摘要:

A chemiluminescence (CL) flash kinetics on the addition of Fe2+ions into oxidized low density lipoprotein (LDL) suspension has been studied. LDL oxidation was carried out at 37°C without and in the presence of 5 or 50μM of Cu.2+It has been found that under certain experimental conditions (the addition of excess iron ions, more than 1 mM) the amplitude of CL flash depended almost linearly (1) on the concentration of oxidized LDL and (2) on the extent of LDL oxidation measured as diene conjugates (DC) and 2-thiobarbituric acid-reactive substance (TBARS) accumulation. The corresponding correlation coefficients were: for TBARS - 0.94 and for DC - 0.97, in the case of LDL autooxidation; 0.72 and 0.98, in the case of copper-induced LDL oxidation. A sensitivity of the CL method was shown to be significantly enhanced (by more than two orders) in the presence of CL sensitizer - 2, 3,5, 6-lH,4H-tetrahydro-9-(2′-benzoimidazolyl)-quinolizin-(9, 9a, 1 -gh)coumarin.

ISSN:1071-5762    

DOI:10.3109/10715769409145627

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

There is evidence that patients with adult respiratory distress syndrome are under severe oxidative stress that leads to molecular damage. Oxidative stress appears to be inherent in the disease process as well as an unfortunate complication of essential treatment with oxygen. Eight critically ill patients with an established diagnosis of adult respiratory distress syndrome requiring high inspired oxygen concentrations administered by ultra high frequency jet ventilation, were studied. Three patients survived (38%). For the group as a whole, there was evidence of increased protein damage, measured on serial plasma samples as an increase in protein carbonyls (meanßM, 1.41±0.09 nmol/mg protein), compared with Intensive Care Unit (ICU) controls (1.24±0.09 nmol/mg protein), and normal healthy controls (0.940±0.04 nmol/mg protein). Protein thiol groups were decreased in the ARDS group (4.56±0.50 nmol/mg protein) compared with ICU controls (5.5±0.27 nmol/mg protein), and the normal healthy controls (6.55±0.52 nmol/mg protein). However, when ARDS patients were grouped as survivors and non-survivors, total plasma protein levels were lower in survivors (53.9±2.15 mg/ml) compared with non-survivors (78.2±4.68 mg/ml); but the protein thiol content was significantly higher (p =<0.001) in survivors (6.24±0.09 nmol/mg protein) compared with non-survivors (3.56±0.16 nmol/mg protein). Serial plasma measurements of protein damage indicated two different patterns. Survivors had higher total plasma thiol values (protein corrected), which increased as the lung injury resolved, and failing protein carbonyl values. By contrast, non-survivors had low and failing protein thiols often accompanying rising carbonyls.We suggest that patients with adult respiratory distress syndrome undergo intermittent phases of severe oxidative stress during intensive care which can lead to protein damage, and that the protein thiol pattern may be a useful indicator of patients more likely to survive, the disease.

ISSN:1071-5762    

DOI:10.3109/10715769409145628

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

Patients with the acute lung injury syndrome ARDS are under oxidative stress from the disease and from treatment with high inspired oxygen concentrations. Oxidative stress can lead to molecular damage by a variety of reactive oxygen intermediates generated in the lung. In the present study we sequentially monitor changes in plasma total lipid linoleic acid fatty acid levels, using GC-MS, and express these as a function of changes in plasma protein thiol values. In nine out of eleven ARDS patients there was a relationship between loss of protein thiols and loss of total lipid linoleic acid. In three patients changes in protein thiols preceded changes in total lipid linoleic acid by several days. Parallel decreases in plasma total lipid fatty acid esters of linoleic acid and protein thiols are suggestive of oxidative stress leading to molecular damage.

