-sized micelle forming fluorescent polymer-curcumin conjugate. The ability of the entity as a safer curcumin delivery vehicle and label-free cellular imaging probe was demonstrated in C6 glioma cells.
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    Modified polyacrylamide microspheres as immunosorbent
    (ARTIFICIAL CELLS BLOOD SUBSTITUTES AND IMMOBILIZATION BIOTECHNOLOGY, 1997)
    Extracorporeal immunoadsorption system has been used for the specific removal of immunologically active substances from the blood. In this study, an attempt is made to utilise polyacrylamide microspheres as a matrix for immunoadsorption. Phenyl alanine is coupled onto the polymer beads using glutaraldehyde. These modified beads exhibit a high binding affinity for gamma-globulin compared to bare beads. The surface modified ones showed selective adsorption of immunoglobulins of IgG class. The C-3 adsorption pattern is not altered significantly upon modification. Modified beads are found to be less hemolytic after modification. However, more studies are to be conducted for the development of a hemoperfusion column based on this modified matrix.
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    Preparation of polyvinyl alcohol hydrogel through the selective complexation of amorphous phase
    (JOURNAL OF APPLIED POLYMER SCIENCE, 2001) Hari, PR; Sreenivasan, K
    Several methods for the preparation of polyvinyl alcohol (PVA) hydrogel are being reported in the literature. In this communication a new, simple, and mild complexation reaction using phenyl boronic acid, leading to a highly elastic PVA hydrogel, is addressed. It is found that the inherent crystalline property of the semicrystalline PVA is retained by the complexation reaction, which is confined to the amorphous region. An enhanced mechanical property, particularly in the wet condition, is observed after the modification resulting from the intact crystallinity. Also, the inherent nontoxic characteristic property of PVA is unaffected upon this complexation reaction. (C) 2001 John Wiley & Sons, Inc.
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    Selective estimation of C-reactive protein in serum using polymeric formulations without antibody
    (SENSORS AND ACTUATORS B-CHEMICAL, 2010) Raj, V; Hari, PR; Antony, M; Sreenivasan, K
    A new method without employing antibody for the estimation of C-reactive protein (CRP) in serum is presented. The method centres on the variation of fluorescence intensity of pair copolymers, containing a fluorophore (Fluoreseinamine isomer 1) and O-Phosphorylethanolamine (PEA), a ligand of CRP. We found that the fluorescence of fluorophore attached copolymer was quenched in the presence of copolymer conjugated with PEA. The fluorescence emission was, however, increased when CRP was added into the solution of the copolymers. The intensity of fluorescence increased linearly up to a concentration of 250 ng/mL of CRP and then attained a constant value which remains the same with additional quantity of CRP. This observation was assigned to the saturation of the binding sites. Other proteins namely, albumin, fibrinogen and globulin did not show any interference in the measurement. The method was used for the estimation of CRP in blood serum of patients reported to the cardiology and the data compared well with the quantity of CRP in the same samples estimated using immunoassay method. Our results suggest that the polymer pick up CRP selectively from a complex milieu like serum. The method is simple, cost effective and sensitive with a detection limit of 20 ng/mL. (C) 2010 Elsevier B.V. All rights reserved.
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    Simultaneous determination of homocysteine and asymmetric dimethylarginine in human urine by liquid chromatography-tandem mass spectrometry
    (JOURNAL OF CHROMATOGRAPHY B-ANALYTICAL TECHNOLOGIES IN THE BIOMEDICAL AND LIFE SCIENCES, 2013) Gopu, CL; Hari, PR; George, R; Harikrishnan, S; Sreenivasan, K
    Increased circulating concentrations of homocysteine (HCY) and asymmetric dimethylarginine (ADMA) are associated with vascular disease and vascular risk factors. HCY has been shown to inhibit the activity of endothelial dimethylaminohydrolase (DDAH), causing the accumulation of ADMA and the inhibition of nitric oxide synthesis. The concentrations of HCY and ADMA in biological fluids are used in the clinical diagnosis of cardiovascular diseases and this necessitates the development of a rapid and sensitive method for simultaneous determination of HCY and ADMA. A rapid, simple and sensitive method for simultaneous determination of HCY and ADMA by liquid chromatography-tandem mass spectrometry (LC-MS/MS) coupled with electro spray ionization (ESI) in human urine was reported here. The methodology designed here was used to estimate these molecules in urine samples collected from patients reported to Cardiology Department of our hospital. Chromatographic separation was performed on Atlantis HILIC silica (100 mm x 2.1 mm, 5 mu m, Waters). Positive multiple reactions monitoring (MRM) mode was chosen for quantification of each analyte and cystamine dihydrochloride (CYA) was used as the internal standard (IS) for the assay. The intra-assay precision and accuracy were in the range of 2.4-4.8 and -1.8% to 3.1%, respectively. The inter-assay precision and accuracy were in the range of 3.0-4.2% and -1.2% to 3.2%, respectively. The recoveries were between 94.9% and 101.4%. Our approach is simple, rapid and could be extended to routine urine assay. (C) 2013 Elsevier B.V. All rights reserved.
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    Simultaneous determination of homocysteine and asymmetric dimethylarginine in human urine by liquid chromatography–tandem mass spectrometry
    (J. Chromatogr B., 2013-10) Gopu, GL; Hari, PR; George, R; Harikrishnan, S; Sreenivasan, K