Effects of in vivo hyperoxia on erythrocytes. 3. In vivo peroxidation of erythrocyte lipid

Saturation diving; physiology and pathophysiology

In saturation diving, divers stay under pressure until most of their tissues are saturated with breathing gas. Divers spend a long time in isolation exposed to increased partial pressure of oxygen, potentially toxic gases, bacteria, and bubble formation during decompression combined with shift work and long periods of relative inactivity. Hyperoxia may lead to the production of reactive oxygen species (ROS) that interact with cell structures, causing damage to proteins, lipids, and nucleic acid. Vascular gas-bubble formation and hyperoxia may lead to dysfunction of the endothelium. The antioxidant status of the diver is an important mechanism in the protection against injury and is influenced both by diet and genetic factors. The factors mentioned above may lead to production of heat shock proteins (HSP) that also may have a negative effect on endothelial function. On the other hand, there is a great deal of evidence that HSPs may also have a "conditioning" effect, thus protecting against injury. As people age, their ability to produce antioxidants decreases. We do not currently know the capacity for antioxidant defense, but it is reasonable to assume that it has a limit. Many studies have linked ROS to disease states such as cancer, insulin resistance, diabetes mellitus, cardiovascular diseases, and atherosclerosis as well as to old age. However, ROS are also involved in a number of protective mechanisms, for instance immune defense, antibacterial action, vascular tone, and signal transduction. Low-grade oxidative stress can increase antioxidant production. While under pressure, divers change depth frequently. After such changes and at the end of the dive, divers must follow procedures to decompress safely. Decompression sickness (DCS) used to be one of the major causes of injury in saturation diving. Improved decompression procedures have significantly reduced the number of reported incidents; however, data indicate considerable underreporting of injuries. Furthermore, divers who are required to return to the surface quickly are under higher risk of serious injury as no adequate decompression procedures for such situations are available. Decompression also leads to the production of endothelial microparticles that may reduce endothelial function. As good endothelial function is a documented indicator of health that can be influenced by regular exercise, regular physical exercise is recommended for saturation divers. Nowadays, saturation diving is a reasonably safe and well controlled method for working under water. Until now, no long-term impact on health due to diving has been documented. However, we still have limited knowledge about the pathophysiologic mechanisms involved. In particular we know little about the effect of long exposure to hyperoxia and microparticles on the endothelium.

In vivo biochemical and gene expression analyses of the antioxidant activities and hypocholesterolaemic properties of Tamarindus indica fruit pulp extract

BACKGROUND

Tamarindus indica (T. indica) is a medicinal plant with many biological activities including anti-diabetic, hypolipidaemic and anti-bacterial activities. A recent study demonstrated the hypolipidaemic effect of T. indica fruit pulp in hamsters. However, the biochemical and molecular mechanisms responsible for these effects have not been fully elucidated. Hence, the aims of this study were to evaluate the antioxidant activities and potential hypocholesterolaemic properties of T. indica, using in vitro and in vivo approaches.

METHODOLOGY/PRINCIPAL FINDINGS

The in vitro study demonstrated that T. indica fruit pulp had significant amount of phenolic (244.9 ± 10.1 mg GAE/extract) and flavonoid (93.9 ± 2.6 mg RE/g extract) content and possessed antioxidant activities. In the in vivo study, hamsters fed with high-cholesterol diet for ten weeks showed elevated serum triglyceride, total cholesterol, HDL-C and LDL-C levels. Administration of T. indica fruit pulp to hypercholesterolaemic hamsters significantly lowered serum triglyceride, total cholesterol and LDL-C levels but had no effect on the HDL-C level. The lipid-lowering effect was accompanied with significant increase in the expression of Apo A1, Abcg5 and LDL receptor genes and significant decrease in the expression of HMG-CoA reductase and Mtp genes. Administration of T. indica fruit pulp to hypercholesterolaemic hamsters also protected against oxidative damage by increasing hepatic antioxidant enzymes, antioxidant activities and preventing hepatic lipid peroxidation.

