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Biomedical subjects

J H Braybrook

Publications and source records attributed to J H Braybrook.

3 recordsLinked to original sources

The biocompatibility of glass-poly(alkenoate) (Glass-Ionomer) cements: a review.

The literature describing the biocompatibility of glass-poly(alkenoate) ('Glass-Ionomer') cements has been reviewed. This literature shows that these materials have generally good biocompatibility for both dental and orthopaedic use, this latter observation being very recent. There have, though, been a few reports showing that in certain circumstances these materials may cause pulpal irritation and the reasons for these particular findings are considered. Following discussion of the biocompatibility of Glass-Ionomer cements, consideration is given to the likely underlying causes of this feature. Three factors are identified as contributing to the biocompatibility of these cements. They are: (i) minimal exotherm on setting; (ii) rapid neutralization following mixing; and (iii) slow release of ions which are generally biologically beneficial or, at least, benign. This last point is considered in some detail. Previous studies of leaching of ions from Glass-Ionomer cements have shown that only inorganic species are released. The biological effects of each of these inorganic ions are described and their influence on biocompatibility discussed.

Aluminum

Polymeric controlled release systems.

There are wide applications of great importance for the improved and efficient administration of many materials--particularly in the pharmaceutical area. The introduction of novel polymeric materials and related formulation technologies now provide a versatile means for the precisely controlled delivery of many physiologically active substances. A further advantage is a decrease in patient discomfort and compliance, and decreased side-effects.

Chemistry, Pharmaceutical

Effect of pH on the nuclear magnetic resonance relaxivity of encapsulated solid paramagnetic substances.

Encapsulation, by acid-stable materials, of solid paramagnetic metal complexes based on sulphonated polystyrene ion-exchange resin, prevents the significant demetallation which otherwise occurs when the complexes are subjected to an acidic environment equivalent to that of the human stomach (pH 1-2). In turn, this protects the ability of those complexes to enhance the nuclear magnetic resonance (NMR) spin-lattice relaxation rate of water. Application of the results in the development of contrast agents for MR imaging of the gastrointestinal (GI) tract, in the evaluation of coatings used in drug formulations, and in the measurement of GI transit times of drugs is suggested.

Capsules