ISSN:1071-5762    

DOI:10.3109/10715769409145629

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

A self-referencing and non-invasive Ca2+-sensitive vibrating electrode was used to assess the effects of hydrogen peroxide-induced oxidative challenges on the efflux and influx of calcium across the plasma membrane of single nerve cells cultured from abdominal ganglion ofAplysia californica. A reduced net efflux of Ca2+from the cell soma occurred immediately after the addition of hydrogen peroxide (0.0025 mM, 0.005 mM or 0.01 mM) to the culture medium, indicating damage to the cell membrane or Ca2+transport mechanism. There then followed a marked efflux, the extent and duration of which was related to the concentration of hydrogen peroxide used and which may reflect compensatory activity by the Ca2+regulatory mechanisms in the plasmalemma. No morphological changes were observed in cells challenged with 0.0025 mM hydrogen peroxide and the enhanced rate of Ca2+efflux rapidly decreased to pre-exposure values. Sustained and enhanced Ca2+effluxes from those cells exposed to 0.005 mM or 0.01 mM hydrogen peroxide were also consistent with regulatory pumping of Ca2+out of the cell although contraction and blebbing of neurites and swelling of the soma may indicate that a proportion of the efflux arose from release of Ca2+from disrupted intracellular stores. The vibrating electrode is a useful additional technique for the study of the pathogenesis of neurological conditions, as ionic fluxes across single nerve cells exposed to physiologically-relevant concentrations of free radicals can be monitored non-invasively for prolonged periods.

ISSN:1071-5762    

DOI:10.3109/10715769409145630

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

The ozone-mediated oxidation of thymidine was investigated on the basis of final product identification. The oxidation reaction gave rise to five major modified nucleosides which were isolated and characterised from extensive H NMR and mass spectrometry studies. The comparison with the current knowledge of the hydroxyl radical-mediated oxidation reactions of thymidine in aerated aqueous solution indicates that the formation of ozone oxidation products may be mostly explained in terms of initial generation of an ozonide. Indeed, the identified products obtained by ozonolysis of thymidine resulted from the opening of the pyrimidine C5-C5 bond.

ISSN:1071-5762    

DOI:10.3109/10715769409145631

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

The hydroxyl radical adducts of 5, 5 dimethyl-1-pyrolline-N-oxide (DMPO) and 3, 3,5, 5 tetramethyl-1-pyrolline-N-oxide (TMPO) formed in the presence of hydrogen peroxide and Fe are normally quite stable, but in the presence of 5–20 micromolar myoglobin their ESR signals decay rapidly. This decay probably reflects further oxidation of the adduct to nonparamgnetic products.The ESR signal of the hydroxyl radical adduct of 1-alpha-phenyl-tert-butyl nitrone (PBN) formed under similar conditions is subject to non-heme dependent attenuation, possibly via hydroxyl radical scavenging, but not to heme dependent decay. Hydrogen peroxide readily converts myoglobin to its ferryl (FeIV) derivative, and this centre may be responsible for the oxidation of the DMPO and TMPO adducts. The different behaviour of PBN may be due to differences in susceptibility to ferrylmyoglobin mediated oxidation, or to steric differences controlling access to the heme pocket of myoglobin, and is relevant to the choice of spin trap for biological experiments aimed at detecting hydroxyl radicals in the presence of myoglobin or other heme proteins.

ISSN:1071-5762    

DOI:10.3109/10715769409145632

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

Previous studies have raised the question of whether pentane is a normal constituent of human breath, since its concentrations in inspired room air and expired breath are often similar. Using a highly sensitive assay for volatile organic compounds, we studied 37 normal subjects in order to determine the alveolar gradient of pentane in their breath (i.e. concentration in alveolar breath minus concentration in the inspired air). The chemical identity of pentane was confirmed by mass spectroscopy. The alveolar gradient of pentane was zero±0.175 nmol/1 in 54.1 % of subjects, and distributed in an approximately bell-shaped curve. Determination of the alveolar gradient divided the normal subjects into three groups: the“passive equilibrators”who did not appear to excrete pentane in the breath (the majority),“metabolizers”who actively catabolized inhaled pentane, and“manufacturers”who excreted more pentane than they inhaled.

ISSN:1071-5762    

DOI:10.3109/10715769409145633

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

DNA and Free RadicalsHalliwell B. and Aruoma O.I. (Eds).Ellis Harwood: London,1993, p. 332 ISBN 0132220350.Lipids: The Continuing Challenge American Journal of Clinical Nutrition May 1993 Vol 57 NO 5(s)

ISSN:1071-5762    

DOI:10.3109/10715769409145634

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor