Serum malondialdehyde-like material (MDA-LM) in acute myocardial infarction

Fibrin Clot Formation under Oxidative Stress Conditions

During coagulation, the soluble fibrinogen is converted into insoluble fibrin. Fibrinogen is a multifunctional plasma protein, which is essential for hemostasis. Various oxidative posttranslational modifications influence fibrinogen structure as well as interactions between various partners in the coagulation process. The aim was to examine the effects of oxidative stress conditions on fibrin clot formation in arterial atherothrombotic disorders. We studied the changes in in vitro fibrin network formation in three groups of patients-with acute coronary syndrome (ACS), with significant carotid artery stenosis (SCAS), and with acute ischemic stroke (AIS), as well as a control group. The level of oxidative stress marker malondialdehyde measured by LC-MS/MS was higher in SCAS and AIS patients compared with controls. Turbidic methods revealed a higher final optical density and a prolonged lysis time in the clots of these patients. Electron microscopy was used to visualize changes in the in vitro-formed fibrin network. Fibers from patients with AIS were significantly thicker in comparison with control and ACS fibers. The number of fibrin fibers in patients with AIS was significantly lower in comparison with ACS and control groups. Thus, oxidative stress-mediated changes in fibrin clot formation, structure and dissolution may affect the effectiveness of thrombolytic therapy.

Lipidomics of Bioactive Lipids in Acute Coronary Syndromes

Acute coronary syndrome (ACS) refers to ischemic conditions that occur as a result of atherosclerotic plaque rupture and thrombus formation. It has been shown that lipid peroxidation may cause plaque instability by inducing inflammation, apoptosis, and neovascularization. There is some evidence showing that these oxidized lipids may have a prognostic value in ACS. For instance, higher levels of oxidized phospholipids on apo B-100 lipoproteins (OxPL/apoB) predicted cardiovascular events independent of traditional risk factors, C-reactive protein (hsCRP), and the Framingham Risk Score (FRS). A recent cross-sectional study showed that levels of oxylipins, namely 8,9-DiHETrE and 16-HETE, were significantly associated with cardiovascular and cerebrovascular events, respectively. They found that with every 1 nmol/L increase in the concentrations of 8,9-DiHETrE, the odds of ACS increased by 454-fold. As lipid peroxidation makes heterogonous pools of secondary products, therefore, rapid multi-analyte quantification methods are needed for their assessment. Conventional lipid assessment methods such as chemical reagents or immunoassays lack specificity and sensitivity. Lipidomics may provide another layer of a detailed molecular level to lipid assessment, which may eventually lead to exploring novel biomarkers and/or new treatment options. Here, we will briefly review the lipidomics of bioactive lipids in ACS.

Effects of the oxidative stress and genetic changes in varicose vein patients

Background

Etiology of the varicose veins is still partly known. It has been proposed that varicose veins formation might be a cause of the oxidative stress and/or cause from genetical reasons.

Method

The levels of antioxidant defense system enzymes, superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase, and an oxidative stress indicator, malondialdehyde, were measured in saphenous vein samples of varicose veins patients. Additionally, genetical polymorphism of glutathione S-transferase theta-1 has been studied.

Result

In this study, measurements revealed significant increase in catalase and malondialdehyde levels in the patient group, whereas superoxide dismutase and glutathione peroxidase and glutathione S-transferase enzyme activity and comparison of the null mutation frequency in the glutathione S-transferase theta-1 gene did not show a statistically significant difference.

Conclusion

We propose that the increase in catalase and malondialdehyde activities in our patient group may be related to each other. Increase in catalase levels, an antioxidant enzyme might be a compensatory response to the increase in malondialdehyde levels, an oxidative molecule.

Malondialdehyde (MDA) – product of lipid peroxidation as marker of homeostasis disorders and aging

Dialdehyd malonowy (MDA) w organizmie człowieka pochodzi z dwóch źródeł: spożywanego pokarmu i peroksydacji lipidów występujących w tkankach. Powstawanie MDA, a także wielkość i szybkość utleniania lipidów w tkankach organizmów żywych, zależy od wielu czynników endo- i egzogennych. Produkty peroksydacji lipidów, szczególnie MDA, wykazują właściwości cytotoksyczne, mutagenne i rakotwórcze. Mogą one również hamować enzymy związane z obroną komórki przed stresem oksydacyjnym. Mogą nie tylko przyczyniać się do rozwoju wielu chorób, ale stanowią również część procesu starzenia się. Organizm broni się w pewnym stopniu przed działaniem wolnych rodników, neutralizując je. Głównym źródłem przeciwutleniaczy jest żywność – produkty pochodzenia roślinnego. Styl życia, na który składają się dieta i aktywność fizyczna, jest ważnym elementem w zachowaniu zdrowia rozumianego jako dobre samopoczucie fizyczne i psychiczne. Nawyki żywieniowe i dieta bogata w przeciwutleniacze są modyfikowalnymi czynnikami, które nie tylko zapobiegają chorobom związanym z wiekiem, ale także opóźniają procesy starzenia.

Characterization of the magnitude and mechanism of aldehyde oxidase-mediated nitric oxide production from nitrite

Aldehyde oxidase (AO) is a cytosolic enzyme with an important role in drug and xenobiotic metabolism. Although AO has structural similarity to bacterial nitrite reductases, it is unknown whether AO-catalyzed nitrite reduction can be an important source of NO. The mechanism, magnitude, and quantitative importance of AO-mediated nitrite reduction in tissues have not been reported. To investigate this pathway and its quantitative importance, EPR spectroscopy, chemiluminescence NO analyzer, and immunoassays of cGMP formation were performed. The kinetics and magnitude of AO-dependent NO formation were characterized. In the presence of typical aldehyde substrates or NADH, AO reduced nitrite to NO. Kinetics of AO-catalyzed nitrite reduction followed Michaelis-Menten kinetics under anaerobic conditions. Under physiological conditions, nitrite levels are far below its measured K(m) value in the presence of either the flavin site electron donor NADH or molybdenum site aldehyde electron donors. Under aerobic conditions with the FAD site-binding substrate, NADH, AO-mediated NO production was largely maintained, although with aldehyde substrates oxygen-dependent inhibition was seen. Oxygen tension, substrate, and pH levels were important regulators of AO-catalyzed NO generation. From kinetic data, it was determined that during ischemia hepatic, pulmonary, or myocardial AO and nitrite levels were sufficient to result in NO generation comparable to or exceeding maximal production by constitutive NO synthases. Thus, AO-catalyzed nitrite reduction can be an important source of NO generation, and its NO production will be further increased by therapeutic administration of nitrite.

Characterization of superoxide production from aldehyde oxidase: an important source of oxidants in biological tissues

Aldehyde oxidase, a molybdoflavoenzyme that plays an important role in aldehyde biotransformation, requires oxygen as substrate and produces reduced oxygen species. However, little information is available regarding its importance in cellular redox stress. Therefore, studies were undertaken to characterize its superoxide and hydrogen peroxide production. Aldehyde oxidase was purified to >98% purity and exhibited a single band at approximately 290 kDa on native polyacrylamide gradient gel electrophoresis. Superoxide generation was measured and quantitated by cytochrome c reduction and EPR spin trapping with p-dimethyl aminocinnamaldehyde as reducing substrate. Prominent superoxide generation was observed with an initial rate of 295 nmol min(-1) mg(-1). Electrochemical measurements of oxygen consumption and hydrogen peroxide formation yielded values of 650 and 355 nmol min(-1) mg(-1). In view of the ubiquitous distribution of aldehydes in tissues, aldehyde oxidase can be an important basal source of superoxide that would be enhanced in disease settings where cellular aldehyde levels are increased.

Lipid peroxidation in workers exposed to aluminium, gallium, indium, arsenic, and antimony in the optoelectronic industry

OBJECTIVE

The objective of this study was to investigate whether exposure to aluminum, gallium, indium, arsenic, and antimony induces lipid peroxidation in humans.

METHODS

Whole blood and urine levels of 103 exposed electronic industry workers and 67 referents were analyzed by use of inductively coupled plasma mass spectrometry. Malondialdehyde (MDA), the product of lipid peroxidation, was determined by high-performance liquid chromatography.

RESULTS

The mean plasma MDA level in the 103 workers was significantly higher than that in 67 referents. The levels of MDA in the exposed workers were correlated significantly with the levels of urinary gallium and arsenic.

CONCLUSIONS

Malondialdehyde as an index of lipid peroxidation can be induced by gallium and arsenic exposure. By reducing exposure to these metals, biologic effects such as lipid peroxidation may also be diminished.