CONCLUSION/SIGNIFICANCE

It is postulated that tamarind fruit pulp exerts its hypocholesterolaemic effect by increasing cholesterol efflux, enhancing LDL-C uptake and clearance, suppressing triglyceride accumulation and inhibiting cholesterol biosynthesis. T. indica fruit pulp has potential antioxidative effects and is potentially protective against diet-induced hypercholesterolaemia.

Hyperbaric oxygen reduces the progression and accelerates the regression of atherosclerosis in rabbits

We studied the effect of hyperbaric oxygen (HBO) treatment on the extent of diet-induced accumulation of lipid oxidation products in rabbit plasma and tissues, on plasma paraoxonase activity, and on the extent of progression and regression of atherosclerotic lesions in the rabbit aorta. HBO treatment of cholesterol-fed rabbits dramatically reduces the development of arterial lesions despite having little or no effect on plasma or individual lipoprotein cholesterol concentrations. Compared with no treatment in cholesterol-fed animals, HBO treatment also substantially reduces the accumulation of lipid oxidation products (conjugated dienes, trienes, and thiobarbituric acid-reactive substances) in plasma, in the low density lipoprotein and high density lipoprotein fractions of plasma, in the liver, and in the aortic tissues. In addition, HBO treatment prevents the decrease in plasma paraoxonase activity observed in rabbits fed cholesterol-rich diets. Similarly, in regression studies, HBO treatment has no effect on the rate of plasma (or lipoprotein) cholesterol decline but significantly accelerates aortic lesion regression compared with no treatment. Direct measures of aortic cholesterol content support these morphological observations. On the basis of these results, we conclude that repeated, but relatively short, exposure to HBO induces an antioxidant defense mechanism(s) that is responsible for retarding the development or accelerating the regression of atherosclerotic lesions.

Inhibition in vitro linoleic acid peroxidation and haemolysis by caffeoyltryptophan

Antioxidant activities of caffeoyltryptophan were investigated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging system, the superoxide anion generation system and the superoxide anion-mediated linoleic acid peroxidation system. At 10 microM, caffeoyltryptophan showed greater scavenging activity on DPPH than dl-alpha-tocopherol or ascorbic acid. DPPH radical scavenging activity of caffeoyltryptophan increased dose-dependently at concentrations ranging from 1 to 50 microM; 1 mol of caffeoyltryptophan reacted with ca 4 mol of radical. Caffeoyltryptophan caused 80% inhibition of superoxide anion generation at 50 microM. The inhibitory activity of caffeoyltryptophan was as strong as that of 5-caffeoylquinic acid. Caffeoyltryptophan inhibited the formation of conjugated diene from linoleic acid. The inhibitory activity increased in the order caffeic acid < 5-caffeoylquinic acid < caffeoyltryptophan < dl-alpha-tocopherol. Effects on the in vitro haemolysis and peroxidation of mouse erythrocytes induced by H2O2 were also examined. Caffeoyltryptophan exhibited strong inhibitory activities; Tryptophan was ineffective in these systems. These data suggest that caffeoyltryptophan may be a natural antioxidant in the human diet and, as such, may intervene in toxicological processes that are mediated by radical mechanisms.

Lipid peroxide and leukotriene B3 production in patients undergoing cardiopulmonary bypass

Cardiac surgery with cardiopulmonary bypass (CPB) is frequently associated with a complex array of post-operative clinical abnormalities, including low-output syndrome and pulmonary dysfunction. It has been reported that oxygen free radicals are one of the important factors causing reperfusion injury. To determine whether oxygen free radicals are produced during cardiac surgery, we studied nine patients anesthetized with high doses of fentanyl. Lipid peroxide (LPO) and leukotriene B₄ (LTB₄) levels increased significantly from 60 min after aortic ligation to 180 min after reperfusion (aortic declamping), compared with the levels before surgery, while superoxide dismutase (SOD) was not affected markedly. Creatine kinase (CK), CK muscle-brain (CK-MB), and neutrophils increased from 60 min after aortic declamping. Correlations were not observed between LPO and CK nor between LPO and CK-MB. These results suggest that free radicals are generated during cardiac surgery with cardiopulmonary bypass (CPB), but it is unclear whether free radicals cause tissue injury after cardiac surgery with CPB.

Decreased leukocyte deformability after acute cigarette smoking in humans

Acute cigarette smoking increases the sequestration of neutrophils in the lungs of humans. This may be due to the delayed transit of cells in the pulmonary microcirculation, which may result from a reduction in cell deformability as suggested by in vitro studies of smoke-exposed neutrophils. In order to support this hypothesis we wished to determine if a reduction in leukocyte deformability could be measured in whole blood exposed to smoke in vitro or in vivo. Whole blood filterability, which largely reflects leukocyte deformability, was measured as the pressure developed by filtration of diluted whole blood through a micropore membrane. Whole blood filtration pressures did not change when blood was exposed to smoke in vitro or in venous blood after acute smoking in vivo. However, arterial blood sampled from chronic smokers during acute smoking showed a consistent reduction in leukocyte deformability associated with a small increase in plasma elastase. To assess whether these changes were induced by oxidants in cigarette smoke, we measured the levels of the antioxidant glutathione (GSH), erythrocyte (RBC) membrane fragility, and products of lipid peroxidation in plasma and RBC in blood exposed to smoke in vivo and in vitro. No change in RBC lipid peroxidation or membrane fragility could be detected after in vitro smoke exposure, possibly because of the high antioxidant capacity of the RBC. However, reduced blood GSH levels and increased levels of lipid peroxidation products were detected in plasma, reflecting oxidant stress. In contrast, we were unable to detect evidence of an increased oxidant burden in blood after acute smoking in vivo, in either arterial or venous blood samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Vitamin E and oxidative stress

Oxidative stress can result from or be enhanced by a large variety of conditions, including nutritional imbalance, exposure to chemical and physical agents in the environment, strenuous physical activities, injury, and hereditary disorders. While many enzymes and compounds are involved in protecting cells from the adverse effects of oxidative stress, vitamin E occupies an important and unique position in the overall antioxidant defense. The antioxidant function of vitamin E is closely related to the status of many dietary components. Vitamin E-depleted animals are generally more susceptible to the adverse effects of environmental agents than supplemented animals. Also, vitamin E supplementation is beneficial to certain groups of the population. However, supplementing vitamin E in experimental subjects maintained on a nutritionally adequate diet does not always provide additional protection. Differential metabolic responses in various organs and differences in experimental conditions often contribute in the discrepancies in the literature. The lack of clear evidence for the occurrence of lipid peroxidation or antioxidant function of vitamin E in vivo can be attributed partly to the presence of active pathways for metabolizing hydroperoxides, aldehydes, and other oxidation products. Specific and sensitive techniques for measuring lipid peroxidation products in biological systems are essential for understanding the role of free radical-induced lipid peroxidation in tissue damage and antioxidant function of vitamin E in vivo.

Hemoglobin degradation, lipid peroxidation, and inhibition of Na+/K(+)-ATPase in rat erythrocytes exposed to acrylonitrile

The effect of acrylonitrile (VCN) on erythrocyte lipid metabolism was investigated in vitro in metabolically active red cells from male Sprague-Dawley rats containing three types of hemoglobins: oxyhemoglobin, methemoglobin, and carbon monoxyhemoglobin. VCN at the concentration of 10 mM rapidly depleted erythrocyte glutathione (GSH) (75% of control) and induced lipid peroxidation (274% of control). Degradation of oxy- and methemoglobin was directly proportional to the extent of lipid peroxidation (r = 0.89). Addition of glucose to the incubation medium decreased hemoglobin degradation while it slightly increased VCN-induced lipid peroxidation. The highest amount of lipid peroxidation occurred in erythrocytes containing carbon monoxyhemoglobin and glucose. In the isolated red cell membranes incubated with 10 mM VCN, the lipid peroxidation was 400% of controls. VCN (25 mM) noncompetitively inhibited erythrocyte membrane Na+/K(+)-ATPase activity and the degree of inhibition was inversely proportional to the reaction temperature (r = -0.88). These findings indicate that the VCN induced hemoglobin degradation and lipid peroxidation are two extremes of a spectrum of oxidative damage in red cells leading to a change in physical state of membrane structure causing inhibition of adenosine triphosphate (ATPase) activity.

