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Biomedical subjects

C P Sharma

Publications and source records attributed to C P Sharma.

At least 109 records · Page 6Linked to original sources
PubMedDate not supplied

The antithrombotic effect of prostaglandin E1 immobilized on albuminated polymer matrix.

For intravascular implantation, a biofunctional surface seems to retard surface thrombosis upon synthetic materials. Prostaglandins, like PGI2, PGE1, and PGD2, etc., are believed to stimulate membrane-bound adenyl cyclase and thereby raise intracellular levels of c-AMP within platelets, which inhibit platelet adhesion and aggregation. A new procedure is suggested for the immobilization of prostaglandin E1 on an albuminated polymer matrix, through glutaraldehyde coupling. Materials thus prepared show dramatic antiplatelet effects, with regard to platelet adhesion, when compared with albumin-immobilized surfaces. The affinity of various modified surfaces toward platelet adhesion is studied, using washed platelets suspended in Tyrode's solution. Octane contact angle studies are used to develop an understanding of the varied nature of bound substrates at equilibrium on polymer surfaces. These are studied at the solid/liquid interface, which is closest to in vivo conditions. The plasma recalcification time demonstrates the anticoagulant properties of various surfaces. A possible role of PGE1 in reducing platelet activity in the presence and absence of vitamin C is discussed. This technique may be used in the development of non-thrombogenic surfaces on existing biomedical polymers. Simultaneous pharmaceutical modification of the blood with vitamin C may enhance the blood compatibility of the surface.

Albumins↗
PubMedDate not supplied

Lipoinsulin encapsulated alginate-chitosan capsules: intestinal delivery in diabetic rats.

An oral formulation based on liposome encapsulated alginate-chitosan gel capsules was developed for insulin delivery for the treatment of diabetes. Liposome encapsulation helped to increase the encapsulation efficiency of insulin in alginate-chitosan capsules. This formulation delivers insulin in the neutral environment of the intestine, by-passing the acidic media in the stomach, with increased drug absorption and bioavailability. Oral administration of this formulation was found to reduce blood glucose levels when tested in diabetic rats.

Administration, Oral↗
PubMedDate not supplied

In vivo absorption studies of insulin from an oral delivery system.

Alginate microspheres prepared by an emulsion-based process were loaded with insulin by a remote loading process. We observed that the time of exposure, pH of the remote loading medium, and beta-cyclodextrin complexation of insulin influenced drug loading. In vivo absorption studies of insulin from optimized microspheres were carried out in diabetic albino rats. Serum sugar levels on administration of multiple oral doses of the microspheres and a radioimmunoassay for serum insulin indicated absorption of insulin from the gastrointestinal region. This process could be utilized for the development of an oral insulin delivery system.

Administration, Oral↗
PubMedDate not supplied

Soluble substituted poly-p-phenylenes--a new material for application in light-emitting diodes: synthesis and characterization.

Poly-p-phenylenes have attracted a great deal of attention with respect to their applications in displays, light-emitting devices, and batteries. However, the polymer poly-p-phenylene obtained by the Kovacic method is insoluble and intractable. The present study reports the preparation of soluble poly(p-phenylenes) by polymerization of derivatives of benzene in the presence of a specific aromatic nuclei. The resultant copolymer so obtained is soluble in common organic solvents such as chloroform and toluene. Preliminary studies have indicated that the polymer shows orange photoluminescence and electroluminescence when a potential of 7-10 V is applied to the device.

Chloroform↗
PubMedDate not supplied

Preparation and performance of chitosan encapsulated activated charcoal (ACCB) adsorbents for small molecules.

A technique is described to encapsulate activated charcoal for haemoperfusion to be used in an artificial liver support. Activated charcoal was encapsulated within chitosan matrix (ACCB) in different concentrations, and was used as the supports for perfusion of a mixture of solutes, having molecular weight ranges from 60 to 69,000; under a flow rate of 8 ml/min. It seems the ACCB may be a good adsorbent system for the removal of toxic uric acid, creatinine, bilirubin, etc., from solutions; while larger molecules such as albumin are adsorbed less. The encapsulated charcoal did not leach out from the matrix during perfusion, and the system may be useful for detoxification of blood. The haemolytic potential of ACCB has been compatible with polystyrene control tubes. However, further studies are needed to determine their behaviour under clinical conditions.

Adsorption↗
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↗
PubMedDate not supplied

Surface--interface energy contributions to blood compatibility.

An attempt has been made to understand and correlate surface - and interface energy parameters with the blood compatibility of an implant surface. Although, it is realized that such concepts alone may not be enough to explain the complex multiparameter processes of such interactions at the interface.

Adsorption↗
PubMedDate not supplied

Surface modification of polycarbonate with synthetic polyelectrolyte-anticoagulant activity.

Natural rubber with C = C bonds had been modified by reaction with chlorosulfonyl isocyanate (CSI) and 70% of the products were obtained, which yielded polyelectrolyte on treatment with NaOH, having sulfamate and carboxylate groups. The polyelectrolyte showed anticoagulant activity. This might be due to the presence of both sulfamate and carboxylate groups arranged in a steric manner in the molecule as that of Heparin. Surface energy parameters, platelet adhesion and plasma recalcification time were investigated. Possible comparison with heparin had been demonstrated.

Anticoagulants↗