Malondialdehyde, a major endogenous lipid peroxidation product, sensitizes human cells to UV- and BPDE-induced killing and mutagenesis through inhibition of nucleotide excision repair

Aldehydes are ubiquitous contaminants in the human environment. Intracellular aldehydes are mainly derived from the metabolism of polyunsaturated fatty acids and from lipid peroxidation, which is significantly elevated under oxidative stress conditions. Oxidative stress has long been suspected to be involved in many disease processes, including carcinogenesis, neurodegeneration and aging, but its mechanisms are largely unknown. Aldehydes are reactive not only toward nucleic acids but also to many amino acids, and these aldehyde-protein interactions have been suspected of affecting many cellular functions, including DNA repair. To test this possibility we determined the effect of malondialdehyde (MDA), one of the most abundant intracellular aldehyde, on ultraviolet (UV) light- and benzo(a)pyrene diol epoxide (BPDE)-induced cytotoxicity and mutagenesis in human cells. We found that MDA treatment greatly sensitized cells to both UV- and BPDE-induced cell killing and that, MDA pre-treatment significantly enhanced UV-induced mutagenesis. Using in vitro DNA repair synthesis and host cell reactivation assays we found that MDA treatment of cells greatly inhibited nucleotide excision repair for both and UV light- and BPDE-induced DNA damage. Further experiments raise the possibility that the inhibitory effect on nucleotide excision repair is mainly caused by the direct interaction of MDA with cellular repair proteins. Together these results strongly suggest that intracellular aldehydes play an important role in oxidative stress-related mutagenesis and carcinogenesis through their inhibitory effect on DNA repair mechanisms as well as on induction of DNA damage.

Potential role of oxidized lipids and lipoproteins in antioxidant defense

The atherogenic oxidative modification of low-density lipoprotein is suggested to occur in the aortic intima. There is reasonable evidence to suggest that antioxidants might be beneficial in preventing or retarding the progression of atherosclerosis. Exercise, estrogens, and substitution of polyunsaturated fat for saturated fat are beneficial in the prevention of atherosclerosis. Yet, paradoxically, they are capable of inducing an oxidative stress. To reconcile with this paradox, we postulate that under certain conditions an oxidative stress might be beneficial by inducing antioxidant enzymes in arterial cells. However, those with genetic deficiency in antioxidant enzymes or those who poorly respond to oxidative stress or those with overwhelming plasma oxidative stress might need additional antioxidant protection.

Linoleic acid peroxidation--the dominant lipid peroxidation process in low density lipoprotein--and its relationship to chronic diseases

Modern separation and identification methods enable detailed insight in lipid peroxidation (LPO) processes. The following deductions can be made: (1) Cell injury activates enzymes: lipoxygenases generate lipid hydroperoxides (LOOHs), proteases liberate Fe ions--these two processes are prerequisites to produce radicals. (2) Radicals attack any activated CH2-group of polyunsaturated fatty acids (PUFAs) with about a similar probability. Since linoleic acid (LA) is the most abundant PUFA in mammals, its LPO products dominate. (3) LOOHs are easily reduced in biological surroundings to corresponding hydroxy acids (LOHs). LOHs derived from LA, hydroxyoctadecadienoic acids (HODEs), surmount other markers of LPO. HODEs are of high physiological relevance. (4) In some diseases characterized by inflammation or cell injury HODEs are present in low density lipoproteins (LDL) at 10-100 higher concentration, compared to LDL from healthy individuals.

Strong increase in hydroxy fatty acids derived from linoleic acid in human low density lipoproteins of atherosclerotic patients

Linoleic acid is the most abundant fatty acid in human low density lipoproteins (LDL). Oxidation of LDL transforms linoleic acid to hydroperoxyderivatives. These are converted to 9-hydroxy-10,12-octadecadienoic acid (9-HODE) and 13-hydroxy-9,11-octadecadienoic acid (13-HODE). 9-HODE is much more abundant in oxidized LDL than other lipid peroxidation products and therefore an indicator of lipid peroxidation (LPO). In this study the 9-HODE content in the LDL of 19 obviously healthy volunteers and 17 atherosclerotic patients was investigated. The level of 9-HODE obtained from LDL of young atherosclerotic patients (aged 36-47 years) was increased by a factor of 20 when compared with samples from healthy volunteers of the same age group. The content of 9-HODE in the LDL of atherosclerotic patients aged between 69 and 94 years increased 30-100 fold when compared with young healthy individuals, but when compared with 'healthy' individuals of the same age group it was only 2-3 fold increased. Obviously, as individuals grow older LDL becomes more and more oxidized. Consequently, assuming that LDL oxidation is a precondition for atherosclerosis--older individuals will suffer from atherosclerosis, even if no easy detectable visible signs of this disease are recognizable. According to 9-HODE determination, the onset of the disease starts slowly in most individuals at around 50 years of age.