Lipid peroxidation and superoxide dismutase activity in muscle and erythrocytes in adult muscular dystrophies and neurogenic atrophies

Lipid peroxidation (LP) and superoxide dismutase (SOD) activity were determined in erythrocytes and skeletal muscle obtained from patients with limb-girdle and facioscapulohumeral muscular dystrophies, neurogenic atrophies and from age-matched control subjects. Neither lipid peroxidation nor SOD activity in erythrocytes of patients differed from control values. SOD activity and LP in muscle specimens were also normal in types of neurogenic atrophy. Lipid peroxidation in the muscle from patients with adult types of muscular dystrophy had a tendency to be increased. The values were widely scattered, the highest being obtained in the older patients with long duration of disease.

Liposomes as membrane model for study of lipid peroxidation

This article describes the properties, production and characterization of liposomes with special reference to their use as membrane model for the study of lipid peroxidation. It presents briefly the methods that can be used for the assay of liposomal lipid peroxidation and brings out the special advantages these liposomes provide in elucidating the mechanism of lipid peroxidation by different physical and chemical agents. Studies involving liposomal lipid peroxidation by different agents and the consequent changes in the structure and function of liposomal membrane have been reviewed briefly.

Clinical evaluation of the microporous hollow fiber oxygenator

This report concerns a clinical evaluation for a newly devised hollow fiber oxygenator, Capiox II. It functions on a one-pump system, and is simple to set up and operate. This equipment was used for 118 patients undergoing cardiac surgery at Tokyo University Hospital from February 1982 through February 1983. The gas transfer capacity proved to be satisfactory. The employment of an air-oxygen blender prevented overoxygenation, and reasonable levels of PaO2 and PaCO2 were demonstrated with a FiO2 0.7, V/Q ratio 0.7 at normothermia. The destruction of platelets was much less with the use of this oxygenator, as compared to findings with the BOS-10. Hemolysis by Capiox II appeared to be lower than that by BOS-10, but the difference was not statistically significant. Differences were distinct in the amount of microbubbles; strikingly, no bubble was evidenced in Capiox II by the ultrasound bubble detector, during general procedures. We conclude that Capiox II is of excellent clinical value, and should be used especially for infants as well as adult patients with possible long perfusions. The merits and demerits of this equipment are given attention.

Lipid peroxidation and superoxide dismutase activity in muscle and erythrocytes in Duchenne muscular dystrophy

Lipid peroxidation and superoxide dismutase activity in muscle and erythrocytes obtained from patients with Duchenne muscular dystrophy (DMD) and controls matched for age and sex were determined. The lipid peroxidation was found to be significantly higher in muscle of the DMD patients but not in erythrocytes. The possible significance of the findings have been considered and discussed.

Effect of malondialdehyde, a product of lipid peroxidation, on the function and stability of hemoglobin

Malondialdehyde (MDA) was found to react with normal hemoglobin A (Hb A), forming a number of less cationic components which were detected by cellulose acetate electrophoresis and gel electrofocusing. All the modified components moved down the cation-exchange resin at a quicker rate than Hb A, and this chromatographic behavior of the modified components was similar to that of glycosylated Hb A. Some of these modified components were intermolecularly crosslinked, and showed fluorescence with an excitation maximum at 390 nm and an emission maximum at 460 nm. It is likely that MDA reacts nonspecifically with the epsilon-amino groups of lysine and N-terminal amino groups to produce aminoacrolein, crosslinks, and strongly fluorescent 1,4-dihydropyridine-3,5-dicarbaldehyde. Oxygen affinity of the modified hemoglobins was increased. The modified hemoglobins were more readily oxidized into met-form. Mechanical stability of Hb A was also decreased by the modification. These results suggest that a considerable conformational change in Hb A was induced by the treatment with MDA. Since MDA is generated in erythrocytes as a consequence of liquid peroxidation, MDA may react with intracellular Hb A and influence the function and the stability of hemoglobin.

