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Biomedical subjects

I Strachan

Publications and source records attributed to I Strachan.

9 recordsLinked to original sources

Medicines and older people: a nurses' guide to administration.

Older people represent only 18% of the population but receive approximately 45% of all prescribed medication in the UK (Offerhaus, 1997). Problems arising from drug therapy are numerous, as medication will often act in a number of complex and even surprising ways. As the number of older people grows, it becomes increasingly necessary for nurses to recognize and understand the legal and professional issues relating to the administration of medicines. This article outlines some of the potential problems confronting the nursing profession and offers some practical solutions to common dilemmas.

Aged↗

Distribution, purification and properties of 1-aspartamido-beta-N-acetylglucosamine amidohydrolase.

1. The activity of the enzyme that splits 2-acetamido-1-l-beta-aspartamido-1,2-dideoxy-beta-d- glucose (1-aspartamido-beta-N-acetylglucosamine) was measured in tissues from different mammalian species. 2. The enzyme from an aqueous extract of rat liver was purified 150-fold in 56% yield. 3. Optimum activity for the hydrolysis of 1-aspartamido-beta-N-acetylglucosamine was at pH7, and ammonia and N-acetylglucosamine were liberated in equimolar amounts. At pH8.5, 1-amino-N-acetylglucosamine was the only sugar produced after short periods of incubation. On prolonged incubation there was spontaneous liberation of ammonia from this compound. 4. It is concluded that the enzyme is an amidase.

Amidohydrolases↗

The enzymic degradation of ovalbumin and its glycopeptides.

1. Ovalbumin glycopeptides, freed from all amino acids other than aspartic acid and a small proportion of leucine by repeated digestion with Pronase, were hydrolysed by 1-aspartamido-beta-N-acetylglucosamine amidohydrolase (glycoaspartamidase) to the corresponding oligosaccharides. The glycoaspartamidase did not attack ovalbumin itself. 2. Ovalbumin, with mannose/hexosamine ratio 5:4, lost 1.5moles of N-acetylglucosamine and more than 2moles of mannose after incubation with alpha-mannosidase and beta-N-acetylglucosaminidase respectively. 3. In ovalbumin glycopeptides with approximate mannose/hexosamine ratios 5:3 and 5:4, one and two N-acetylglucosamine residues respectively were accessible to the action of beta-N-acetylglucosaminidase. 4. A mixture of alpha-mannosidase and beta-N-acetylglucosaminidase, acting on an ovalbumin glycopeptide with mannose/hexosamine ratio 5:3.7, removed nearly 4moles of mannose and 1.5moles of N-acetylglucosamine. 5. alpha-Mannosidase removed about 1.5moles of mannose from the ovalbumin oligosaccharide with mannose/hexosamine ratio approx. 5:3. The subsequent action of beta-N-acetylglucosaminidase liberated less than 1mole of N-acetylglucosamine and made at least 1mole further of mannose accessible to alpha-mannosidase action. 6. It is concluded that the carbohydrate moiety of ovalbumin is linked through a glycosyl group to asparagine. In a molecule with mannose/hexosamine ratio 5:4, there are two beta-N-acetylglucosamine residues linked together in a terminal position, followed by alpha-mannose. There is also present a side chain containing two alpha-mannose units.

Amidohydrolases↗

Inhibition of glycosidases by aldonolactones of corresponding configuration: Preparation of (1-->5)-lactones by catalytic oxidation of pyranoses and study of their inhibitory properties.

1. A method was devised for the preparation of (1-->5)-lactones from pyranose sugars and uronic acids by platinum-catalysed oxidation with gaseous oxygen in aqueous solution at acid pH. It was applied to mannose, N-acetylglucosamine, N-acetylgalactosamine, glucuronic acid, galacturonic acid, galactose, l-arabinose and d-fucose. 2. Only the first three yielded products that could be obtained in the solid state without decomposition. In every case, however, the oxidation product in aqueous solution behaved as the aldono-(1-->5)-lactone, and was more inhibitory towards the appropriate glycosidases than any aldonolactone preparation hitherto examined. 3. The stabilities of the oxidation products were studied, and their interconversion with the (1-->4)-lactones was demonstrated. Ring-opening does not appear to be mandatory for this isomeric change, which in some instances is very rapid. 4. To explain all the inhibitory effects observed with aldonolactones on glycosidases of corresponding configuration, it is tentatively postulated that inhibition may be due entirely to the (1-->5)-lactone, and that any inhibitory effect seen with the (1-->4)-lactone is a measure of the extent and speed of its conversion into the (1-->5)-lactone in aqueous solution.

Journal Article↗