Biomedical subjects
P Cann
Publications and source records attributed to P Cann.
British Society of Gastroenterology guidelines for the management of the irritable bowel syndrome.
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The folding of an enzyme. II. Substructure of barnase and the contribution of different interactions to protein stability.
Barnase is described anatomically in terms of its substructures and their mode of packing. The surface area of hydrophobic residues buried on formation and packing of the structural elements has been calculated. Changes in stability have been measured for 64 mutations, 41 constructed in this study, strategically located over the protein. The purpose is to provide: (1) information on the magnitudes of changes in stabilization energy for mutations of residues that are important in maintaining the structure; and (2) probes for the folding pathway to be used in subsequent studies. The majority of mutations delete functional moieties of side-chains or make isosteric changes. The energetics of the interactions are variable and context-dependent. The following general conclusions may be drawn, however, from this study about the classes of interactions that stabilize the protein. (1) Truncation of buried hydrophobic side-chains has, in general, the greatest effect on stability. For fully buried residues, this averages at 1.5 kcal mol-1 per methylene group with a standard deviation of +/- 0.6 kcal mol-1. Truncation of partly exposed leucine, isoleucine or valine residues that are in the range of 50 to 80 A2 of solvent-accessible area (30 to 50% of the total solvent-accessible area on a Gly-X-Gly tripeptide, i.e. those packed against the surface) has a smaller, but relatively constant effect on stability, at 0.81 kcal mol-1 per methylene group with a statistical standard deviation of +/- 0.18 kcal mol-1. (2) There is a very poor correlation between hydrophobic surface area buried and the free energy change for an extensive data set of hydrophobic mutants. The best correlation is found to be between the free energy change and the number of methylene groups within a 6 A radius of the hydrophobic groups deleted. (3) Burial of the hydroxyl group of threonine in a pocket that is intended for a gamma-methyl group of valine costs 2.5 kcal mol-1, in the range expected for the loss of two hydrogen bonds.(ABSTRACT TRUNCATED AT 400 WORDS)
Long-term effects of elemental and exclusion diets for Crohn's disease.
Previous studies have confirmed the therapeutic value of elemental diets in promoting remission in active Crohn's disease, but their long-term benefit has not been established. Twenty-seven patients with established Crohn's disease who attained clinical remission after four weeks of enteral feeding were followed prospectively for up to 36 months. Twenty of these were willing to be tested for specific food intolerance using a pre-defined dietary elimination protocol; the others continued on a normal unrestricted diet. Eighteen patients (67%) have since relapsed; 89% of the relapse occurred within the first 6 months. Of the 15 patients with colonic involvement, 12 (80%) relapsed by 6 months. In contrast only 3 of 11 with isolated small bowel disease experienced early relapse. Of the 14 patients who completed the process of dietary testing, 5 could not identify any trigger foods; the remaining 9 were maintained on exclusion diets, 3 of whom relapsed early. Of the 11 taking a normal diet, 9 relapsed. Disease duration, previous intestinal resection or prior steroid therapy did not affect the relapse rate. Eight patients (31%) obtained a long-term remission, mean 23 months (range 12-36 months), without any medication. Long-lasting remissions can be obtained in about one-third of patients with Crohn's disease following treatment with a defined formula diet. Colonic involvement is associated with a high early relapse rate.
Timely intervention.
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Gerontological nurse specialists.
This article focuses on the development of a new role highlighted in The NHS Plan (DoH 2000a), nurse specialist for older people or gerontological nurse specialist.