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S P Wolff

Publications and source records attributed to S P Wolff.

At least 19 recordsLinked to original sources
PubMed1992

Ferrous ion oxidation in the presence of xylenol orange for detection of lipid hydroperoxide in low density lipoprotein.

A simple and sensitive method for the direct measurement of lipid peroxides in lipoprotein and liposomes is described. The method is based on the principle of the rapid peroxide-mediated oxidation of Fe2+ to Fe3+ under acidic conditions. The latter, in the presence of xylenol orange, forms a Fe(3+)-xylenol orange complex which can be measured spectrophotometrically at 560 nm. Calibration with standard peroxides, such as hydrogen peroxide, linoleic hydroperoxide, t-butyl hydroperoxide, and cumene hydroperoxide gives a mean apparent extinction coefficient of 4.52 x 10(4) M-1 cm-1 consistent with a chain length of approximately 3 for ferrous ion oxidation by hydroperoxides. Endoperoxides are less reactive or unreactive in the assay. The assay has been validated in the study of lipid peroxidation of low density lipoprotein and phosphatidyl choline liposomes. By pretreatment with enzymes known to metabolize peroxides, we have shown that the assay measures lipid hydroperoxides specifically. Other methods for measuring peroxidation, such as the assessment of conjugated diene, thiobarbituric acid reactive substances and an iodometric assay have been compared with the ferrous oxidation-xylenol orange assay.

Ferrous Compounds↗
PubMed1992

Trying times for human insulin.

The introduction of human insulin to treat diabetics seemed straightforward. What can account for the problems that have followed?

Animals↗
PubMed1992

Correlation between car ownership and leukaemia: is non-occupational exposure to benzene from petrol and motor vehicle exhaust a causative factor in leukaemia and lymphoma?

Although there is widespread agreement that many cancers have environmental causes we are often unable to see associations between specific cancers and exposure to environmental chemicals. One might also speculate that the more widespread, common-place and 'normal' a chemical exposure is perceived to be then the less likely it will be that the exposure is recognised, let alone be considered to cause cancer. Widespread contamination of air by chemicals associated with internal combustion may be an example of one such 'invisible' carcinogenic exposure. Yet evidence is available which suggests that many leukaemia and lymphoma cases, as well as other cancers, may be caused by this mundane and ubiquitous environmental contamination. The hypothesis is developed that leukaemia 'clustering' as well as national leukaemia incidence may be related to non-occupational exposure to benzene formed by petrol combustion and resulting from petrol evaporation. The possible association between exposure to fuel vapours, internal combustion products and cancer merits much closer examination than it receives at present.

Adolescent↗
PubMed1992

Formation of hydrogen peroxide by lens proteins: protein-derived hydrogen peroxide as a potential mechanism of oxidative insult to the lens.

The exposure of dialyzed preparations of lens crystallins to copper (II) ions causes a decrease in protein surface thiol and the production of hydrogen peroxide (H2O2). H2O2 production by gamma and beta crystallin subfractions (which contain the greatest level of thiol) is the predominant source of this H2O2. Protein surface thiols are probable sources of H2O2 formation since N-ethyl maleimide treatment of lens proteins and zinc ions inhibit H2O2 production. These data are consistent with a hypothesis that transition metal-catalyzed oxidation of protein contributes to cataractogenic lens protein oxidations.

Animals↗
PubMed1992

Hell on wheels.

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Automobiles↗
PubMed1992

Public health. Roads to poor health.

Simon P Wolff and Carola J Gillham highlight the negative health consequences of the motor car and argue that these are not inevitable. A land-use and transport policy which will protect and improve public health is not only possible but an urgent necessity.

Air Pollution↗
PubMed1991

Spirohydantoin inhibitors of aldose reductase inhibit iron- and copper-catalysed ascorbate oxidation in vitro.

Transition metal-catalysed oxidations have been implicated in the complications of diabetes. We report here that some experimental inhibitors of the enzyme aldose reductase (implicated in diabetes mellitus via its ability to catalyse glucose reduction to sorbitol) are also potent inhibitors of transition metal-catalysed ascorbate oxidation. The inhibition appears to be dependent upon the presence of a spirohydantoin group. It is conceivable that the copper- and iron-binding capacity of these compounds may contribute to some of their observed biological effects and may provide a starting point for a new generation of experimental drugs for the treatment of diabetes mellitus.

Aldehyde Reductase↗
PubMed1991

Bad taste.

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Animal Feed↗
PubMed1991

Health risks.

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Accidents, Traffic↗
PubMed1991

Lipid hydroperoxide measurement by oxidation of Fe2+ in the presence of xylenol orange. Comparison with the TBA assay and an iodometric method.

Study of the role of hydroperoxides and lipid peroxidation in disease requires simple and sensitive methods for direct hydroperoxide measurement. We report on a technique for measuring hydroperoxide which relies upon the rapid hydroperoxide-mediated oxidation of Fe2+ under acidic conditions. Fe3+ forms a chromophore with xylenol orange which absorbs strongly at 560 nm, yielding an apparent E560 (for H2O2, butyl hydroperoxide and cumene hydroperoxide) of 4.3 X 10(4) M-1 cm-1. The assay was validated in a study of liposomal lipid peroxidation and shown to give results comparable with those obtained by an iodometric method or by measuring conjugated dienes. The assay involving thiobarbituric acid, by comparison, underestimates lipid peroxidation and does not measure hydroperoxide per se.

Copper↗