摘要:

The reaction of streptozotocin with oxymyoglobin was analyzed and compared with results using various compounds that spontaneously generate nitric oxide in solution.

ISSN:1071-5762    

DOI:10.3109/10715769609088003

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Addition of H2O2at 100μM, or 1 mM, to the culture medium of BHK-21 fibroblasts results in increased intracellular levels of H2O2. Whilst exposure of BHK-21 cells to lower levels of H2O2(1μM) actually stimulates proliferation, these higher oxidant concentrations not only depress proliferation rates but also lead to an increase in the appearance of apoptotic-like cells in the cultures. Other agents such as inhibitors of glutathione peroxidase and catalase, or mimics of superoxide dismutase, which also bring about elevated cellular levels of H2O2in BHK-21 cells, similarly lead to decreased proliferation and an apparent increase in cells with apoptopic features. Thus intracellular conditions which are considered more prooxidant than normal, appear to favour apoptosis over proliferation in BHK-21 fibroblasts. Additionally these abnormal cellular conditions also appear to favour excessive DNA replication, in remaining non-apoptotic cells.

ISSN:1071-5762    

DOI:10.3109/10715769609088004

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

The antioxidant and pro-oxidant properties of L-DOPA and dopamine were investigatedin vitro. Both compounds inhibited the peroxidation of ox-brain phospholipids, with IC50values of 8.5μM for dopamine and 450μM for L-DOPA. Dopamine and L-DOPA reacted with trichloromethyl peroxyl radicals (CC13O2) with rate constants of 2.1×107M1s-1and 1.3×107M-1s-1respectively. The effects of dopamine and L-DOPA on iron ion- dependent hydroxyl radical generation from H2O2were c:mplex. In general, low concentrations stimulated OH formation in the presence of ferric-EDTA and, in the case of L-DOPA, ferric-ADP and ferric citrate chelates. Both compounds also reacted with superoxide radical and hypochlor-ous acid. The products of the reaction with HOCI could still inhibit al-antiproteinase and appear to be 'long lived' chloramine-type oxidizing species. Our results suggest that L-DOPA and dopamine might have a complex mixture of pro- and anti- oxidant effects, which could contribute to tissue damage due to oxidative stress in Parkinson's disease and other neurological disorders.

ISSN:1071-5762    

DOI:10.3109/10715769609088005

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

The effect of hyperlipemic human serum on superoxide anion (O2−) production by rat peritoneal macrophages was investigated. Phorbol myristate acetate (PMA)-stimulated O2−production was inhibited when cells were preincubated with hyperlipemic human serum. This inhibition was specifically carried out by a lipid fraction and was dependent on both cholesterol and triglyceride serum levels. This inhibitory effect was not exerted by a direct effect on NADPH-oxidase activity, nor by a putative superoxide dismutase activity present in the serum. With human neutrophils, we observed a decreased mobility of the cytosolic factor p47-phox to the membrane during the activation process, caused by hyperlipemic serum. We did not find any effect of hyperlipemic serum on NO2−production by cultured rat macrophages. These results suggest that a pathological increase of circulating plasma lipids may be associated with an impaired inflamatory capacity of macrophages.

ISSN:1071-5762    

DOI:10.3109/10715769609088006

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

An isolated rat heart model of intermittent hypoxia was used to investigate the impact of exogenous supplementation of glutathione and two thiol delivery vehicles on functional recovery during reoxygenation and whether efficacy was dependent on enhanced intracellular thiol concentration. Hearts from F344 rats were perfused in the Langendorff mode and exposed to three, 5 minute bouts of global, substrate free, normothermic hypoxia separated by 5 minute reoxygenation periods. Changes in coronary flow, heart rate, systolic and diastolic pressure, and rate pressure product were evaluated throughout in control hearts and compared with hearts in which one of the following was provided during the hypoxic periods: reduced glutathione (GSH, 1 or 10 mM), 10 mM GSH mono-ethyl ester (GSHMEE), or 1 mM L-2-oxothiozolidine-4-carboxylate (OZT). After three hypoxic periods plus reoxygenation, rate pressure product in control hearts was - 60% of pre-hypoxic values. Exposing hearts to 1 or 10 mM GSH, 10 mM GSHMEE, or 1 mM OZT significantly (p<0.05) enhanced post-hypoxic recovery of rate pressure product and attenuated the rise in diastolic pressure during hypoxia. This improvement in function was not associated with an elevated intracellular thiol concentration in treated hearts. Cumulative oxidative changes may occur during intermittent hypoxia via a mechanism localized on or near the sarcolemmal membrane. These changes appear to precede the appearance of significant intracellular oxidative stress and may be due to alterations in the reduced status of critical membrane bound proteins. Exogenously administered thiols attenuate protein alterations via a localized increase in thiol availability without an increase in gross measures of intracellular thiol or glutathione content.

