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D De Bono

Publications and source records attributed to D De Bono.

10 recordsLinked to original sources
PubMed1994

The effect of myoglobin on the stability of the hydroxyl-radical adducts of 5,5 dimethyl-1-pyrolline-N-oxide (DMPO), 3,3,5,5 tetramethyl-1-pyrolline-N-oxide (TMPO) and 1-alpha-phenyl-tert-butyl nitrone (PBN) in the presence of hydrogen peroxide.

The hydroxyl radical adducts of 5,5 dimethyl-1-pyrolline-N-oxide (DMPO) and 3,3,5,5 tetramethyl-1-pyrolline-N-oxide (TMPO) formed in the presence of hydrogen peroxide and FeII are normally quite stable, but in the presence of 5-20 micromolar myoglobin their ESR signals decay rapidly. This decay probably reflects further oxidation of the adduct to nonparamagnetic products. The ESR signal of the hydroxyl radical adduct of 1-alpha-phenyl-tert-butyl nitrone (PBN) formed under similar conditions is subject to non-heme dependent attenuation, possibly via hydroxyl radical scavenging, but not to heme dependent decay. Hydrogen peroxide readily converts myoglobin to its ferryl (FeIV) derivative, and this centre may be responsible for the oxidation of the DMPO and TMPO adducts. The different behaviour of PBN may be due to differences in susceptibility to ferrylmyoglobin mediated oxidation, or to steric differences controlling access to the heme pocket of myoglobin, and is relevant to the choice of spin trap for biological experiments aimed at detecting hydroxyl radicals in the presence of myoglobin or other heme proteins.

Cyclic N-Oxides↗
PubMed1993

The effects of myoglobin and apomyoglobin on the formation and stability of the hydroxyl radical adduct of 5,5'-dimethyl-1-pyrroline-N-oxide.

When aqueous solutions of the spin trap 5,5'-dimethyl-1-pyrroline-N-oxide (DMPO) are treated with hydrogen peroxide in the presence of either FeII or light, the hydroxyl radical adduct DMPO-OH is formed, with a characteristic 4 line ESR spectrum. When oxy- or metmyoglobin is added to such a system the initial yield and the halife of DMPO-OH are reduced, and at high myoglobin concentrations (about 0.1 mmol dm-3) DMPO-OH becomes undetectable. Using the stable nitroxide 2,2,6,6-tetramethyl-1-piperidinyloxy-N-oxyl (TMPO) for comparison it was found that neither hydrogen peroxide nor myoglobin alone caused a loss of signal, but together a marked loss of signal was induced. From the evidence of these and other experiments it was concluded that the DMPO-OH adduct reacts with hydrogen peroxide and myoglobin to give non-paramagnetic products, and hence that the use of the DMPO spin trap to detect hydroxyl or other active radicals in systems containing physiological concentrations of myoglobin may give misleading results.

Apoproteins↗
PubMed1975

En face organ culture of vascular endothelium.

A simple technique is described for maintaining in organ culture segments of blood vessel in such a way that the endothelium can be studied en face. The behaviour of such cultures throws further light on the interaction between endothelium and intravascular clotting.

Animals↗
PubMedDate not supplied

Mega-trials.

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Clinical Protocols↗