ISSN:1071-5762    

DOI:10.3109/10715769609088040

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

In rat kidney cortex mitochondria, 4-hydroxynonenal inhibits state 3 respiration as well as uncoupled respiration at micromolar concentrations. The inhibition is more distinct for NAD-linked than for FAD-linked respiration. 4-Hydroxynonenal increases the state 4 respiration. It is assumed that 4-hydroxynonenal behaves like a decoupling agent. 4-Hydroxynonenal augments the inhibitory effect of 2, 4-dinitrophenol observed at superoptimal concentrations. 4-Hydroxynonenal is metabolised by renal mitochondria, and 4-hydroxynonenoic acid is one of the metabolites generated. This metabolite is without effect on respiration at concentrations up to 50μM. Therefore, the effect of 4-hydroxynonenal on respiration is not mediated by this fatty acid derivative formed during respiratory measurements.

ISSN:1071-5762    

DOI:10.3109/10715769609088041

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Reduction of iron (IV) in ferrylmyoglobin in the presence of P-lactoglobulin in aqueous solution is the result of two parallel reactions: (i) a so-called autoreduction, and (ii) reduction byβ-lactoglobulin in a second-order-reaction resulting in bityrosine formation inβlactoglobulin. In the pH-region investigated (5.4–7.4), the rate of reduction increased for both reactions with decreasing pH. The second order-reaction had for non-denaturedβ-lactoglobulin the activation parameters: AH* = 45 kJ.mol-1and AS*= -93J mol-1.K-1at pH = 7.0 and ionic strength 0.16 (NaCl). Reduction of ferrylmyoglobin byβ-lactoglobulin denatured by heat (86°C for 3 min) or by hydrostatic pressure (300 MPa for 15 min) resulted in formation of higher molecular weight species as detected by size-exclusion chromatography and by SDS-PAGE. No molecular weight changes were observed for reduction of ferrylmyoglobin by native P-lactoglobulin. Detection of bityrosine in the nativeβ-lactoglobulin fraction after oxidation with ferrylmyoglobin indicated intra-molecular bityrosine formation. In heat-denaturedβ-lactoglobulin bityrosine formation could be of intra-molecular and/or of inter-molecular origin, the latter being confirmed by size- exclusion chromatography.

ISSN:1071-5762    

DOI:10.3109/10715769609088042

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Reactive oxygen species (ROS) andHelicobacter pylorihave been identified as pathogenic factors in several gastrointestinal disorders. Since little information is available regarding the mechanistic pathways ofH. pylori-induced gastric injury, the potential role of ROS was investigated. The induction of ROS in gastric cells (GC) byH. pyloriwas assessed using chemiluminescence, cytochromecreduction, nitrobluetetrazolium (NBT) reduction and lactate dehydrogenase (LDH) leakage. The dose-dependent protective abilities of selected ROS scavengers on LDH leakage were determined. Following incubation of GC with three strains ofH. pylori(1:1), approximately 5.7–8.0 and 3.8–4.3 fold increases were observed in cytochrome c and NBT reduction, respectively, demonstrating production of ROS. Enhanced chemiluminescence responses of 2.1–and 3.7-fold were observed following incubation of GC withH. pylori(ATCC 43504) at ratios of 1:1 and 1:10, respectively. Approximately 2.2–and 3.5-fold increases in LDH leakage were observed at GC:H.pylori(ATCC 43504) ratios of 1:1 and 1:10, respectively. Substantial inhibition of LDH leakage from GC in the presence of H.pyloriwas observed following co-incubations with selected ROS scavengers with cimetidine serving as the best chemoprotectant. The antioxidants and H2-receptor antagonists had no effect on growth ofH. pyloricells. This study demonstrates thatH. pyloriinduces enhanced production of ROS in GC, and enhances membrane damage.

ISSN:1071-5762    

DOI:10.3109/10715769609088043

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Maternal diabetes during pregnancy is associated with an increased rate of congenital malformations in the offspring. The exact molecular etiology of the disturbed embryogenesis is unknown, but an involvement of radical oxygen species in the teratological process has been suggested. Oxidative damage presupposes an imbalance between the activity of the free oxygen radicals and the antioxidant defence mechanisms on the cellular level. The aim of the present study was to investigate if maternal diabetesin vivo, or high glucosein vitroalters the expression of the free oxygen radical scavenging enzymes superoxide dismutase (CuZnSOD and MnSOD), catalase and glutathione peroxidase in rat embryos during late organogenesis. We studied offspring of normal and diabetic rats on gestational days 11 and 12, and also evaluated day-11 embryos after a 48 hour culture period in 10 m M or 50 mM glucose concentration. Both maternal diabetes and high glucose culture caused growth retardation and increased rate of congenital malformations in the embryos. The CuZnSOD and MnSOD enzymes were expressed on gestational day 11 and both CuZnSOD, MnSOD and catalase were expressed on day 12 with increased concentrations of MnSOD transcripts when challenged by a diabetic milieu. There was a good correlation between mRNA, protein, and activity levels, suggesting that the regulation of these enzymes occurs primarily at the pre-translational level. Maternal diabetesin vivoand high glucose concentrationin vitroinduced increased MnSOD expression, concomitant with increased total SOD activity, and a tentative decrease in catalase expression and activity in the embryos. These findings support the notion of enhanced oxidative stress in the embryo as an etiologic agent in diabetic teratogenesis.