Lower lipid peroxide levels in practitioners of the Transcendental Meditation program

OBJECTIVE

Oxidative stress or free radical activity may contribute to the pathophysiology of atherosclerosis and other chronic diseases associated with aging. Because psychosocial stress has been shown to increase oxidative stress, we conducted an exploratory study to investigate the effects of stress reduction with the Transcendental Meditation program on serum lipid peroxide levels in elderly subjects.

METHOD

Forty-one normally healthy subjects (aged 56 to 74 years, average 67 years) were recruited from the same Midwest city. Eighteen were long-term practitioners of the TM program (average 16.5 years). Twenty-three controls were not practicing a formal stress management technique. Venous blood samples were analyzed for lipid peroxides by the TBARS assay. A dietary questionnaire was used to assess fat intake, red meat consumption, antioxidant vitamin supplementation, and smoking. Differences between groups and subgroups were analyzed by t test, and correlations.

RESULTS

Significantly lower serum levels of lipid peroxides were found in the TM practitioners compared with controls (-15%, p = .026). No significant differences were found between groups on smoking, fat intake, or vitamin supplementation. TM practitioners also had lower red meat consumption but matched subgroup analysis and partial correlations did not confirm a relationship between red meat intake and lipid peroxide levels.

CONCLUSIONS

These preliminary findings suggest that lower serum lipid peroxide levels may be associated with stress reduction using the Transcendental Meditation technique. Prospective controlled trials are needed to confirm that this effect is because of TM practice rather than other lifestyle factors, such as diet.

Serum total antioxidant activity after myocardial infarction

Serum total antioxidant activity (TAA), albumin and uric acid were measured on admission, and for the next 2 days in 56 patients suffering myocardial infarction, 20 of whom received streptokinase. The 'antioxidant gap', the difference between the serum TAA and the sum of the serum albumin and uric acid activity, was calculated. No significant changes in serum total antioxidant activity were observed in either group of patients between admission, day 1 and day 2. However, a decline in the 'antioxidant gap' after myocardial infarction was associated with a significantly higher mortality.

Lipid abnormalities of erythrocyte membranes in hemodialysis patients with chronic renal failure

Lipids in erythrocyte membranes from 16 hemodialysis patients and 16 healthy volunteers were studied using gas chromatographic mass spectrometry. 7-keto cholestadiene was first reported in this study. The ratios of 7-keto cholestadiene to cholesterol, the ratios of arachidonate to cholesterol and the ratios of dochosahexanate to cholesterol in peak heights of chromatograms were measured in both groups as the markers of lipid peroxidation. Higher 7-keto cholestadiene/cholesterol ratios and lower arachidonate/cholesterol and dochosahexanate/cholesterol ratios were significantly observed in hemodialysis patients compared with healthy subjects. Our results are evidence that hemodialysis patients are exposed to much oxidative stress. It has been suggested that, during hemodialysis, leukocytes are activated by contract with non-physiological surfaces of the blood line tubing and produce oxygen free radicals. Oxygen free radicals attach cholesterol, arachidonate and dochosahexanate to produce lipid peroxides. In this study, this cell activation may be responsible for the increased lipid peroxidation of hemodialysis patients, 7-Keto cholestadiene, arachidonate and dochosahexanate can be used as markers of lipid peroxidation in hemodialysis patients.

Trace elements and lipid peroxidation in uremic patients on hemodialysis

Trace elements and lipid peroxidation in 26 patients with chronic renal failure treated with hemodialysis and 25 healthy subjects were observed. Both plasma and erythrocyte trace elements and plasma malon dialdehyde (MDA) were examined immediately before and after hemodialysis. Increased levels of plasma Cu, MDA, and erythrocyte Pb, Mn, Zn, and a significantly decreased plasma Se, Zn, and erythrocyte Se were found in patients before hemodialysis. After a single hemodialysis, erythrocyte Mn, Cu, Zn, and plasma Cu, Al, and MDA were significantly increased whereas both plasma and erythrocyte Se were lower in patients than in healthy subjects. The level of MDA was not significantly changed during the single hemodialysis. Both plasma and erythrocyte Zn levels and plasma Cu and Al were significantly higher after hemodialysis than before hemodialysis. In conclusion, levels of trace elements are altered by hemodialysis, which may increase patient susceptibility to lipid peroxidation in uremia.

