Fluorescence changes in human gamma-globulin induced by free-radical activity.

Low-intensity ultraviolet irradiation was used to generate free-radical activity in lipid-free human gamma-globulin. The changes were monitored by fluorescence spectroscopy and gel filtration chromatography. The pattern and the effect of thiol compounds, free-radical scavengers and antioxidants point to a free-radical-mediated process. Initial energy uptake was probably in the region of aromatic amino acid residues, followed by complex intramolecular rearrangements. Irradiation led to the formation of molecular species and complexes whose fluorescence characteristics were different from those of native gamma-globulin and indistinguishable from those observed in inflammatory exudates.

Platelet function and conjugated diene concentrations in diabetic and non-diabetic survivors of acute myocardial infarction.

STUDY OBJECTIVE: The aim was to compare platelet function in diabetic and non-diabetic survivors of acute myocardial infarction and to relate it to an index of free radical activity in these patients. DESIGN: In vivo and in vitro indices of platelet function and diene conjugate molar ratios were measured in diabetic and non-diabetic infarct survivors on admission to hospital and sequentially for 72 h. PATIENTS: The patients were 17 diabetics (age 61.9 years, range 32-74) and 12 non-diabetics (60.8 years, range 39-75) admitted to hospital with acute myocardial infarction confirmed according to WHO criteria. MEASUREMENTS AND MAIN RESULTS: Agonist induced platelet aggregation, beta thromboglobulin levels, and linoleic acid 18:2(9,11)/18:2(9,12) molar ratios did not differ between diabetic and non-diabetic patients on admission. Concentrations of adrenaline producing 50% maximum platelet aggregation (EC50) in whole blood on admission were lower than non-infarct controls in both patient groups. The EC50 values in platelet rich plasma in both groups fell during the 72 h following admission (increases in platelet sensitivity). beta Thromboglobulin concentrations fell following admission in the diabetic group. Diene conjugate molar ratios were higher at 12 h and 24 h compared to admission in diabetic patients. Increases in diene conjugate ratios between admission and 24 h correlated with peak aspartate transaminase levels in both patient groups. No correlations were observed between platelet aggregation, beta thromboglobulin levels, or diene conjugate molar ratios. CONCLUSIONS: During 72 h following myocardial infarction there is a reduction in platelet activation in vivo and an increase in platelet sensitivity to exogenous agonists in vitro. Free radical generated isomers of linoleic acid increase in relation to infarct size, but are unrelated to platelet function. There were no differences in platelet function between diabetic and non-diabetic subjects.

Effect of cardiopulmonary bypass on circulating concentrations of leucocyte elastase and free radical activity.

Circulating concentrations of leucocyte elastase and free radical activity were measured in 11 adults undergoing cardiopulmonary bypass. In all patients the bypass procedure was associated with pronounced changes in plasma elastase concentrations, and peak enzyme concentrations correlated closely with the duration of bypass (r = 0.91, p less than 0.001). Serial measurement of octadeca-9, 11-dienoic acid, a non-peroxide marker of free radical activity, showed significant changes only in the plasma free fatty acid fraction, suggesting a direct relation to the action of heparin rather than to the bypass procedure as such. These studies support the hypothesis that neutrophil activation plays a central role in the organ dysfunction that may complicate cardiopulmonary bypass and suggest that elastase release rather than free radical generation may be the appropriate marker of the event.

Identification of a diene conjugated component of human lipid as octadeca-9,11-dienoic acid.

The predominant diene conjugated acyl residue in triacylglycerols, cholesteryl esters and phospholipids in human serum was identified by high performance liquid chromatography and capillary gas chromatography-mass spectrometry. It is an octadeca -9,11-dienoic acid.

The nature of diene conjugation in human serum, bile and duodenal juice.

Diene-conjugated lipids have been located by HPLC in serum, bile and duodenal juice. Whether esterified or not the same predominant fatty acid is responsible for most of the diene conjugation in all of these biological fluids. Initial attempts to generate this fatty acid in pure lipid by classical lipid peroxidation in vitro were unsuccessful. Ultraviolet irradiation of free fatty acids in the presence of protein produced diene-conjugated lipids similar to those found in vivo. The predominant diene-conjugated fatty acid in vivo is an isomerised C18:2 compound.

Time-course of free radical activity during coronary artery operations with cardiopulmonary bypass.

