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Biomedical subjects

J M Gutteridge

Publications and source records attributed to J M Gutteridge.

At least 109 records · Page 6Linked to original sources
PubMed1988

Bleomycin-detectable iron and phenanthroline-detectable copper in the cerebrospinal fluid of patients with neuronal ceroid-lipofuscinoses.

The neuronal ceroid-lipofuscinoses (NCLs) are a group of recessively inherited neurodegenerative lysosomal storage diseases, the pathogenesis of which is unknown. In the present study, we have measured iron and cooper in cerebrospinal fluids (CSF) using methods that detect these metals in a "loosely bound" form, complexable to the chelators bleomycin and 1,10-phenanthroline. We studied 25 children with NCL, 21 children with encephalopathy of some other type, and 5 control children without neurological complications. The CSF concentrations of loosely bound iron at neutral pH values and of loosely bound copper did not correlate with the clinical diagnosis of the patients, nor did they parallel degenerative symptoms in NCL, such as mental impairment, visual loss, motor handicap, and epilepsy. However, the concentrations of loosely bound iron and copper increased significantly with the age of the patient; this is a novel finding and may represent increasing tissue destruction with age. Our present findings do not support a major role for primary iron toxicity in the development of neuronal degeneration. To investigate any secondary pathological role for malplaced transition metals, further research is required.

Biomarkers↗
PubMed1988

Hydroxyl radical generation by the tetracycline antibiotics with free radical damage to DNA, lipids and carbohydrate in the presence of iron and copper salts.

Tetracycline antibiotics caused the degradation of carbohydrate in the presence of a ferric salt at pH 7.4. This degradation appeared to involve hydroxyl radicals since the damage was substantially reduced by the presence of catalase, superoxide dismutase, scavengers of the hydroxyl radical and metal chelators. Similarly, the tetracycline antibiotics in the presence of a ferric salt greatly stimulated the peroxidation of liposomal membranes. This damage, which did not implicate the hydroxyl radical, was significantly reduced by the addition of chain-breaking antioxidants and metal chelators. Only copper salts in the presence of tetracycline antibiotics, however, caused substantial damage to linear duplex DNA. Studies with inhibitors suggested that damage to DNA did involve hydroxyl radicals.

Animals↗
PubMed1988

Oxidative damage to DNA and deoxyribose by beta-lactam antibiotics in the presence of iron and copper salts.

beta-lactam antibiotics in the presence of certain metal ions damage deoxyribose and DNA with the release of thiobarbituric acid-reactive material. This damage can be substantially prevented by catalase, metal chelators and some scavengers of the hydroxyl radical. Ferric salts in the presence of certain beta-lactam antibiotics were effective in degrading deoxyribose but they did not appear to damage DNA. In contrast copper salts and beta-lactam antibiotics were extremely effective in damaging both DNA and deoxyribose.

Anti-Bacterial Agents↗
PubMed1987

Oxygen radical damage to DNA by rifamycin SV and copper ions.

The hydroquinone moiety of the antibiotic rifamycin SV reacts with molecular oxygen to form reduced oxygen intermediates such as superoxide (O2-.) and hydrogen peroxide (H2O2). The antibiotic semiquinone is also formed. Rifamycin SV in the presence of iron and copper salts can lead to the formation of the highly reactive hydroxyl radical (OH) which degrades the sugar deoxyribose. This damage is substantially inhibited by the enzyme catalase and scavengers of the hydroxyl radical such as formate, mannitol and thiourea. When linear duplex DNA is substituted for deoxyribose only rifamycin SV and copper ions substantially degrade DNA with release from the DNA molecule of thiobarbituric acid-reactive products. Damage to DNA by rifamycin and copper ions is significantly inhibited by catalase but poorly inhibited by scavengers of the hydroxyl radical consistent with a site-specific radical reaction of the DNA molecule. Several biological properties of rifamycin SV are known to resemble those of the metal chelating agent 1,10-phenanthroline. Here, we show that similarities extend to an unusual chemical property whereby thiobarbituric acid-reactive material is released from DNA in the presence of a copper salt.

Copper↗
PubMed1987

The deoxyribose method: a simple "test-tube" assay for determination of rate constants for reactions of hydroxyl radicals.

Hydroxyl radicals, generated by reaction of an iron-EDTA complex with H2O2 in the presence of ascorbic acid, attack deoxyribose to form products that, upon heating with thiobarbituric acid at low pH, yield a pink chromogen. Added hydroxyl radical "scavengers" compete with deoxyribose for the hydroxyl radicals produced and diminish chromogen formation. A rate constant for reaction of the scavenger with hydroxyl radical can be deduced from the inhibition of color formation. For a wide range of compounds, rate constants obtained in this way are similar to those determined by pulse radiolysis. It is suggested that the deoxyribose assay is a simple and cheap alternative to pulse radiolysis for determination of rate constants for reaction of most biological molecules with hydroxyl radicals. Rate constants for reactions of ATP, ADP, and Good's buffers with hydroxyl radicals have been determined by this method.

Ascorbic Acid↗
PubMed1987

Raised cerebrospinal-fluid copper concentration in Parkinson's disease.

The cerebrospinal-fluid copper concentration, measured by electrothermal atomisation/atomic absorption spectrophotometry, was significantly higher in 24 patients with untreated, idiopathic Parkinson's disease than in a control population of 34 patients (p less than 0.001). The difference in the in-vitro capacity of copper to damage DNA, measured by the phenanthroline assay was even greater. The high phenanthroline-copper concentration correlated with disease severity (p = 0.02) and with the rate of progression of disease (p less than 0.05). A possible role is suggested for copper-catalysed oxidative mechanisms in the pathogenesis of Parkinson's disease.