The effect of spin traps on phenylhydrazine-induced haemolysis

Spin-trapping agents have been used to study the involvement of free radicals in phenylhydrazine-induced haemolysis. Spin traps were found to decrease the rate of oxygen uptake and the rate of haemoglobin oxidation in the reaction of phenylhydrazine with oxyhaemoglobin. Spin traps were also found to inhibit haemolysis and lipid peroxidation in phenylhydrazine-treated fresh human erythrocytes, with a concomitant production of phenyl radical spin adducts. Lipophilic spin traps were found to be more effective inhibitors of haemolysis than their hydrophilic analogues.

Selenium and vitamin E sufficiency in premature infants requiring total parenteral nutrition

A randomized prospective study of LBW infants was undertaken to evaluate the effect of parenteral lipid infusions upon their antioxidant systems. Ten babies received a parenteral nutrition regimen with lipid emulsion, and ten received a regimen without lipid. Although the addition of lipid emulsion to the total parenteral nutrition regimen led to a rise in vitamin E levels, the selenium levels fell in both groups. Neither group showed evidence of deficient antioxidant systems by the peroxide hemolysis test or thiobarbituric acid test. There did not seem to be any adverse effect of the lipid infusion upon the clinical course of the infants except for hyperlipidemia. There was a better weight gain in infants receiving lipid.

Determination of erythrocyte superoxide dismutase, catalase, glucose-6-phosphate dehydrogenase, reduced glutathione and malonyldialdehyde in uremia

Erythrocyte superoxide dismutase (SOD: EC 1.15.1.1), catalase (EC 1.15.1.6), glucose-6-phosphate dehydrogenase (G-6-PD: EC 1.1.1.49), reduced glutathione (GSH) and malonyldialdehyde (MDA) were studied in 27 patients with chronic and 11 patients with acute renal failure. A comparison with 15 age- and sex-matched healthy subjects showed that patients with both acute and chronic renal failure had significantly low G-6-PD (p less than 0.05) values whereas SOD, catalase and MDA showed significantly elevated levels (p less than 0.05). After adequate dialysis or renal transplantation the SOD, G-6-PD, catalase and MDA values returned to normal. The findings suggest that the erythrocyte SOD, catalase, and G-6-PD can undergo an adaptive alteration which however appears reversible.

Free radical initiation in proteins and amino acids by ionizing and ultraviolet radiations and lipid oxidation--part III: free radical transfer from oxidizing lipids

Parallels and similarities in chemical and functional damage to proteins by ionizing and uv radiations and oxidizing lipids have been recognized for some time. However, only recently have oxidizing lipids been shown directly by electron spin resonance to be radiomimetic also in their capacity for protein free radical production. Free radicals play a key role in the transformation of energy to molecular and cellular damage. It is thus of critical importance to elucidate the general mechanisms of free radical formation and reactions in proteins in order to understand protein involvement in various pathological conditions and in food deterioration. Accordingly, this review is a detailed comparison of gamma-radiation, UV radiation, and lipid oxidation for what is presently known concerning (1) the specific modes of energy deposition and free radical formation, (2) the free radicals formed in proteins and amino acids, and (3) the typical damage correlating with these radicals.

Increased erythrocyte lipid peroxidation in hereditary xerocytosis

Xerocytosis is a chronic hemolytic anemia with abnormal membrane function manifested by an increase in passive potassium permeability. Xerocytes demonstrate a greater susceptibility to hydrogen peroxide manifested by the production of malondialdehyde (MDA). Xerocyte membrane phospholipid and fatty acid analysis is normal except for a slight increase in phosphatidyl choline, a commensurate decrease in sphingomyelin, as well as a decrease in linoleic acid. Metabolism and glutathione stability are normal as well as plasma vitamin E levels in patients with xerocytosis. The increased susceptibility to oxidant stress is exaggerated in the "older aged" xerocyte population and correlated well with decreased intracellular potassium concentration.