Myocardial and pulmonary impairment after cardiopulmonary bypass may be caused by oxygen free radicals produced by reperfusion and by activated neutrophils. Free radical activity was assessed by assays for lipid peroxidation (thiobarbituric acid-reactive material) and phospholipid-esterified diene conjugation (18:2[9,11]/18:2[9,12] molar ratio) in 25 patients during coronary artery operations. Arterial blood samples were obtained before, during the ischemic period, and for 24 hours thereafter. There were no significant changes in free radical indices during the ischemic periods, but after cessation of bypass they increased significantly. Ten minutes after bypass thiobarbituric acid-reactive material rose from 96 (median; range 65 to 145) nmol/gm albumin to 138 (85 to 200) nmol/gm albumin (p < 0.001), and molar ratio rose from 2.23% (0.45% to 7.70%) to 2.51% (0.39% to 7.93%) (p < 0.02). Values of thiobarbituric acid-reactive material subsequently decreased, but molar ratio reached a peak at 4 hours after bypass, 2.64% (0.55% to 10.08%) (p < 0.001), thereafter returning to baseline. The postoperative increases in thiobarbituric acid-reactive material and in molar ratio were correlated (r = +0.53; p = 0.006). These increases in thiobarbituric acid-reactive material and in molar ratio were not related to age, preoperative left ventricular function, or the number of grafts performed. Increase in thiobarbituric acid-reactive material correlated with the duration of cardiopulmonary bypass (r = +0.43; p = 0.03). In 10 patients in whom cardiopulmonary bypass was performed using a bubble oxygenator, the increases in thiobarbituric acid-reactive material were significantly greater than in the 15 in whom a membrane oxygenator was used (p < 0.02). These data show that after apparently uncomplicated coronary operations with bypass there is an increase in lipid peroxidation and diene conjugation, indicating increased free radical activity. This increase varies between patients and does not relate to patient or surgical factors but may depend on the type of oxygenator employed during bypass.

Measurements of plasma zinc. I. In health and disease.

Zinc is an essential trace element. Previous methods of measuring zinc in clinical material have been difficult and reported findings must be treated with caution. Using atomic absorption spectroscopy it has been established that plasma zinc is one of the most uniform biochemical characteristics of normal adult blood. Sex and age differences in adult life are insignificant. Increased metabolic activity, on the other hand, induces a marked, immediate fall in plasma zinc level. The possible implications of this are discussed. Zinc levels in patients with diabetes mellitus, cardiovascular disease, and anaemia due to acute blood loss have been within normal limits. Plasma zinc is low in certain types of liver disease.

Measurements of plasma zinc. II. In malignant disease.

The plasma zinc and plasma copper was estimated in 81 patients with malignant disease. There was a striking decrease in plasma zinc levels in carcinoma of bronchus compared both with normals and most other types of malignancy.

Reduced oxidase activity in the caeruloplasmin of two families with Wilson's disease.

Caeruloplasmin has been determined immunologically and by coper oxidase activity in 25 normal subjects, 20 patients with Wilson's disease, and 80 patients with chronic liver disease. Repeated estimation in four patients with Wilson's disease and two heterozygous mothers from two families revealed a consistent reduction in the copper oxidase activity of caeruloplasmin (12-32 units copper oxidase activity/mg caeruloplasmin) relative to the values obtained in normal subjects, patients with chronic liver disease, and other Wilson's disease patients (mean 65-79 units/mg). It is suggested that the functional abnormality in caeruloplasmin observed in these two families is an inherited variant, which does not appear to be due to the presence of a serum inhibitor of copper oxidase.

The relationship between erythrocyte superoxide dismutase activity and erythrocyte copper levels in normal subjects and in patients with rheumatoid arthritis.

A quantitative assay for erythrocyte superoxide dismutase activity using the xanthine-xanthine oxidase-nitro blue tetrazolium system which is applicable to clinical material is described. The in-batch precision of the method is 3.5% and the between-batch precision is 8.8%. Employing this assay, erthrocyte superoxide dismutase activities were measured in 50 normal subjects and in 50 patients with rheumatoid arthritis. There was no significant correlatiion between superoxide dismutase activity and erthrocyte copper concentration. Erythrocyte copper was lower in female rheumatoid patients than in normals. This difference was not accompanied by a difference in superoxide dismutase activity.

Recognition of cervical neoplasia by the estimation of a free-radical reaction product (octadeca-9,11-dienoic acid) in biopsy material.

Linoleic acid (18:2(9,12)) and its diene-conjugated isomer (18:2(9,11)) were measured in 65 cervical biopsy samples. Both the 18:2(9,11) concentration and the 18:2(9,11)/18:2(9,12) molar ratio showed highly significant differences between the normal and precancerous groups. Both showed a further significant increase in 4 invasive carcinomas. The findings in histologically normal areas from organs with precancer correlated significantly with the results in the precancerous lesions.

Recognition of cervical neoplasia by the estimation of a free-radical reaction product (octadeca-9,11-dienoic acid) in exfoliated cells.

