Search PubMed⌕ Search

Biomedical subjects

D A Hall

Publications and source records attributed to D A Hall.

173 records · Page 10Linked to original sources
PubMed1966

The identification and estimation of elastase in serum and plasma.

1. Electrophoretic separation of partially purified elastase preparations from pancreas followed by incubation of the electrophoretogram in contact with an agar gel containing 4% of either Congo Red-stained or unstained elastin demonstrated that the enzyme which dissolves elastin can be identified with that which releases dye from the stained preparation. 2. A method for the estimation of elastase based on the release of dye from Congo Red-stained elastin is described. It is 23 times as sensitive as methods employing protein determination. 3. With the method, elastase activity can be identified in plasma and in a partially fractionated plasma protein preparation. 4. Lineweaver-Burk plots of these estimates of activity at a variety of substrate concentrations indicate that the reaction between elastase and the dyed elastin is more closely similar to that between elastase and the soluble substrate elastin rather than to that between elastase and the solid substrate. 5. Values for K(m) and V(max.) calculated for the enzyme present in plasma present further evidence for its identity with the pancreatic enzyme. 6. By calculation of the slopes of the Lineweaver-Burk plots for various enzyme concentrations it has proved possible to demonstrate that the inhibitor which is also present in the plasma is without effect on the enzyme when it acts on the dyed substrate.

Congo Red↗
PubMedDate not supplied

The chemistry of peroxovanadium compounds relevant to insulin mimesis.

The inorganic coordination chemistry of peroxovanadium compounds relevant to insulin mimesis is reviewed. The structure and kinetic reactivity of solutions of vanadate anion, vanadyl complexes and peroxovanadate complexes are briefly compared. Peroxovanadium compounds contain an oxo group, one or two peroxo ligands (O2(2-)) and an ancillary ligand which is usually bidentate. These compounds approximate a trigonal bipyramidal structure which can be divided conceptually into a polar 'oxo' half and a relatively non-polar organic half. This presents a number of interesting design variations which are discussed with respect to the development of a rudimentary structure-activity correlation of insulin mimetic ability.

Insulin↗
PubMedDate not supplied

Related age changes in the elastase and lipid contents of normal and hemiplegic subjects of various ages.

Elastase and lipid levels of the plasmas of subjects and of those who have suffered a stroke have been measured, and it has been shown that the normal age related fall in elastase content is mirrored more closely by the fall in high density lipoprotein cholesterol than by changes in total cholesterol. After a stroke a peak level of the elastase concentration is reached later than the peak of the total cholesterol, but before the peak for the HDL-cholesterol is attained. Highest levels of the ratio of these two (a major risk factor in vascular disease) appear to precede both the stroke and the elevation of the elastase level at ages below 76 whereas at higher ages than this the elevation of elastase precedes the lipid changes. It is therefore deduced that the whole question of elastolytic activity in the plasma is intimately bound up with the lipid content of the plasma and with the age of the subject as mirrored in the status of the elastic tissue in the vessel wall.

Age Factors↗
PubMedDate not supplied

The action of vitamin E on the ageing of connective tissues in the mouse.

In an attempt to determine the relevance of the free radical theory of ageing to age changes discernible in connective tissue parameters, a small colony of C3H/He and LAF1 mice was set up, with sample culled at intervals throughout the lifespan to provide experimental samples. To half of the stock a dietary supplement of vitamin E, a naturally occurring antioxidant, was given at a level of 2500 mg/kg of diet. Tests were carried out on culled samples to provide data on the total collagen levels of bone and skin, on thermal shrinkage temperature and maximal degree of shrinkage of tendon fibres, and on the recovery of skin from stress. Vitamin E was found to have no effect on any of the parameters measured on C3H/He mice but to exert an influence on the parameters of LAF1 mice around the age of 10 months. This influence, however, is not regarded as being relevant to the ageing of the tissues and thus no evidence can be derived for a free-radical mechanism playing a role in the ageing of connective tissues.

Aging↗