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Biomedical subjects

P R Hari

Publications and source records attributed to P R Hari.

12 recordsLinked to original sources
PubMed2000

Adsorption of human IgG on Cu(2+)-immobilized cellulose affinity membrane: preliminary study.

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 Cu(2+) ion-immobilized cellulose membrane. Although Cu(2+) ligand is selective to IgG, in general gamma-globulins also are adsorbed. The simplicity and lower cost of Cu(2+) ion-immobilized cellulose membranes may be useful for removing IgG from blood.

Antibody Affinity↗
PubMed1997

Modified polyacrylamide microspheres as immunosorbent.

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 C3 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.

Acrylic Resins↗
PubMed1996

Development of silastic polyurethane (Angioflex) materials with antibacterial agent.

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 8r synergistic antibacterial effects with chlorhexidine digluconate coated Angioflex material.

Anti-Bacterial Agents↗
PubMed1993

Protein adsorption--effect of external lubricants at the interface.

Upon exposure to blood, rapid adsorption of proteins is the initial event at the contacting surface, followed by the adhesion of platelets and other blood components. Surfaces absorbing albumin appear to possess antithrombotic character in discouraging adhesion of platelets. Therefore, for the development of a blood contacting device, the interfacial events are extremely important and need serious investigation. We have attempted to observe the variations in competitive adsorption of fibrinogen and albumin onto the polyetherurethane urea (PEUU) surface in the presence of external lubricant, such as calcium stearate and silicone fluid coating. It seems, in the presence of such mediators, that fibrinogen adsorption is increased relatively with reduction in albumin at the surface.

Adsorption↗
PubMed1993

Hydrogen grafted polymer surfaces: interaction and morphology of platelets.

Besides the quantification of platelet adhesion, the morphology of adherent platelets on a polymer surface seems to be important as far as thrombogenicity is concerned. It is suggested that such events usually take place on a layer of adsorbed proteins on the surface of the blood. In the present study, we observed the morphological variation of adherent calf platelets (in vitro under static conditions) on bare and hydrogel-grafted Angioflex sheets. Electron micrographs indicate the extent of deformation of the Angioflex sheets varying with modified substrates as compared to the bare sheets.

Animals↗
PubMed1991

Adhesion and stability of blood cells onto polymer substrates: effect of glow discharge.

The adhesion of platelets, red blood cells, and lymphocytes onto various polymer substrates, hydrophobic to hydrophilic in nature, has been studied. Cell adhesion is found to be higher on hydrophilic substrates. The stability of these adhered cells has also been studied under a flow rate of 20 ml/min. Further the effect of glow discharge treatment onto various substrates is investigated. It seems the stability is more on glow discharge treated substrates due to increased surface free energy.

Animals↗
PubMed1991

Hydrogel grafted surfaces: protein interaction and platelet adhesion.

The blood compatibility of an artificial polymeric implant largely depends on the physicochemical nature of the polymer substrate. In the present study our aim is to develop an understanding of polymer surfaces having similar surface free energy, but different chemical characteristics. We attempted to graft hydrogels onto a silastic polyurethane (Angioflex) material and optimised the surface free energy to about 35.0 ergs/cm2. We compared the protein adsorption and platelet and lymphocyte adhesion on these surfaces. It is observed that there is a relative change in behavior because of the difference in chemical nature.

Adsorption↗
PubMed1991

The effect of anesthetics and analgesics on protein adsorption, platelet adhesion, and plasma recalcification time at blood-polymer interface.

Protein adsorption and subsequent cellular reactions are important biological events at the blood-polymer interface. Mediators like drugs, vitamins, and steroid hormones play a significant role in protein adsorption. An attempt is made to understand the effect of several i.v. agents on protein-platelet interaction with an artificial surface, polycarbonate. Pentothal, an anesthetic; lignocaine, a local anesthetic; pethidine, a narcotic anesthetic; Calmpose, a tranquilizer; and Novalgin, an analgesic, were drugs used for this study. Competitive adsorption of proteins is evaluated using a trace-labeled technique from a mixture of proteins (25 mg/dl of albumin, 15 mg/dl of tau-globulin, and 7.5 mg/dl of fibrinogen). Platelet and lymphocyte adhesion and plasma recalcification time are studied from calf blood. It is observed that these agents modulate the protein and cellular interaction and also the blood coagulation time. Therefore, proper selection of such including agents should not be overlooked for an implant surgery or while ministering to a patient with an implant.

Adsorption↗
PubMed1990

Grafting of synthetic polyelectrolyte onto polymer surfaces--comparison of glow discharge and 60Co-gamma-irradiation method.

Water soluble polyelectrolyte synthesised from natural rubber contains sulfamate and carboxylate groups similar to that of heparin. It is observed that synthetic heparinoid polyelectrolyte is capable of inhibiting blood coagulation. In the present study, we attempted to graft the same onto polystyrene and polymethylmethacrylate surfaces using glow discharge technique and 60Co-gamma-irradiation method, and the surfaces were compared with respect to water contact angle and platelet adhesion parameters. Heparinised surfaces are also evaluated for relative comparison.

Animals↗
PubMed1990

Surface modification of polystyrene--platelet adhesion.

Indomethacine is an analgesic and antiinflammatory drug which has antiplatelet and antithrombotic properties. In our work, we have tried to immobilize the same onto a polymer surface covalently. Surface parameters like water contact angle and platelet adhesion are studied. Similar studies are conducted on heparin immobilized surfaces, for relative comparison.

Albumins↗
PubMedDate not supplied

Chitosan/calcium alginate microcapsules for intestinal delivery of nitrofurantoin.

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-CaCl(2) 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.

Administration, Oral↗