The molar ratio between a diene-conjugated linoleic-acid isomer (18:2(9,11)) and the parent linoleic acid (18:2(9,12)), both esterified as phospholipids, was significantly different in exfoliated cells from normal cervices and from cervices with colposcopic and cytological evidence of precancer. The measurement may provide a simple and perhaps improved alternative to cytological screening.

Aberrant free radical activity in cystic fibrosis.

It has been suggested that the molar ratio of octadeca 9,11 dienoic acid to linoleic acid in biological material provides an index of activity along the non-peroxide pathway of a free radical attack on polyunsaturated fatty acids. In 17 adults with cystic fibrosis the 'molar ratio' in nasal epithelial cells--a recognised target of the disease--exceeded that in 20 controls (median 2.09%, range 1.70-3.01% versus 1.56, 0.92-2.23%, p = 0.0002). The difference was also apparent, although less stark, upon analysis of serum in a further 22 CF patients (2.48%, 1.60-5.24%) and 25 controls (1.96%, 0.81-3.90%, p = 0.0348). There was no correlation between the 'molar ratio' and blood white cell count or erythrocyte sedimentation rate, severity of lung or liver disease, indicating that the raised values are a primary feature, rather than reflecting disease severity. Aberrant free radical activity may underlie cellular dysfunction in cystic fibrosis.

The experimental and clinical pathology of diene conjugation.

The simple spectroscopic measurement of diene conjugation has long been an established but somewhat problematic marker of free-radical activity in biological systems. The main diene-conjugated compounds in human tissues and tissue fluids have now been identified as esters of octadeca-9,11-dienoic acid (18:2(9,11)), a non-peroxide isomer of linoleic acid (18:2(9,12)); and a range of high-performance liquid chromatographic methods has been developed for their detection and measurement. Significant abnormalities of phospholipid-esterified 18:2(9,11) have been found in the serum of chronic alcoholics and in paraquat poisoning and of non-esterified 18:2(9,11) in lipolytic states. The phospholipid-esterified 18:2(9,11) is increased in the bile of patients with pancreatic disease. In exfoliated cells from the cervix uteri an abnormal molar ratio between phospholipid-esterified 18:2(9,11) and 18:2(9,12) may prove to be the most sensitive biochemical marker of precancerous change.

A method for the measurement of a diene-conjugated derivative of linoleic acid, 18:2(9,11), in serum phospholipid, and possible origins.

A method is described for the measurement of a diene-conjugated derivative of linoleic acid, 18:2(9,11), in the phospholipid fraction of serum. The method is based on enzymatic hydrolysis, solid-phase sample preparation, and high-performance liquid chromatography (HPLC). Phospholipid esterified 18:2(9,11) can be detected in serum from normal individuals, and a provisional normal range is provided. The possible origins of 18:2(9,11) and the potential application of this method to the measurement of free radical damage to linoleic acid in vivo is discussed.

Serum antioxidant activity in normal and abnormal subjects.

Serum oxidant activity (AOA) was correlated with the serum caeruloplasmin and serum copper concentration and with the total and available serum iron-binding capacity in 313 normal and abnormal subjects. In all groups except in patients with Wilson's disease (hepatolenticular degeneration) there was a highly significant direct correlation between serum AOA and serum caeruloplasmin concentration. A statistically significant direct correlation between serum AOA and the available iron-binding capacity of serum was found only in normal subjects and in children with thalassemia major and iron overload. There was no correlation between serum AOA and the serum tocopherol concentration in any of the groups studied.

Free radical oxidation (peroxidation)products in plasma in normal and abnormal pregnancy.

Using recently developed methods for measuring free-radical oxidation products in biological material, plasma extracts were studied in 24 women in the first two trimesters of pregnancy, in 124 women in the third trimester of pregnancy, in 20 women with pre-eclamptic toxaemia (PET), and in a control group. There was a significant progressive rise of two groups of free-radical oxidation products throughout pregnancy and a significantly greater rise in PET. In women whose diastolic blood pressure rose to above 70 mmHg there was a highly significant relation between two groups of free-radical reaction products and blood pressure.

Free-radical reaction in biological systems.

Free radicals are a highly reactive chemical species which differ from all other species in possessing an unpaired electron. Although free-radical activity in living systems is energetically improbable, recent work suggests that a number of important biological processes depend on it. In contrast to enzymic metabolism these free-radical processes tend to be non-cyclic, irreversible, non-homoeostatic, and energetically wasteful. For the organism as a whole they may nevertheless have considerable survival value. Free radicals are too short-lived to be demonstrable in tissues; but methodological advances are leading to the detection and measurement of characteristic free-radical reaction products. The findings suggest that free-radical activity is not only a potential cause but also a common, perhaps invariable, consequence of cell damage. It is possible that some of the secondary products of free-radical reactions may help to regulate the body's local and systemic response to injury.