Nitrogen dioxide inhalation and human blood biochemistry

Blood from ten young adult male humans, exposed to 1 ppm or 2 ppm nitrogen dioxide (NO2) for 2.5--3.0 hr, was examined for evidence of biochemical changes. The experiments lasted three days. The subjects entered an environmental chamber, performed mild exercise, and completed a series of measurements of pulmonary physiology while breathing filtered air. Blood samples were then taken and analyzed. This regimen was repeated on the second and third day, except that the chamber atmosphere now contained 1 ppm or 2 ppm NO2. Paired group analyses were performed on the data. A statistically significant decrease was observed in the activity of the erythrocyte membrane enzyme acetylcholinesterase at both NO2 levels. Levels of peroxidized red blood cell lipids showed statistically significant elevations after inhalation of 2 ppm NO2 but not 1 ppm. Glucose-6-phosphate dehydrogenase was significantly elevated only after the second 2-ppm NO2 exposure. Small but statistically significant decreases were observed in both hemoglobin and hematocrit values after exposure to both NO2 levels. The experiment was repeated with NO2, (i.e., three days of filtered air) to detect possible effects of the experimental procedure. Decreases were again seen in hemoglobin and hematocrit, and acetyecholinesterase, although of smaller magnitude than when NO2 was inhaled. Other data showed random variations that were not additive over the three-day sham exposure period. It was concluded that significant blood biochemical changes resulted from NO2 inhalation, although the three-day experimental regimen independently produced changes that account for some of the apparent response.

Biochemical response of squirrel monkeys to ozone

Biochemical studies were performed on blood and lung tissue of squirrel monkeys (Saimiri sciureus) following acute exposure to 0.75 ppm ozone (O3) for 4 h/d for 4 consecutive days. One group of animals was sacrificed at the end of the last exposure day and another group was sacrificed 4 d later after the last exposure. Evidence was sought for oxidation-induced changes known to occur in rodents when high levels of O3 are inhaled. A significant increase in red blood cell membrane fragility was observed, as well as significant decreases in red blood cell glutathione and erythrocyte acetylcholinesterase; however, the red blood cell enzymes, lactic acid dehydrogenase (LDH), and glucose-6-phosphate dehydrogenase (G6PDH) were not changed significantly. Lung tissue analysis showed that lipid peroxidation was markedly increased and tissue vitamin E levels were significantly decreased. The tissue enzymes G6PDH, glutathione reductase, and LDH significantly increased in activity. No significant changes were seen in either superoxide dismutase or malic acid dehydrogenase. The results of this experiment indicate that O3, or reaction products resulting from O3-tissue interaction in the lung, pass the air-blood barrier and are capable of producing biochemical changes in blood as well as in lung tissue.

Studies on vitamin E and selenium deficiency in young pigs. II. The hydrogen peroxide hemolysis test and the measure of red cell lipid peroxides as indices of vitamin E and selenium status

The usefulness of the hydrogen peroxide hemolysis test and the measure of red cell lipid peroxides as indices of vitamin E and selenium deficiency in swine has been evaluated. Results indicated that although the hydrogen peroxide hemolysis test may be of some indication of the vitamin E status, it is not a reliable index of vitamin E deficiency in swine, at least on an individual basis. In contrast, the measure of red cell lipid peroxides can be considered a reliable test for vitamin E deficiency in swine. The hydrogen peroxide hemolysis test and the red cell lipid peroxides were not significantly affected by selenium deficiency.