Assessment of radical activity during the acute phase of myocardial infarction following fibrinolysis: utility of assaying plasma malondialdehyde

Numerous experimental and clinical studies have reported a role of radical forms of oxygen in the etiology of the manifestations of reperfusion of the ischemic myocardium. However, clinical results remain controversial. The aim of this study was to ascertain the existence of reperfusion-related radical stress after thrombolysis with a marker that is easy to use and reliable. Thirty patients hospitalized for acute myocardial infarction were involved in the study. Of these, 18 had been subjected to intravenous thrombolysis (Group I) and 12 had not (Group II). They were compared to two control groups who had no history of myocardial infarction. Of these, 16 were patients with coronary heart disease hospitalized for stable angina (Group III) and 17 were patients free of any known cardiovascular disease (Group IV). Radical activity was assessed in plasma samples taken from a peripheral vein over a 10-day period of hospitalization by measuring (1) malondialdehydes (MDA) concentrations using fluorometry techniques or HPLC, (2) the antioxidant activity of glutathione peroxidase (GPx) and (3) the concentration of various antiradical compounds (beta-carotene, vitamins A and E, uric acid). All patients in Group I had a patent artery on coronary angiography and showed a significant increase in plasma MDA when compared to those who had not been subjected to thrombolysis (3.15 +/- 0.62 and 2.70 +/- 0.40 mole/l of plasma, respectively). Furthermore, GPx plasma activity was also significantly increased following thrombolysis. By contrast, there was no significant alteration in the antiradical compounds measured. These data suggest that MDA measurements (an early measurement 1-2 days and a late measurement 5-7 days after reperfusion) by fluorometry is a good marker of radical stress during reperfusion in man. The assessment of this marker in patients might represent a simple and reliable test of reperfusion efficacy following thrombolysis, and it might enable one to test the effect of various antioxidant therapies associated with thrombolytic treatment.

N-acetylcysteine in combination with nitroglycerin and streptokinase for the treatment of evolving acute myocardial infarction. Safety and biochemical effects

BACKGROUND

N-acetylcysteine (NAC) has been shown to potentiate the effects of nitroglycerin (NTG) and to have antioxidant activity. This is the first study to assess the safety and effect of NAC in the treatment of evolving acute myocardial infarction (AMI).

METHODS AND RESULTS

Patients with AMI received either 15 g NAC infused over 24 hours (n = 20) or no NAC (n = 7), combined with intravenous NTG and streptokinase. Peripheral venous plasma malondialdehyde (MDA), reduced (GSH) and oxidized (GSSG) glutathione concentrations, and rate of reperfusion (using continuous ST-segment analysis) were measured. Cardiac catheterization was performed between days 2 and 5. No significant adverse events occurred. Less oxidative stress occurred in patients treated with NAC than in patients not receiving NAC (GSH to GSSG ratio 44 +/- 25 versus 19 +/- 13 at 4 hours, P < .05). NAC concentration (mean 172 +/- 79 mumol/L at 4 hours) was correlated to GSH concentration (P = .006). MDA concentrations were lower (P = .001) over the first 8 hours of treatment with NAC. There was a trend toward more rapid reperfusion (median 58 minutes, 95% confidence interval [CI] 48 to 98 minutes versus median 95 minutes, 95% CI 59 to 106 minutes; P = .17) and better preservation of left ventricular function (cardiac index 3.4 +/- 0.8 versus 2.6 +/- 0.27 L.min.m2, P = .009) with NAC treatment.

CONCLUSIONS

NAC in combination with NTG and streptokinase appeared to be safe for the treatment of evolving AMI and was associated with significantly less oxidative stress, a trend toward more rapid reperfusion, and better preservation of left ventricular function.

Lead-catalyzed peroxidation of essential unsaturated fatty acid

In the present study, the reaction mixtures (lead compounds with essential unsaturated fatty acids) were preincubated at 37 degrees C for 24 h prior to the measurement of malondialdehyde (MDA) by HPLC. The metal-catalyzed reactions were also compared in the presence of butylated hydroxytoluene (BHT), a free radical scavenger. Our results showed that according to the difference in the number of double bonds of essential unsaturated fatty acids, the kinds of lead compounds, and the concentrations of lead compounds, the extent of lipid peroxidation was different. The addition of BHT to the reaction mixtures significantly reduced the production of MDA (P < 0.01). These in vitro studies support prior in vivo reports that the important mechanism of the acute toxic effects of the lead compounds is owing at least in part, to metal-catalyzed peroxidation of polyunsaturated fatty acids.

