Search PubMed⌕ Search

Biomedical subjects

D E Pratt

Publications and source records attributed to D E Pratt.

29 records · Page 2Linked to original sources
PubMed1975

Lipid analysis of a frozen egg substitute.

The lipid composition of an egg substitute and fresh eggs was conpared. The total lipid was divided into fractions on a silicic acid column. Thin-layer-chromatographic analysis demonstrated that the egg substitute was practically void of cholesteryl esters. Gas-liquid-chromatographic analysis were used to ascertain the fatty acid composition of the various fractions. Eggs contained considerably higher concentrations of saturated and mono-unsaturated fatty acids than did the substitute. The polyunsaturated fatty acid concentration in the substitute was approximately three times that of eggs. In all fractions, the eggs contained several more individual fatty acids than did the egg substitute.

Calcium, Dietary↗
PubMedDate not supplied

Inhibition of protein-tyrosine kinase activity by flavanoids and related compounds.

A series of 22 flavanoids and related compounds were tested for their ability to inhibit the activity of a protein-tyrosine kinase purified from bovine thymocytes (p40). Flavones or flavanols with hydroxyl groups at C-5 and C-7 or with three hydroxyl groups on the phenyl ring were potent inhibitors of p40. The replacement of hydroxyl groups with methoxyl groups led to a substantial loss of inhibitory activity. The presence of methoxyl or rhamnosyl substituents at C-3 also abolished inhibitory activity. Kinetic analyses indicated that the flavone apigenin [2] was a competitive inhibitor of p40 with respect to ATP. Flavanones and isoflavones were relatively inactive as protein-tyrosine kinase inhibitors. The isoflavone genistein [17], which has been reported as a potent inhibitor of both pp60(v=src) and the epidermal growth factor receptor, was not an inhibitor of p40.

Animals↗
PubMedDate not supplied

Sulphite stabilization and high-performance liquid chromatographic determination: a reference method for free and reversibly bound sulphite in food.

A high-performance liquid chromatographic (HPLC) post-column reactor combination has been developed for the determination of sulphite (free and reversibly bound) in 15 different foods. The foods were treated with a pH 5.1 buffered aqueous 2% formaldehyde solution to convert the labile sulphite to the relatively stable hydroxymethylsulphonate. Reverse-phase ion-pairing HPLC with a post-column detector consisting of an initial reaction with KOH followed by colorimetric reaction with Ellman's reagent buffered at pH 6.3 were used for separation and quantitation. The photometric detector at 412 nm quantitated the strongly absorbing 3-carboxy-4-nitrothiophenolate anion, the product of the sulphite reaction with Ellman's reagent. The recovery at levels of 5-100 ppm as sulphur dioxide was greater than 90% by reverse isotope dilution assay. Repetitive analysis of a single grape juice extract containing 20 ppm SO2 showed a relative standard deviation of 2.2%.

Chromatography, High Pressure Liquid↗