The effect of oxygen tension on the growth and metabolism of WI-38 cells

The effect of oxygen tension on cellular growth and metabolism was studied in actively growing WI-38 cells [greater than 90% labeled nuclei (LN)] grown under atmospheres containing 5% CO2 and various combinations of O2 and N2. Cells grown under a partial pressure of oxygen (PO2) of 7.8 +/- 3.5 mm Hg had a significantly slower growth rate, lower saturation densities and higher rates of glucose consumption and lactate production than did cells grown under a PO2 of 44 +/- 7 mm Hg. There were no significant differences in saturation density or the rates of glucose consumption or lactate production between cells grown under PO2 26 +/- 4 mm Hg, 44 +/- 7 mm Hg, or 134 +/- 11 mm Hg. Population doubling time was slightly prolonged at a PO2 of 134 mm Hg compared to a PO2 of 44 mm Hg. Cells grown under a PO2 of 291 +/- 25 mm Hg showed only 20-30% of the growth rate and 10-20% of the saturation density of cells grown under a PO2 of 134 mm Hg. Despite this reduced growth, cells grown under a PO2 of 291 mm Hg consumed four to six times as much glucose and produced four to six times as much lactate per cell as cells grown at a PO2 of 134 mm Hg. Cells grown under a PO2 of 560 +/- 38 mm Hg attached but did not proliferate. This toxic effect of oxygen on cell proliferation was reversible and was not due to an effect of oxygen on the media.

Spectrofluorescent detection of in vivo red cell lipid peroxidation in patients treated with diaminodiphenylsulfone

In the absence of vitamin E deficiency, red cell lipid peroxidation has not been clearly demonstrated in freshly drawn blood obtained from patients with various hemolytic anemias despite indirect evidence that oxidative decomposition of cell membrane unsaturated fatty acids occurs in these particular hemolytic states. Recent studies have indicated that malonaldehyde, a decomposition product of oxidized polyunsaturated fatty acids, is able to covalently cross-link the amino groups of protein or lipid resulting in a fluorescent compound. In the present study we have utilized spectrofluorescent technique to assess whether such fluorescence is present in red cell lipid extracts in association with lipid peroxidation. In vitro red cell lipid peroxidation produced by ultraviolet radiation or the oxidant gas ozone was associated with the development of a fluorescent peak (excitation maximum 360 nm; emission maximum 440 nm) in lipid-containing red cell extracts Similar fluorescence was observed after incubation of red cells with malonaldehyde or with malonaldehyde-containing extracts of peroxidized red cell lipid. Spectrofluorescent evaluation of chloroform: isopropanol extracts obtained from the freshly drawn red cells of six patients receiving the oxidant hemolytic drug diaminodiphenylsulfone also revealed a peak at 440 nm which ranged from 39 to 78 U. In contrast, the levels in samples obtained from 11 hematologically normal subjects were 17-27 fluorescence U. No evidence for an increase in blood levels of free malomaldehyde was observed using the 2-thiobarbituric acid test which is the most commonly performed assay of lipid peroxidation. Serum vitamin E levels were within the normal range. Density separation indicated that the bulk of the fluorescence was present in older red cells. A similar fluorescent peak was also observed in lipid-containing extracts of red cells obtained from rabbits repeatedly injected with phenylhydrazine. The finding of fluorescent spectra consistent with the cross-linking of aminolid by malonaldehyde in the red cells of patients receiving diaminodiphenylsulfone indicates that in vivo red cell lipid peroxidation does occur in the absence of vitamin E deficiency.

Superoxide dismutase (erythrocuprein) and free radicals in clinical chemistry

Erythrocuprein (superoxide dismutase) has recently been shown to have an enzymic function towards superoxide anions. The discovery of superoxide dismutase, its mode of action, and estimation are reviewed along with a brief introduction to oxygen activation and free-radical chemistry. The formation, activity, and destruction of oxygen free radicals in white blood cells, red blood cells, and subcellular particles are discussed. (a) The production of superoxide anions by white cells during phagocytosis is thought to be advantageous for the overall bactericidal event. (b) Normal red blood cells generate low levels of superoxide anions. Increased levels of free-radical production could play a significant role in accelerating cell ageing (haemolysis). (c) Subcellular particles produce superoxide anions. These as well as organic peroxides have been implicated in drug hydroxylation reactions involving cytochrome P-450.

Ozone and human blood

Statistically significant changes (P less than .05) were observed in erythrocytes (RBC) and sera of young adult human males following a single short-term exposure to 0.50 ppm ozone (O3) for 2 3/4 hours. The RBC membrane fragility, glucose-6-phosphate dehydrogenase (G-6-PDH) and lactate dehydrogenase (LDH) enzyme activities were increased, while RBC acetylcholinesterase (AcChase) activity and reduced glutathione (GSH) levels were decreased. The RBC glutathione reductase (GSSRase) activities were not significantly altered. Serum GSSRase activity, however, was significantly decreased while serum vitamin E, and lipid peroxidation levels were significantly increased. These alterations tend to disappear gradually, but were still detectable two weeks following exposure.