Lipid peroxidation in workers exposed to lead

In animal studies, lead compounds increased lipid peroxidation. Using an industrial hygiene approach, we examined the hypothesis that whole blood lead concentration would be associated positively with lipid peroxidation in workers exposed to lead. Study subjects were 130 lead-exposed workers and controls from an industrial area in the south of Taiwan. Blood lead concentration was determined by atomic absorption spectrophotometry, and lipid peroxidation was determined by liquid chromatography. Lipid peroxidation was correlated weakly with blood lead when blood lead was less than 35 micrograms/dl, but it correlated strongly with blood lead when blood lead was greater than 35 micrograms/dl, especially when blood lead was greater than 40 micrograms/dl.

Pregnancy induced hypertension: a role for peroxidation in microvillus plasma membranes

It has been recently hypothesized that in PIH a placental oxidant-antioxidant imbalance might cause the release of lipoperoxidation products into the circulation, with subsequent damage of endothelial cell membranes. In this hypothesis the endothelial cell and further increase in circulating lipoperoxide levels, which are by themselves able to induce smooth muscle constriction and increased pressor responsiveness to angiotensin II. In order to investigate this issue, we studied the basal content of lipid peroxides in terms of malondialdehyde (MDA) in the syncytiotrophoblast plasma membranes (SPM) from PIH women. Moreover, we investigated the susceptibility to peroxidation of SPM using an in vitro oxidative stress as a tool to verify the predisposition to the in vivo development of peroxidation products. The fatty acid composition of the membranes was also analyzed. Microvillus membrane lipoperoxide concentrations were significantly increased in PIH women (62.8 +/- 7.6 ng MDA/mg prot) compared with healthy pregnant subjects (37.6 +/- 4.8 ng MDA/mg prot; p < 0.01). The formation of TBARS under the action of phenylhydrazine was significantly greater in PIH women (90.3 +/- 7.4 mmol MDA/mol cholesterol) than in normal pregnant subjects (68.6 +/- 6.4 mmol MDA/mol cholesterol; p < 0.01). In PIH microvillus membrane we also observed a significant increase of the content of polyunsaturated arachidonic acid. The increased susceptibility to oxidative stress of SPMs from PIH women might be due either to reduced antioxidant systems or to an abnormality of the lipid composition of the membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

Interferon decreases serum lipid peroxidation products of hepatitis C patients

Thiobarbituric acid reactive substances (TBARS) concentration in serum has been determined in healthy subjects and in patients suffering acute hepatitis and chronic cases of hepatitis C. Treatment with interferon of the chronic active hepatitis C patients, 5 x 10(6) U three times a week during 2 months, led in those patients whose SGPT activity normalized in serum, to a concomitant decrease in serum TBARS content. The possible theoretical involvement of peroxidation and antioxidants in this beneficial effect of interferon in hepatitis C patients is discussed. The results presented confirm the value of TBARS as laboratory test in the management of liver diseases and as a useful tool for the study of pathogenic and/or therapeutic mechanisms of this viral infection.

Human plasma lipid peroxide levels show a strong transient increase after successful revascularization operations

This study was performed to evaluate the hypothesis that oxygen radicals/lipid peroxidation are involved in reperfusion injury in humans. The study included 37 patients, who underwent surgical revascularization operations for kidney transplantation (9 subjects) or limb salvage (28 subjects). Peripheral venous blood samples were taken 30 min before starting reperfusion (baseline) and 1, 2, 3, 4, and occasionally 6 to 18 h after revascularization. The amount of plasma malonaldehyde formed in the reaction with thiobarbituric acid (MDA-TBA) was determined by high-performance liquid chromatography (HPLC). The baseline MDA-TBA values of the patients were very close to the value determined for 20 age-matched healthy subjects (i.e. mean +/- SD 0.689 +/- 0.294 nmol/mL plasma [range 0.2 to 1.37] vs. 0.700 +/- 0.209 nmol/mL plasma [range 0.385 to 1.29]). All patients responded to successful revascularization with significant increase of the plasma MDA-TBA within about 1 h after onset of reperfusion. Thereafter the values decreased nearly to the preoperative state. The mean increase of MDA-TBA was 107% in kidney transplantation and 54% in limb revascularization. In a few patients with severe arteriosclerosis, revascularization was not optimal and no increase in the MDA-TBA value occurred. The results of this study indicate that therapeutic intervention to prevent lipid-peroxidation-mediated reperfusion injury is confined to a rather narrow time window and must be undertaken either prior to or immediately after revascularization.