ISSN:1071-5762    

DOI:10.3109/10715769609088007

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

The oxidation of low density lipoprotein (LDL) was carried out aiming specifically at elucidating the anti-oxidant action ofα-tocopherol. Lipophilic and hydro-philic azo compounds and copper induced the oxidation of LDL similarly to give cholesterol ester and phosphatidylcholine hydroperoxides as major products. The antioxidant potency of a-tocopherol in LDL was much poorer than in homogeneous solution. Doxyl stearic acids were used as spin probe and incorporated in LDL. The rate of reduction of doxyl nitroxide in LDL by ascorbate decreased with increasing distance from the LDL surface. From the competition between the spin probe and a-tocopherol in scavenging radical, it was found that the efficacy of radical scavenging by a-tocopherol became smaller as the radical went deeper into the interior of LDL. On the other hand, 2,2,5,7,8-pentamethyl-6-chromal spared the spin label regardless of the position of nitroxide. The antioxidant activity of chromanols against LDL oxidation increased with decreasing length of isoprenoid side chain at the 2-position. All these results were interpreted by location and low mobility of a-tocopherol in LDL. The tocopherol mediated propagation was observed notably at low rate of radical flux, but this was suppressed by reductant such as ascorbic acid and ubiquinol.

ISSN:1071-5762    

DOI:10.3109/10715769609088008

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Although low density lipoprotein (LDL) susceptibility to oxidation is expected to be primarily related to its composition, the individual contributions of different constituents to its oxidizability remain unclear. The present study was undertaken to elucidate how different constituents of isolated LDL determine its susceptibility to oxidation induced by Cu2+under conditions close to those of the well-known Cu2+-oxidation assay (H. Esterbauer, G. Striegl, H. Puhl and M. Rotheneder (1989)Free Radical Research Communications, 6, 67–75). We characterized antioxidant, fatty acid and total lipid composition of human LDL from healthy donors (n= 22) and compared each with LDL oxidizability by Cu2+. LDL oxidizability was evaluated as oxidizability of antioxidant-containing LDL (rate of lipid peroxidation measured before total consumption of a-tocopherol, the major LDL antioxidant), oxidizability of antioxidant-depleted LDL (maximal rate of lipid peroxidation and maximal production of conjugated dienes within the propagation, antioxidant-depleted phase of oxidation) and overall LDL resistance to oxidation (duration of the lag-phase before the onset of the propagation phase). We found that the oxidizability of antioxidant-containing LDL correlated negatively with LDL content of ubiquinol-10 and free cholesterol, and positively with that of n-3 polyunsaturated fatty acids (PUFAs). LDL n-3 PUFAs, ubiquinol-10 and free cholesterol were the most important determinants of the oxidizability of antioxidant-containing LDL, contributing to about 35%, 25% and 25% of its total variability, respectively. Oxidizability of antioxidant-depleted LDL was largely determined by LDL PUFA content. The overall LDL resistance to oxidation correlated weakly with LDL chemical composition.α-Tocopherol was found to be only a minor contributor to the oxidizability of isolated LDL under oxidative conditions used (7.5 or 14 mol Cu2+/mol LDL), It appears that the oxidizability of antioxidant-containing LDL represents a parameter highly sensitive to changing LDL composition, whereas the overall LDL resistance to oxidation combines contributions from different LDL constituents more uniformly, being weaker sensitive to individual factors. It is suggested that PUFAs, ubiquinol-10 and free cholesterol are the most important determinants of LDL oxidizability by Cu2+.

ISSN:1071-5762    

DOI:10.3109/10715769609088009

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Reactive Oxygen and Oxidative Stress: A New Route for Tackling Disease? Scrip Report, anonymous, 1994 PJP Publications, UK.Non-Steroidal Anti-inflammatory Drugs: Mechanism and Clinical Uses Edited by Alan J. Lewis and Daniel E. Furst (Second edition) xii + 461 pagesMarcel Dekker: New York, 1994 ISBN 0 8247–8856–7Bioinorganic Chemistry: An Inorganic Perspective of Life Edited by Dimitris P. Kessissoglou NATO AS1 (Advanced Science Institutes), Series C: Mathematical and Physical Sciences Volume 459:1995Kluwer Academic Publishers: DordrechtISBN 0 7923 3380 2 xx + 415 pagesRegulatory Toxicology Edited by C.P. Chengelis, J.F. Holson and S.C. GadRaven Press: New York, 1995, pp. ix + 251 ISBN 0 781 701 910, $109.50Oxidative Stress and Aging Edited by R.G. Cutler; L. Packer, J. Bertram and A. MoriBirkhauser Verlag AG, 1995ISBN 3–7643–5039–3.£79, $124Neurotoxicology: Approaches and Methods Edited by L.W. Chang and W. Slikker Jr.Academic Press, San DiegoISBN 0–12–16 8055–X. $149.95 (£100 approx.)Radical Chemistry by M.J. PerkinsEllis Horwood Series in Organic Chemistry, Ellis Horwood Limited1994 pp. 182 ISBN 013 3209202.King's College London Immunopharmacology of Free Radical Species Edited by D. Blake and P.G. WinyardAcademic Press, London, pp. 301 ISBN 0121035204.£45.00.

ISSN:1071-5762    

DOI:10.3109/10715769609088010

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

ISSN:1071-5762    

DOI:10.3109/10715769609088011

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor