Showing papers by "Brunel University London published in 1987"
TL;DR: It is suggested that a component of protein glycosylation is dependent upon glucose autoxidation and subsequent covalent attachment of ketoaldehydes, and the chemical evidence for the currently accepted 'Amadori' product is consistent with the structure expected for the attachment of a glucose-derived ketoaldehyde to protein.
Abstract: Monosaccharide autoxidation (a transition metal-catalysed process that generates H2O2 and ketoaldehydes) appears to contribute to protein modification by glucose in vitro The metal-chelating agent diethylenetriaminepenta-acetic acid (DETAPAC), which inhibits glucose autoxidation, also reduces the covalent attachment of glucose to bovine serum albumin A maximal 45% inhibition of covalent attachment was observed, but this varied with glucose and DETAPAC concentrations in a complex fashion, suggesting at least two modes of attachment The extent of inhibition of the metal-catalysed pathway correlated with the extent of inhibition of glycosylation-associated chromo- and fluorophore development DETAPAC also inhibited tryptophan fluorescence quenching associated with glycosylation Conversely, ketoaldehydes analogous to those produced by glucose autoxidation, but generated by 60Co irradiation, bound avidly to albumin and accelerated browning reactions It is therefore suggested that a component of protein glycosylation is dependent upon glucose autoxidation and subsequent covalent attachment of ketoaldehydes The process of glucose autoxidation, or ketoaldehydes derived therefrom, appear to be important in chromophoric and fluorophoric alterations It is noted, consistent with these observations, that the chemical evidence for the currently accepted ‘Amadori’ product derived from the reaction of glucose with protein amino groups is consistent also with the structure expected for the attachment of a glucose-derived ketoaldehyde to protein The concept of ‘autoxidative glycosylation’ is briefly discussed in relation to oxidative stress in diabetes mellitus
1,294 citations
TL;DR: A 4-point interpolatory subdivision scheme with a tension parameter is analysed and it is shown that for a certain range of the tension parameter the resulting curve is C^1.
651 citations
TL;DR: How managers in ten companies view manufacturing flexibility in terms of how they see the contribution of manufacturing flexibility to overall company performance; what types of flexibility they regard as important; and what their desired degree of flexibility is is investigated.
Abstract: Many of the new pressures from today's manufacturing environment are turning manufacturing managers' attention to the virtues of developing a flexible manufacturing function Flexibility, however, has different meanings for different managers and several perfectly legitimate alternative paths exist towards flexible manufacturing How managers in ten companies view manufacturing flexibility in terms of how they see the contribution of manufacturing flexibility to overall company performance; what types of flexibility they regard as important; and what their desired degree of flexibility is The results of the investigations in these ten companies are summarised in the form of ten empirical “observations” Based on these “observations” a check‐list of prescriptions is presented and a hierarchical framework developed into which the various issues raised by the “observations” can be incorporated
626 citations
TL;DR: Chronic confinement for 1 month caused a significant elevation of plasma cortisol but suppressed the levels of plasma testosterone and 11-ketotestosterone in sexually mature male brown trout, and an acute handling stress for 1 hr elevated blood cortisol and ACTH levels and also suppressed circulating androgens.
250 citations
216 citations
01 Feb 1987
TL;DR: A broad-ranging account of free-radical biochemistry in general and offree-radical mechanisms of tissue injury in particular, and of the mechanisms that result in the production of free radicals.
Abstract: The present paper is a broad-ranging account of free-radical biochemistry in general, and of free-radical mechanisms of tissue injury in particular. Because it is broad-ranging within tight constraints of length it is necessarily lacking in detail on some issues of relevance; the following reviews can be consulted for additional coverage: Slater (1972, 1978, I&), Pryor (1976-84), Mason (1982), Halliwell & Gutteridge (1984). Free radicals can be defined as molecules or molecular fragments containing a single unpaired electron; this unpaired electron usually gives a considerable degree of chemical reactivity to the free radical: in chemical formulas the unpaired electron is conventionally shown as a ‘superscript dot’, as with the hydroxyl free radical OH’. Free radicals can be produced in the cells and tissues of our bodies by various processes and reactions; Table I divides these into two main sections: (I) formation of free radicals as a result of the impact of radiation, and (2) formation by reduction4xidation (redox) reactions involving the transfer of an electron. For discussion of the mechanisms that result in the production of free radicals, see Pryor (1966) and Slater (1972). Table I also indicates major ways by which free-radical intermediates can be converted to non-radical products by the action of free-radical scavengers; discussion of this important aspect of free-radical biochemistry is at the end of this paper. As already mentioned, free radicals are usually reactive chemically although some important examples of stable free radicals are known, such as diphenylpicrylhydrazyl (DPPH’) and Fremy’s salt (potassium nitrosodidphonate). The
163 citations
TL;DR: In this paper, the Dubinin-Radushkevich (DR) method has been used to determine nitrogen isotherms at 77 K on a number of carbon blacks and microporous carbons.
158 citations
TL;DR: In neutral solutions, desferrioxamine (Desferal) can react with the superoxide free radical, O2.- (possibly through its protonated form HO2.), to form a relatively stable nitroxide freeradical, which can have a half-life of approx.