Adult↗
PubMed1987

Bleomycin-detectable iron in knee-joint synovial fluid from arthritic patients and its relationship to the extracellular antioxidant activities of caeruloplasmin, transferrin and lactoferrin.

Some 40% of knee-joint synovial fluids from arthritic patients show the presence of bleomycin-detectable iron. This is released from a protein component of the fluid to bleomycin at acidic pH values. Patients whose fluids release iron have lower contents of transferrin, lactoferrin and caeruloplasmin than do patients whose fluids do not release iron to bleomycin. These proteins are important extracellular antioxidants, and measured antioxidant activities are extremely low in the iron-releasing fluids. The propensity of some fluids to release iron at low pH values, characteristic of the microenvironment beneath adherent macrophages, coupled with their decreased antioxidant protection against iron-stimulated oxygen-radical damage, might explain previously reported correlations between clinical disease severity, lipid peroxide content and the presence of bleomycin-detectable iron [Rowley, Gutteridge, Blake, Farr & Halliwell (1984) Clin. Sci. 66, 691-695].

2,2'-Dipyridyl↗
PubMed1987

Ferrous-salt-promoted damage to deoxyribose and benzoate. The increased effectiveness of hydroxyl-radical scavengers in the presence of EDTA.

Hydroxyl radicals (OH.) in free solution react with scavengers at rates predictable from their known second-order rate constants. However, when OH. radicals are produced in biological systems by metal-ion-dependent Fenton-type reactions scavengers do not always appear to conform to these established rate constants. The detector molecules deoxyribose and benzoate were used to study damage by OH. involving a hydrogen-abstraction reaction and an aromatic hydroxylation. In the presence of EDTA the rate constant for the reaction of scavengers with OH. was generally higher than in the absence of EDTA. This radiomimetic effect of EDTA can be explained by the removal of iron from the detector molecule, where it brings about a site-specific reaction, by EDTA allowing more OH. radicals to escape into free solution to react with added scavengers. The deoxyribose assay, although chemically complex, in the presence of EDTA appears to give a simple and cheap method of obtaining rate constants for OH. reactions that compare well with those obtained by using pulse radiolysis.

Benzoates↗
PubMed1987

A method for removal of trace iron contamination from biological buffers.

Laboratory chemicals and reagents normally contain trace amounts of iron salts sufficient to catalyse free radical reactions. This iron contamination can be removed from buffers and reagents using a dialysis sac containing a high-affinity iron-binding protein like conalbumin or transferrin without altering the pH value of the fluid.

Bleomycin↗
PubMed1987

Allopurinol and oxypurinol are hydroxyl radical scavengers.

Allopurinol is a scavenger of the highly reactive hydroxyl radical (k2 approx. 10(9) M-1 X s-1). One product of attack of hydroxyl radical upon allopurinol is oxypurinol, which is a major metabolite of allopurinol. Oxypurinol is a better hydroxyl radical scavenger than is allopurinol (k2 approx. 4 X 10(9) M-1 X s-1) and it also reacts with the myeloperoxidase-derived oxidant hypochlorous acid. Hence the protective actions of allopurinol against reperfusion damage after hypoxia need not be entirely due to xanthine oxidase inhibition.

Allopurinol↗
PubMed1987

The antioxidant activity of haptoglobin towards haemoglobin-stimulated lipid peroxidation.

Haemoglobin stimulates the peroxidation of lipids in two discernable phases. The first phase is inhibited by binding haemoglobin to the protein haptoglobin. The second phase is stimulated by complexable iron released from the haemoglobin molecule during the process of lipid peroxidation. This latter peroxidation is inhibitable by transferrin and the iron chelator desferrioxamine. Heat-denatured haemoglobin and haemin both stimulated lipid peroxidation but this is not inhibitable by haptoglobin. It is suggested that the haptoglobins play an important antioxidant role in vivo by preventing iron-stimulated formation of oxygen radicals.

Antioxidants↗
PubMed1987

Mechanism of exacerbation of rheumatoid synovitis by total-dose iron-dextran infusion: in-vivo demonstration of iron-promoted oxidant stress.

The mechanism by which a synovial flare occurred in a patient with rheumatoid arthritis after intravenous infusion of iron-dextran was investigated. After the infusion, serum and synovial-fluid iron-binding capacity became saturated, giving rise to low-molecular-mass iron chelates with the capacity to cause oxidative damage ("bleomycin-iron"). At the same time lipid peroxidation and the concentration of oxidised ascorbic acid (dehydroascorbate) increased in both serum and synovial fluid, and red-cell glutathione fell. These changes corresponded closely to an exacerbation of rheumatoid synovitis. Hepatic function was transiently disturbed 7 days after the infusion, reflecting hepatic oxidant stress within the iron-loaded liver. Such changes provide clear evidence that iron-catalysed oxidative reactions influence the inflammatory process in human beings.

Arthritis, Rheumatoid↗
PubMed1986

Iron promoters of the Fenton reaction and lipid peroxidation can be released from haemoglobin by peroxides.

Hydrogen peroxide and organic hydroperoxides react with haemoglobin to release iron which can be complexed to apotransferrin, bleomycin and desferrioxamine. This released iron promotes deoxyribose degradation by a Fenton reaction, DNA degradation in the presence of bleomycin and stimulates lipid peroxidation. It is likely that iron released from haemoglobin is the true generator of hydroxyl radicals in the Fenton reaction.

Apoproteins↗