Publications

Apparent inactivation of α1-antiroteinase by sulphur-containing radicals derived from penicillamine

ALUMINOSILICATES AND ALZHEIMER'S DISEASE

Effect of overexpression of wild‐type or mutant parkin on the cellular response induced by toxic insults

Abstract Mutations in parkin are involved in some cases of autosomal recessive juvenile parkinsonism (AR‐JP), but it is not known how they result in nigral cell death. We examined the effect of parkin overexpression on the response of cells to various insults. Wild‐type and AR‐JP‐associated mutant parkins (Del3‐5, T240R, and Q311X) were overexpressed in NT‐2 and SK‐N‐MC cells. Overexpressed wild‐type parkin delayed cell death induced by serum withdrawal, H 2 O 2 , 1‐methyl‐4‐phenylpyridinium (MPP + ), or 4‐hydroxy‐2‐ trans ‐nonenal (HNE) but did not delay cell death caused by the proteasome inhibitor lactacystin. Increases in damage to proteins (protein carbonyls and 3‐nitrotyrosine) were attenuated by wild‐type parkin after serum withdrawal or exposure to H 2 O 2 , MPP + , or HNE but not after exposure to lactacystin. The mutant parkins (of all types) markedly accelerated cell death in response to all the insults, accompanied by increased levels of 8‐hydroxyguanine, protein carbonyls, lipid peroxidation, and 3‐nitrotyrosine and decreased levels of GSH. The viability loss induced by all the insults showed apoptotic features. The presence of parkin mutations in substantia nigra in Parkinson's disease may increase neuronal vulnerability to a range of toxic insults. © 2005 Wiley‐Liss, Inc.

Prostanoids: pharmacological, physiological and clinical relevance

Without doubt this book is unique amongst general texts on immunology.In their preface the authors tell us that they believe it to be "a remarkably unusual book".In the sense that it breaks new ground in the powerful visual appeal of its illustrations, it is.In other regards, however, it takes a well-tried and successful route in describing the subject.There are twenty-five chapters which take the reader from the general principles of adaptive and innate immunity through the cells and molecules of the immune system to the principles and features of immunity to infection,

Nontransferrin-bound iron in plasma from hemochromatosis patients: effect of phlebotomy therapy

Hydroxylation of salicylate by microsomal fractions and cytochrome <i>P</i>-450. Lack of production of 2,3-dihydroxybenzoate unless hydroxyl radical formation is permitted

Attack by hydroxyl radicals (.OH) upon salicylate (2-hydroxybenzoate) leads to formation of both 2,3-dihydroxybenzoate (2,3-DHB) and 2,5-dihydroxybenzoate (gentisate, 2,5-DHB). It has been suggested that formation of 2,3-DHB from salicylate is a means of monitoring .OH formation. Production of 2,3-DHB and 2,5-DHB by liver microsomal fractions and isoforms of cytochrome P-450 was investigated. Liver microsomes prepared from variously treated rats and rabbits catalysed the formation of 2,5-DHB but not 2,3-DHB. Formation of 2,5-DHB was inhibited by CO, metyrapone and SKF-525A, but not by the .OH scavengers mannitol and formate or by the iron chelator desferrioxamine. Purified P-450s IIE1, IIB4 or IA2 from rabbit liver microsomes, reconstituted together with NADPH-cytochrome P-450 reductase, led to formation of equal amounts of 2,3-DHB and 2,5-DHB in reactions that were almost completely inhibited by mannitol or formate. Addition of Fe3+/EDTA either to microsomes or to membranes containing reconstituted P-450 caused formation of approximately equal amounts of 2,3-DHB and 2,5-DHB, consistent with an .OH-dependent attack on salicylate. The data indicate that the microsomal P-450 system catalyses hydroxylation of salicylate to 2,5-DHB, but not formation of 2,3-DHB. Hence measurement of 2,3-DHB might provide a means of monitoring .OH formation. Care must be taken in studies of substrate hydroxylation by microsomes or reconstituted P-450 systems to avoid artefacts resulting from .OH generation.

?-phenylethyl isothiocyanate-mediated apoptosis in hepatoma HepG2 cells

Metal Ion Release from Mechanically-Disrupted Human Arterial Wall. Implications for the Development of Atherosclerosis

Oxidation of low density lipoproteins (LDL) in blood vessel walls plays a significant role in the development of atherosclerosis. LDL oxidation in vitro is greatly accelerated by the presence of "catalytic" iron or copper ions, which have already been shown to be present within advanced atherosclerotic lesions. We demonstrate here that mechanical damage to human arterial wall samples (both normal and early or intermediate atherosclerotic lesions) causes release of "catalytic" iron and copper ions, to an extent increasing with the damage. It may be that traumatic (e.g. during angioplasty) or other injury to the vessel wall contributes to the generation of metal ions that can facilitate LDL oxidation and other free radical reactions, so promoting atherosclerosis.