Oxidation of lipids and membranes II: Effects of oxidants on cerebral white matter homogenates

Bovine cerebral white matter homogenates were oxidized by various oxidizing solutions of equal molarity and subsequently extracted with water. Most of the oxidants tested (K-dichromate, FeCL3, H2O2, O2, and chloroperbenzoic, ascorbic, performic, and periodic acids) rendered the various myelin constituents less extractable than the constituents of unoxidized control homogenates. KMnO4, and to a lesser degree hemoglobin, rendered myelin constituents more extractable with water than those of the control homogenates. The findings indicate that most of the oxidants produced stabilization of the lamellar pattern, probably through cross-linking and polymerization. KMnO4 and hemoglobin caused labilization and breakdown of the membranous structure. Proof that stabilization of membranes is caused by some oxidants and that fragmentation occurs by the action of KMnO4 and hemoglobin was obtained by the light scattering technique and by electron microscopy of the oxidized homogenates. Evidence obtained indicated that formation of hydrophobic end groups during oxidation favors polymerization, while prevalence of hydrophilic groups is associated with fragmentation.

In vivo formation of H2O2 in red cells during exposure to hyperoxia

Chow-fed and tocopherol-deficient mice were given aminotriazole (AT), exposed to 100% O(2) at 60 pounds per square inch absolute for 1 hr (OHP), and red blood cells were assayed for catalase activity and lipid peroxide levels. A decrease of catalase activity (CA) in the presence of AT can be taken as evidence of excess formation or accumulation of H(2)O(2). No differences of CA were observed among chow-fed mice, with or without AT and/or OHP. Tocopherol-deficient mice with AT had lower CA (0.174+/-0.040) than chow-fed mice with AT (0.225+/-0.028) P < 0.01. Tocopherol-deficient mice with AT exposed to OHP had even lower CA, 0.137+/-0.024, P < 0.01.The data are consistent with the hypothesis that H(2)O(2) is formed or accumulated in excess in red cells of tocopherol-deficient mice, an effect that is enhanced in the presence of hyperoxia. They imply that tocopherol plays a role in the detoxification of H(2)O(2).

Erythropoietic protoporphyria: lipid peroxidation and red cell membrane damage associated with photohemolysis

The mechanism by which long wavelength ultraviolet light hemolyzes red cells obtained from patients with erythropoietic protoporphyria (EPP) was investigated. Previous studies had suggested that irradiation of these red cells with wavelengths of light capable of eliciting dermatological manifestations led to oxygen-dependent colloid osmotic hemolysis through the formation of peroxides. In the present report, lipid peroxidation during in vitro irradiation of EPP red cells with long ultraviolet light was demonstrated by: (a) the formation of 2-thiobarbituric acid reactants; (b) the presence of conjugated diene bonds in red cell lipid; and (c) the selective loss of unsaturated fatty acids proportional to the number of carbon-carbon double bonds in each. Irradiation of EPP red cells was also shown to result in the formation of hydrogen peroxide.Before photohemolysis there was a decline in cell membrane sulfhydryl groups and a loss in activity of the cell membrane enzyme acetylcholinesterase. These parameters provide further evidence suggesting that the cell membrane is a primary site of the photohemolytic effect of long ultraviolet light in EPP red cells. Further evaluation of the radiation-induced inactivation of EPP red cell acetylcholinesterase was performed by radiating mixtures containing bovine erythrocyte acetylcholinesterase and protoporphyrin IX. These studies revealed that the rate of decline in enzyme activity is accelerated by the addition of linoleic acid, an unsaturated fatty acid, but not by palmitic acid, a saturated fatty acid. Partial protection against both photohemolysis and acetylcholinesterase decline is provided by alpha-to-copherol. This lipid antioxidant loses its activity during the irradiation of EPP red cells suggesting that it is utilized in this process.