ISSN:1071-5762    

DOI:10.3109/10715769609088044

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Diethyldithiocarbamate (DDC), a potent copper chelating agent, has long been used for the treatment of oxygen toxicity to the central nervous system, as an immunomodulator to treat cancer, and in HIV-infected patients. We evaluated the antioxidant properties of DDC, including its scavenging of reactive oxygen species, its reducing properties, its iron-chelating properties, and its protective effects on oxidant-induced damage to brain tissue, protein, human LDL, and DNA. It is found that DDC is a powerful reductant and antioxidant since it scavenges hypochlorous acid, hydroxyl radical and peroxynitrite; it chelates, then oxidizes ferrous ions; it blocks the generation of hydroxyl radicals and inhibits oxidative damage to deoxyribose, protein, DNA, and human LDL. These findings may provide an explanation for the apparent beneficial effects of DDC against oxidative stress-related diseases that have been observed in experimental and clinical studies.

ISSN:1071-5762    

DOI:10.3109/10715769609088045

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Ribonucleotide reductases catalyze the irreversible reductive formation of 2′-deoxyribonucleotides required for DNA replication and cell proliferation, and a radical mechanism was assumed to be involved in this reaction. In order to search for a radical in the aerobic manganese ribonucleotide reductase (Mn-RRase) by electron paramagnetic resonance (EPR) the native metal-containing 100 kDa B2 subunit was deliberately prepared from the wild type strainCoynebacterium ammoniagenesATCC 6872. Enrichment by 2′5′-ADP Sepharose 4B affinity chromatography, fast protein liquid chromatography (FPLC) with Superose 12 and concentration by vacuum evaporation allowed for the first time the detection of a stable free radical by EPR spectroscopy at 77 K. The EPR spectrum exhibits an easily saturable doublet of 1.8 mT splitting and a line width of 1.3 mT at g = 2.0040. The EPR signal intensity showed a clear correlation with the enzymatic activity upon long-time storage at ambient temperature (294 K) and inactivation by the specific RRase inhibitor hy-droxyurea (HU). This leads to the assumption of a protein-linked radical, with functional significance, in the metal-containing 100 kDa 82 subunit of the Mn-RRase ofCorynebacteriurn ammoniagenes.

ISSN:1071-5762    

DOI:10.3109/10715769609088046

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Forty-five mutant male ODs rats, unable to synthesize ascorbic acid, were fed nine diets containing 5, 50 or 250 mg of vitamin E/kg diet and 150,300 or 900 mg of vitamin C/kg diet for 21 days. The concentrations of vitamins C and E increased in liver and plasma in relation to the level of these vitamins in the diet. Vitamin C dietary supplementation increased the plasma vitamin E content at low levels of vitamin E intake, supporting the concept of anin vivosynergism between both antioxidant vitamins. Vitamin C, at the dietary levels studied, did not affect the lipid peroxidation. Vitamin E decreased liver and plasma endogenous levels of thiobarbituric acid-reactive substances and liver sensitivity to non-enzymatic lipid peroxidation. This was confirmed by a highly specific assay of lipid hydroperoxides using high performance liquid chromatography with chemiluminescence detection. The hepatic concentration of both phosphatidylcholine and phosphatidylethanolamine hydroperoxides decreased as the vitamin E content of the diet increased. The results show for the first time the capacity of vitamin E to protect against peroxidation of major phospho-lipidsin vivounder basal unstressed conditions.

ISSN:1071-5762    

DOI:10.3109/10715769609088047

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Oxidative Stress, Lipoproteins and Cardiovascular Dysfunction Edited by C. Rice-Evans and K.R. Bruckdorfer Portland Press Research Monograph VII, Portland Press London UKFree Radicals and Oxidative Stress: Environment, Drugs and Food Additives C. Rice-Evans, B. Halliwell, G.C. Hunt (Eds)Portland Press: London. 1995 pp. 276 ISBN 1855780690

ISSN:1071-5762    

DOI:10.3109/10715769609088048

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

ISSN:1071-5762    

DOI:10.3109/10715769609088049

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor