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Biomedical subjects

K Ridgway

Publications and source records attributed to K Ridgway.

At least 19 recordsLinked to original sources

A procedure for the purification of ferritin from human liver by heating a methanol-treated homogenate.

A simple, rapid technique for purification of ferritin from human liver tissue is described. Methanol, at a final concentration of 40% (v/v) in liver homogenate, precipitates the majority of proteins but does not affect ferritin. Subsequent heating of this homogenate at 75 degrees C for 10 min results in a purified ferritin preparation as judged by immunoelectrophoresis and polyacrylamide gel electrophoresis. The resultant purified ferritin contained the same amount of iron as the original endogenous ferritin. There were no significant differences (paired t tests) in the amount of protein in the purified ferritin preparation when measured by rocket immunoelectrophoresis and by the Lowry procedure, suggesting that the antigenecity of ferritin was unaffected by the methanol and heat treatment. Both endogenous liver ferritin and radiolabeled human liver ferritin added to liver homogenates were recovered after methanol and heat treatment with similar yields (77 +/- 7% and 70 +/- 2%, respectively) when compared with the standard treatment of heating a homogenate at 75 degrees C. The overall ferritin yield with this rapid procedure was 40%.

Chromatography, High Pressure Liquid

An evaluation of the properties of enteric coating polymers: measurement of glass transition temperature.

When submitted to X-ray crystallography, two enteric coating polymers, cellulose acetate phthalate and polyvinyl acetate phthalate, were found to be essentially amorphous in structure. Values for the glass transition temperature, Tg, of each polymer have been obtained using both a surface microindentation technique and differential scanning calorimetry. The effect on this parameter of an increasing concentration of a plasticizer, diethyl phthalate, has also been determined. Measured values for Tg have been compared with predicted values obtained using a suitable mixture-rule model: the surface microindentation technique values were closer to the predicted.

Cellulose

The permeability of enteric coatings and the dissolution rates of coated tablets.

The effect of an increasing concentration of plasticizer and pigment on the permeability to both water vapour and simulated gastric juice of cellulose acetate phthalate and polyvinyl acetate phthalate has been evaluated. There were significant differences between the permeability coefficients of each polymer, particularly with regard to water vapour. The presence of additives within the film coatings had a greater effect on the properties of cellulose acetate phthalate than those of polyvinyl acetate phthalate. Suitable formulations of each polymer were used to enteric coat 325 mg aspirin tablets, which were subsequently subjected to both the Disintegration Test for Enteric Coated Tablets B.P. and a dissolution procedure to monitor the release of drug in simulated gastric juice and simulated intestinal fluid. Both polymers demonstrated their suitability for producing enteric coatings. However, polyvinyl acetate phthalate yielded a faster release of aspirin in simulated intestinal fluid than did cellulose acetate phthalate.

Cellulose