The role of lipid peroxidation and antioxidants in oxidative modification of LDL

The purpose of this study is to provide a comprehensive survey on the compositional properties of LDL (e.g., lipid classes, fatty acids, antioxidants) relevant for its susceptibility to oxidation, on the mechanism and kinetics of LDL oxidation, and on the chemical and physico-chemical properties of LDL oxidized by exposure to copper ions. Studies on the occurrence of oxidized LDL in plasma, arteries, and plaques of humans and experimental animals are discussed with particular focus on the use of poly- and monoclonal antibodies for immunochemical demonstration of apolipoprotein B modifications characteristic for lipid peroxidation. Apart from uptake of oxidized LDL by macrophages, studies describing biological effects of heavily or minimally oxidized LDL are only briefly addressed, since several reviews dealing with this subject were recently published. This article is concluded with a section on the role of natural and synthetic antioxidants in protecting LDL against oxidation, as well as some previously unpublished material from our laboratories.

Endothelial superoxide production in the isolated rat heart during early reperfusion after ischemia. A histochemical study

This paper describes a histochemical study of superoxide generation in buffer-perfused, isolated rat hearts during the first 2 minutes of reperfusion after 60 minutes of warm ischemia. Superoxide radical production was demonstrated by a modification of Karnovsky's manganese/diaminobenzidine technique, in which superoxide oxidizes Mn++ to Mn ions, which in turn oxidize diaminobenzidine to form amber, osmiophilic polymers, observable by light or electron microscopy. Isolated hearts were rendered ischemic, reperfused with oxygen equilibrated buffer containing Mn++ and diaminobenzidine, fixed by perfusion with Trump's solution, and processed for light and electron microscopy. The method consistently demonstrated evidence of superoxide generation near the luminal surfaces of arterial, capillary, and venular endothelial cells during the first 2 minutes of reoxygenation after ischemia. The histochemical reaction was absent or markedly reduced in non-manganese-treated or nonischemic hearts, as well as in hearts perfused with calcium-free or oxygen-free buffers. The histochemical differences were statistically significant on quantitative morphometric analysis. These results provide direct, visual evidence of the existence and endothelial localization of a burst of superoxide radicals in intact, postischemic myocardium and suggest the pathophysiologic importance of calcium-dependent endothelial cell activation in the initiation of reperfusion injury.

Radiochemical quantitation of conjugated dienes during ischemia and reperfusion in the rat liver

Conjugated dienes (CD) are putative chemical imprints of oxyradical damage. Employing a highly selective assay for dienes based on their condensation with 14C-tetracyanoethylene (14C-TCNE), and a 14C-TCNE reagent with 60 times higher specific radioactivity than that used by Waller and Recknagel (1978), we have described the profile of phospholipid CD during global ischemia and reperfusion of the rat liver. During 70 min of ischemia, the hepatic CD appeared to increase moderately, but not statistically significantly, relative to that in sham-operated controls (with mean CD = 0.0397 +/- 0.0040 nmoles CD/nmole phosphate, for n = 7). In subsequent reperfusion, CD increased 2.6-3.3 fold higher than in sham controls during the first 10-15 min, declining thereafter to ischemia-like levels by 30 min of reflow. Our data demonstrate that oxyradicals are generated mostly during reperfusion of the post-ischemic rat liver, and that the refined TCNE method can quantitate tissue CD sensitively and relatively specifically.

Chemistry and biochemistry of 4-hydroxynonenal, malonaldehyde and related aldehydes

Lipid peroxidation often occurs in response to oxidative stress, and a great diversity of aldehydes are formed when lipid hydroperoxides break down in biological systems. Some of these aldehydes are highly reactive and may be considered as second toxic messengers which disseminate and augment initial free radical events. The aldehydes most intensively studied so far are 4-hydroxynonenal, 4-hydroxyhexenal, and malonaldehyde. The purpose of this review is to provide a comprehensive summary on the chemical properties of these aldehydes, the mechanisms of their formation and their occurrence in biological systems and methods for their determination. We will also review the reactions of 4-hydroxyalkenals and malonaldehyde with biomolecules (amino acids, proteins, nucleic acid bases), their metabolism in isolated cells and excretion in whole animals, as well as the many types of biological activities described so far, including cytotoxicity, genotoxicity, chemotactic activity, and effects on cell proliferation and gene expression. Structurally related compounds, such as acrolein, crotonaldehyde, and other 2-alkenals are also briefly discussed, since they have some properties in common with 4-hydroxyalkenals.