Abstract: In neutral solutions, desferrioxamine (Desferal) can react with the superoxide free radical, O2.- (possibly through its protonated form HO2.), to form a relatively stable nitroxide free radical, which can have a half-life of approx. 10 min at room temperature. The formation of the radical can be largely prevented by the presence of superoxide dismutase. The radical reacts rapidly with cysteine, methionine, glutathione, vitamin C and a water-soluble derivative of vitamin E. It also reacts rapidly with alcohol dehydrogenase, causing a loss of enzyme activity. The implications of these findings for mechanistic free-radical biochemistry and iron-chelation therapy could be considerable.
134 citations
TL;DR: The problems of benefit measurement in the economic evaluation of heart transplant programmes are explored and the extent to which pre-transplant NHP scores can be used as predictors of post-trans transplant survival is examined.
123 citations
TL;DR: In this article, the proceedings of a two-week-long institute with learned contributors from many parts of the world have been published and the authors have discussed models and methods taken from a number of different disciplines.
106 citations
TL;DR: Cross-breeding experiments have proved that both R. sulcatus and R. turanicus are distinct taxonomic entities, and the morphological similarities between African and Cypriot strains of R.Turanicus demonstrated marked heterosis.
Abstract: For many years the biosystematic status of several species in the Rhipicephalus sanguineus group has been confused, with the result that they have often been misidentified. Over the years some 18 of these species have been synonymised with R. sanguineus (Latreille, 1806) itself. More recently four new species in the group have been described: R. guilhoni Morel & Vassiliades, 1963; R. moucheti Morel, 1964; R. bergeoni Morel & Balis, 1976; and R. camicasi Morel, Mouchet & Rodhain, 1976.
TL;DR: Current morphological and ecological data suggest that the inclusion of this species in the R. sanguineus group is questionable, and the larva, nymph, male and female of these two last named species are described with the aid of scanning electron micrographs (SEMs).
Abstract: In this, our second study on the biosystematics of the Rhipicephalus sanguineus group, we consider an additional five species found in the Afrotropical region, namely R. sanguineus, R. camicasi, R. guilhoni, R. moucheti and R. bergeoni.
TL;DR: In this article, the effects of a vertical baffle on the resonant frequencies of fluid within a rectangular container were investigated using the linearized theory of water waves, and the accuracy of simple approximate solutions was assessed by comparison with an accurate solution based on eigenfunction expansions.
Abstract: The effects of a vertical baffle on the resonant frequencies of fluid within a rectangular container are investigated using the linearized theory of water waves. The accuracy of simple approximate solutions is assessed by comparison with an accurate solution based on eigenfunction expansions. It is found that a surface-piercing barrier can change the resonant frequencies significantly while the effect of a bottom-mounted barrier is usually negligible.
TL;DR: The value of dexamethasone as a tool for investigating the role of interrenal tissue during stress responses in teleost fish is limited by its cortisol-like effects on other steroid-sensitive tissues.
TL;DR: Reaction of polyunsaturated fatty acid hydroperoxides with both Fe2+ and lipoxygenase under anaerobic conditions gives rise to signals not only from the alkoxy-radical adduct, but also from a further species which is tentatively identified as being due to an acyl [RC(O).]- radical adduct.
Abstract: The breakdown of cumene hydroperoxide and peroxidized fatty acids by iron is shown, by use of the spin trap 5,5-dimethyl-l-pyrroline-N-oxide, to be sensitive to (a) the oxidation state of the metal and (b) the nature of the chelating ligands. The initial step in the Fe2+-catalysed breakdown is the production of an alkoxyl radical by one-electron reduction, and this type of radical has been successfully trapped from each substrate. Subsequent reactions of this alkoxyl species produce both carbon-centred and peroxyl radicals, depending on the concentrations of the reagents present. The use of the same spin trap in microsomal systems undergoing either NADPH-supported or Fe2+-induced peroxidation led to the detection of low concentrations of radical adducts, among which are signals that are believed to be due to lipid alkoxyl radicals. Reaction of polyunsaturated fatty acid hydroperoxides with both Fe2+ and lipoxygenase under anaerobic conditions gives rise to signals not only from the alkoxy-radical adduct, but also from a further species which is tentatively identified as being due to an acyl [RC(O).]-radical adduct; chemical studies lend support to this assignment.
TL;DR: The tetramethylated spin trap TMPO though giving slightly less intense electron spin resonance (ESR) spectra, produces longer lived adducts, and is suggested to be of greater utility due to the more characteristic nature of the coupling constants of the observedAdducts.
TL;DR: In this article, a test method suitable for the routine assessment of fiber-matrix bond strength of thermoplastic composites was developed, which is sensitive enough to detect changes in interfacial bond strength resulting from different levels of silane applied to the glass fibre and the formation of transcrystalline morphology around the fibres.
TL;DR: In this article, cut-off functions are used to prove similar superconvergence results over interior subdomains, which allows superconcverage estimates to be derived for problems with solutions of low global regularity, particularly those involving singularities.