Measurement of oxidized and methylated DNA bases by HPLC with electrochemical detection

Oxidative DNA damage is thought to be an important contributor to cancer development and to be affected by dietary constituents, so its accurate measurement is important. DNA methylation is recognized as an important mechanism affecting gene expression. In the present paper we describe an HPLC-with-electrochemical-detection procedure that allows rapid and sensitive measurement of four oxidized (2,6-diamino-4-hydroxy-5-formamidopyrimidine, 5-hydroxyuracil, 8-hydroxyguanine, 8-hydroxyadenine) and three methylated (7-methylguanine, 1-methylguanine, O6-methylguanine) bases in acid hydrolysates of DNA. Guanine was also detected, but was clearly separated from the other bases.

The Liver, Biology and Pathobiology (Second Edition)

Plant Organelles

by R. R. Reid and R. M. Leech The Blackie Publishing Group; Glasgow, London

Superior Photoprotection of Cyanine Dyes with Thio-imidazole Amino Acids

Preventing fluorophore photobleaching and unwanted blinking is crucial for singlemolecule fluorescence studies. Reductants achieve photoprotection via quenching excited tripletstates, yet either require counteragents, or for popular alkyl-thiols, are limited to cyanine dye Cy3 protection. Here we provide mechanistic and imaging results showing that the naturally occurring amino acid ergothioneine and its analogue dramatically enhance photostability for Cy3, Cy5 and their conformationally restrained congeners, providing a biocompatible universal solution for demanding fluorescence imaging.

Reactive species can pose special problems needing special solutions: some examples

Abstract This chapter describes several situations in which free radicals/reactive species (RS) are especially problematic and require special protective mechanisms. The first is the gastrointestinal tract, which is exposed to pro-oxidants from the diet and must protect itself from oxidative damage using a range of antioxidants. It also produces some RS for useful purposes, including the regulation of bacterial colonization, by NADPH oxidase enzymes. The respiratory tract has to cope with inhaled air pollutants (O3, NO2, SO2, and O2 itself) and contains many antioxidants (especially GSH) in its lining fluids and cells. The relation of antioxidants (especially vitamin C) to asthma is also reviewed. Erythrocytes have special problems because of the haemoglobin they carry, which can oxidize to generate superoxide. Hence erythrocytes are rich in antioxidants. The effects of toxins (e.g. favism), glucose-6-phosphate dehydrogenase deficiency, and infection with malaria parasites on oxidative damage in erythrocytes are presented. Indeed, malaria can be treated with drugs that impose oxidative stress, such as artemisinin. Plants are discussed in detail, including the mechanisms of photosynthetic O2 production, how plants protect themselves against O2 toxicity (using many antioxidants, especially carotenoids), and how they can be damaged by poisons such as paraquat, air pollutants, atrazine, or oxyfluorfen. The problems of the ear and the involvement of RS in hearing loss are discussed. Conception (spermatozoa, ova), pregnancy, embryonic development, normal birth, and premature birth, and the action of teratogens are also considered in the free-radical/antioxidant context, as are the potential benefits and harm from exercise.

Free radicals in biology and medicine

No abstract is provided for this article.

SNFS Advances in Nutrition Lecture - Sponsored by SNFS

The mechanism of initiation of lipid peroxidation. Evidence against a requirement for an iron(II)-iron(III) complex

When Fe2+ ions are added to rat-liver microsomes, lipid peroxidation begins after a short lag period. Fe2+-dependent peroxidation in the first few minutes of the incubation can be increased by adding Fe3+, ascorbic acid or Pb2+ ions; these stimulations are not additive. By contrast, Pb2+ ions inhibit peroxidation of microsomes in the presence of Fe3+/ascorbate or Fe3+-ADP/NADPH. In liposomes made from ox-brain phospholipids, Fe2+-dependent peroxidation is stimulated slightly by Fe3+, but much more so by ascorbic acid, Al3+ or Pb2+; these stimulations are not additive. Liposomal peroxidation in the presence of Fe3+/ascorbate is inhibited by Pb2+ or Al3+. These results argue against the participation of an Fe2+-Fe3+-O2 complex, or a critical 1:1 ratio of Fe2+ to Fe3+, in the initiation of lipid peroxidation in liposomes and rat-liver microsomes.

The role of superoxide and hydroxyl radicals in the degradation of hyaluronic acid induced by metal ions and by ascorbic acid

Purified commercial hyaluronic acid contains significant amounts of iron. Addition of Fe2+ to solutions of it causes depolymerization, which is inhibited by catalase and scavengers of the hydroxyl radical (·OH) but not by superoxide dismutase. Fe3+ is ineffective. Ascorbic acid also depolymerizes hyaluronic acid, apparently because it can reduce Fe3+ in the reaction mixtures to Fe2+. Ascorbate-induced depolymerization is inhibited by the specific iron chelator desferrioxamine, by catalase, and by scavengers of the hydroxyl radical. The relevance of these observations to rheumatoid arthritis and inflammatory joint diseases is discussed.