Lipid peroxidation during myocardial ischaemia induced by pacing

Oxygen derived free radical generation can be shown in experimental models of myocardial ischaemia and reperfusion and may cause cellular damage by peroxidizing polyunsaturated membrane phospholipids. An attempt was made to quantify human intracardiac lipid peroxidation during transient myocardial ischaemia by measuring the aortic and coronary sinus concentrations of malondialdehyde (a marker of lipid peroxidation) before, during, and after incremental pacing. Twenty six patients were paced until they had severe chest pain or 2 mm ST segment depression or they reached a paced rate of 180 beats/min. They were divided into two groups according to whether or not lactate was produced during pacing. Twelve patients (group 1), all with coronary artery disease, produced myocardial lactate during pacing. None of the other 14 patients (group 2), half of whom had coronary disease, produced lactate during pacing. Concentrations of malondialdehyde in the aorta and coronary sinus were significantly higher in group 1 than in group 2. Five minutes after the end of pacing coronary sinus malondialdehyde concentrations in group 1 had increased significantly from baseline values. There were no changes with time in the coronary sinus concentration of malondialdehyde in group 2 or in the aorta in either group. The negative malondialdehyde extraction ratio in group 1 suggests that intracardiac lipid peroxidation occurs during transient human myocardial ischaemia.

A rapid, widely applicable screen for drugs that suppress free radical formation in ischemia/reperfusion

Substantial injury can occur during reoxygenation of previously ischemic tissue in many experimental models, as the result of the generation of oxygen-derived free radicals. To test the antiradical activity of potentially protective compounds in this setting, we developed a simple screening system, applicable to fresh biopsy specimens, in which warm ischemia and reoxygenation of excised tissue are performed in vitro. Tissue production of malondialdehyde (MDA) equivalents is used as a nonspecific-but-sensitive marker of oxygen radical damage. Test compounds with putative antiradical activity are added prior to the reoxygenation phase, and their ability to suppress MDA production is an index of activity in preventing reoxygenation injury. Comparison with ischemic but not reoxygenated controls confirms the oxygen-dependent nature of the effect. Standard positive controls of known effective agents, such as butylated hydroxytoluene or deferoxamine, provide a reference for the activity of the test compound. The method is applicable to surgical biopsy specimens in veterinary and human medicine.

Evaluation of an isoluminol chemiluminescence assay for the detection of hydroperoxides in human blood plasma

An assay for the separation and detection of lipid hydroperoxides and hydrogen peroxide in biological samples using HPLC and isoluminol chemiluminescence was recently described (Y. Yamamoto, M. H. Brodsky, J. C. Baker, and B. N. Ames (1987) Anal. Biochem. 160, 7-13; Y. Yamamoto and B. N. Ames (1987) Free Rad. Biol. Med. 3, 359-361). In this paper the application of this assay to the analysis of human blood plasma is described in detail, and three compounds producing chemiluminescence that were observed in the initial studies in plasma extracted with methanol and hexane are further characterized. It is shown that various lipid hydroperoxides added to plasma are detected by the assay. In contrast, hydrogen peroxide added to plasma is rapidly degraded by endogenous catalase. Hydrogen peroxide and a second, minor compound producing chemiluminescence, which appear in the assay of the methanol and the hexane extract of plasma, respectively, appear to be generated during analysis and are not likely to be present in plasma. The third compound yielding a chemiluminescence peak, which is extracted into the hexane phase of plasma and was earlier assigned to cholesterol ester hydroperoxide, is shown to be neither a cholesterol ester nor a hydroperoxide, but the hydroquinone ubiquinol-10. As the chemiluminescence response of hydroperoxides, but not of hydroquinones, is eliminated by reducing reagents such as sodium borohydride or triphenylphosphine, such reduction should be used to confirm that any chemiluminescence producing lipid observed in the assay is a hydroperoxide, not a hydroquinone. We conclude that isolated human plasma from healthy subjects is very unlikely to contain hydrogen peroxide in concentrations greater than about 0.25 microM and does not contain lipid hydroperoxides in concentrations greater than 0.03 microM. The method described, when used with appropriate precautions, is a convenient and very sensitive assay for lipid hydroperoxides in biological tissues.

Platelet derived malonyldialdehyde production in patients with thalassaemia major

Malonyldialdehyde, a product of membrane lipid peroxidation, was measured in the platelets of 16 normal subjects after stimulation with a variety of aggregating and stimulating agents. Nethylmaleimide and hydrogen peroxide generated the largest amounts of malonyldialdehyde. These agents were used to stimulate platelets from 11 patients with thalassaemia major suffering from iron overload due to repeated transfusion. Mean malonyldialdehyde concentrations were the same in normal subjects as in thalassaemic patients, but high concentrations were recorded in patients with severe iron overload. There was a highly significant correlation between malonyldialdehyde and serum ferritin concentrations in all thalassaemic patients. Platelet derived malonyldialdehyde may be a useful test of continuing membrane damage in patients with iron overload.