Abstract: Engineers have been aware for some time of the phenomenon of superconvergence, whereby there exist (stress) points at which the accuracy of a finite-element solution is superior to that of the approximation generally. This phenomenon has been treated in recent years by mathematicians who have proved, for certain two-dimensional secondorder elliptic problems, superconvergent error estimates for retrieved finite-element derivatives. These results have demanded high global regularity of the solutions of the bondary value problems. In this present article cut-off functions are used to prove similar superconvergence results over interior subdomains. This allows superconvergence estimates to be derived for problems with solutions of low global regularity, particularly those involving singularities.
TL;DR: The values obtained for the O2 addition to the thiyl radicals from glutathione and cysteine are considerable lower than those previously published, indicating that the RS.
Abstract: SummaryAbsolute rate constants for the addition of oxygen to thiyl radicals, i.e. RS + O2 → RSOO·, have been determined by applying a new competition method based on RS· formation via one-electron reduction of the corresponding disulphides, and the competition between RS· reacting with O2 and an electron donor such as ascorbate. Bimolecular rate constants have been obtained for the thiyl radicals derived from cysteine (6·1 × 107 mol−1 dm3 s−1), penicillamine (2·5 × 107 mol−1 dm3 s−1), homocysteine (8·0 × 107 mol−1 dm3 s−1), cysteamine (2·8 × 107 mol−1 dm3 s−1), 3-thiopropionic acid (2·2 × 108 mol−1 dm3 s−1) and glutathione (3·0 × 107 mol−1 dm3 s−1), respectively. The values obtained for the O2 addition to the thiyl radicals from glutathione and cysteine are considerable lower (by about two orders of magnitude) than those previously published. This indicates that the RS· + O2 reaction may be of complex nature and is generally a process which is not solely controlled by the diffusion of the reactants.
TL;DR: A novel functional role for gradients in the spatial sampling of the visual field, in relation to the internal representation of the structure and geometry of visible surfaces, is suggested.
Abstract: Contrast sensitivity was measured as a function of spatial frequency at various eccentricities in the nasal visual field. Eccentricity influenced resolution more for vertical gratings than for horizontal ones, demonstrating a nasal field anisotropy. When grating apertures and spatial frequencies were varied together, by changing viewing distance, peripheral and central contrast-sensitivity functions could not be entirely superimposed by scaling the spatial-frequency stimulus parameter. However, when gratings apertures were designed to project a standard-sized patch on a hypothetical vertical surface at an angle of 9 deg to the line of sight, the superimposition of central and peripheral contrast-sensitivity functions improved. Central and peripheral contrast-sensitivity functions can be superimposed by describing the grating stimulus with reference to this putative surface in terms of cycles per surface distance. The surface-scaling approach leaves a minor effect of eccentricity on contrast sensitivity for vertical gratings but readily accommodates the vertical-horizontal anisotropy in grating resolution. These findings suggest a novel functional role for gradients in the spatial sampling of the visual field, in relation to the internal representation of the structure and geometry of visible surfaces.
TL;DR: In this paper, five ceramic injection molding formulations with 65vol% powder and polypropylene as the main organic component were injection-moulded under identical conditions and the extent of mould filling and the production of molding defects in thick sections were examined in the light of rheological and shrinkage properties of the formulations.
Abstract: Five ceramic injection moulding formulations with 65vol% powder and polypropylene as the main organic component were injection -moulded under identical conditions. The extent of mould filling and the production of moulding defects in thick sections were examined in the light of rheological and shrinkage properties of the formulations.
TL;DR: In this article, the vanadate groups in the monolayer of VOx/TiO2 catalysts are used to accelerate pronene and acetone degradations.
TL;DR: In this paper, the authors examined the mechanical properties of the transcrystalline layer of a thermoplastics composites without fully characterizing the properties of such anisotropic layers.
Abstract: When a fibre is embedded into a thermoplastic melt it may act as a nucleant for the growth of spherulites. If there are many nucleation sites along a fibre's surface, then the resulting spherulite growth will be restricted in the lateral direction, so that a columnar layer, known as transcrystallinity [1] will develop and enclose the fibre. The presence of anisotropic layers, such as transcrystallinity, has significant implications for the performance of fibre-filled thermoplastics composites. Several workers [2-5] have examined this topic in composites, without fully characterizing the mechanical properties of the transcrystalline layer. As it is very difficult to establish the properties of such layers
TL;DR: It is proposed that limited free radical attack upon proteins, occurring continuously in cells, creates new N‐termini which render the proteins more susceptible to proteolysis by the ubiquitin conjugation system.
TL;DR: It is suggested that membrane-bound proteins are damaged during lipid peroxidation and that alpha-tocopherol protects cells against both types of damage.
Journal Article•
TL;DR: In this article, two heterocyclic thiosemicarbazones were synthesized and characterized by magnetic-moment measurement, and ESR and IR spectroscopy.
TL;DR: A distributed associative memory system which is ideal for scene analysis is described and shown to store associations between patterns more efficiently than a conventional file store.