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Biomedical subjects

J M Gutteridge

Publications and source records attributed to J M Gutteridge.

At least 199 records · Page 11Linked to original sources
PubMed1979

Inhibition of the iron-catalysed formation of hydroxyl radicals from superoxide and of lipid peroxidation by desferrioxamine.

The peroxidation of membrane phospholipids induced in vitro by ascorbic acid or by dialuric acid (hydroxybarbituric acid) does not occur in the absence of traces of metal ions. Peroxidation induced by adding iron salts to phospholipids can either be promoted or inhibited by the chelators EDTA, diethylenetriaminepenta-acetic acid and bathophenanthrolinesulphonate, depending on the ratio [chelator]/[iron salt]. The iron chelator desferrioxamine inhibits peroxidation at all concentrations tested, and it also inhibits the iron-catalysed formation of hydroxyl radicals (OH.) from superoxide (O2-.). Since desferrioxamine is approved for clinical use, it might prove a valuable tool in the treatment of inflammation, poisoning by autoxidizable molecules and radiation damage.

Chelating Agents↗
PubMed1978

A simple colorimetric method for the estimation of plasma biliverdin.

A new colorimetric method for the assay of biliverdin in biological fluids is described. The method, based upon the reaction of biliverdin with barbituric acid, offers improved sensitivity and selectivity when compared to direct spectrophotometric measurements. Using this method biliverdinaemia was observed in two patients with obstructive jaundice of malignant origin.

Ascorbic Acid↗
PubMed1978

The characterisation of thiobarbituric acid reactivity in human plasma and urine.

The specificity of the thiobarbituric acid reaction (TBA) has been investigated using techniques of high-performance thin-layer chromatography and spectrofluorimetry. It was found that malondialdehyde (MDA) derived from different lipid and nonlipid origins formed the same MDA-TBA complex. This complex could be separated from other TBA-reactive compounds by both chromatography and spectrofluorimetry. Normal human plasma and urine both formed an MDA-TBA complex along with other TBA-reactive compounds. In plasma this was associated mainly with phosphatidylcholine and appeared to be peroxidic in reaction. Urine, however, contained polar MDA-forming compounds probably resulting from the oxidation of 2-deoxyaldoses during the acid-heating stage of the TBA test.

Chromatography, Thin Layer↗
PubMed1978

Caeruloplasmin: a plasma protein, enzyme, and antioxidant.

Multifunctional roles of the plasma protein, caeruloplasmin, have been briefly reviewed under three main headings. These are protein functions, enzymic activity, and antioxidant protection. As a plasma protein it is said to play a role in the transport of copper. Since some 95% of serum copper is associated with caeruloplasmin, measurement of the protein provides a useful guide to copper levels. Enzymic functions are related to its oxidase activity. Substrates commonly used for laboratory assay include non-biologically occurring aromatic amines and polyphenols. More recently, a physiological function has been proposed in which the enzyme oxidases iron from the ferrous to ferric state for binding to apotransferrin. This enzymic function of caeruloplasmin has been designated 'ferroxidase'. In vitro studies have shown that caeruloplasmin can inhibit the peroxidation of polyunsaturated fatty-acids. This function is in part related to its ferroxidase activity. No antioxidant activity has yet been demonstrated in vivo but this possibility is speculatively discussed.

Biogenic Amines↗
PubMed1978

The membrane effects of vitamin E, cholesterol and their acetates on peroxidative susceptibility.

Ox-brain phospholipid liposomes provide an organised membrane structure as well as a substrate for lipid peroxidation. Vitamin E is a poor antioxidant outside the membrane but has considerable activity within. Inclusion of its acetate derivative confirmed the dual role of vitamin E as both a stabilising structural component and free-radical scavenger. Cholesterol similarly stabilises the membrane but does not appear to significantly protect by radical scavenging. Its functions are closely related to the amount and type of phospholipid present in the membrane. Changes in oxidative susceptibility following free-radical stress provide a sensitive measure of membrane structural organisation.

Animals↗
PubMed1976

Superoxide dismutase (erythrocuprein) and free radicals in clinical chemistry.

Erythrocuprein (superoxide dismutase) has recently been shown to have an enzymic function towards superoxide anions. The discovery of superoxide dismutase, its mode of action, and estimation are reviewed along with a brief introduction to oxygen activation and free-radical chemistry. The formation, activity, and destruction of oxygen free radicals in white blood cells, red blood cells, and subcellular particles are discussed. (a) The production of superoxide anions by white cells during phagocytosis is thought to be advantageous for the overall bactericidal event. (b) Normal red blood cells generate low levels of superoxide anions. Increased levels of free-radical production could play a significant role in accelerating cell ageing (haemolysis). (c) Subcellular particles produce superoxide anions. These as well as organic peroxides have been implicated in drug hydroxylation reactions involving cytochrome P-450.

Cytochrome P-450 Enzyme System↗