Measurement of serum lipid peroxidation during exercise using three different methods: diene conjugation, thiobarbituric acid reactive material and fluorescent chromolipids

Lipophilic fluorescent products as a potential biomarker of oxidative stress: A link between central (brain) and peripheral (blood)

Oxidative stress plays a key role in brain damage because of the sensitivity of brain tissue to oxidative damage. Biomarkers with easy measurement can be a candidate for reflecting the oxidative stress issue in humans. For this reason, we need to focus on specific metabolic products of the brain. End products of free radical reactions such as malondialdehydes form fluorescent products known as lipophilic fluorescent products (LFPs). The distinctive feature of LFPs is their autofluorescent properties. LFPs are detectable in the brain and cerebrospinal fluid. Furthermore, because of the diffusion into the bloodstream, these lipophilic molecules can be detected in the blood. Accumulations of these compounds produce more reactive oxygen species and increase the sensitivity of cells to oxidative damage. Hence, LFPs can be considered a danger signal for neurons and can be introduced as a strong index of oxidative damage both in the central and in the peripheral.

The Influence of Single Whole-Body Cryostimulation on Cytokine Status and Oxidative Stress Biomarkers during Exhaustive Physical Effort: A Crossover Study

The purpose of the study was to assess the impact of single whole-body cryostimulation (WBC) preceding submaximal exercise on oxidative stress and inflammatory biomarkers in professional, male athletes. The subjects (n = 32, age 25.2 ± 37) were exposed to low temperatures (−130 °C) in a cryochamber and then participated in 40 min of exercise (85% HRmax). Two weeks afterwards, the control exercise (without WBC) was performed. Blood samples were taken before the start of the study, immediately after the WBC procedure, after exercise preceded by WBC (WBC exercise) and after exercise without WBC. It has been shown that catalase activity after WBC exercise is lower in comparison with activity after control exercise. The interleukin 1β (IL-1-1β) level was higher after control exercise than after WBC exercise, after the WBC procedure and before the start of the study (p < 0.01). The WBC procedure interleukin 6 (IL-6) level was compared with the baseline level (p < 0.01). The level of Il-6 was higher both after WBC exercise and after control exercise compared with the level recorded after the WBC procedure (p < 0.05). Several significant correlations between the studied parameters were shown. In conclusion, the changes in the cytokine concentration in the athletes’ blood confirm that body exposition to extremely low temperatures before exercise could regulate the inflammatory reaction course and secretion of cytokines during exercise. A single session of WBC in the case of well-trained, male athletes does not significantly affect the level of oxidative stress indicators.

Interweaving of Reactive Oxygen Species and Major Neurological and Psychiatric Disorders

Reactive oxygen species are found to be having a wide range of biological effects ranging from regulating functions in normal physiology to alteration and damaging various processes and cell components causing a number of diseases. Mitochondria is an important organelle responsible for energy production and in many signalling mechanisms. The electron transport chain in mitochondria where oxidative phosphorylation takes place is also coupled with the generation of reactive oxygen species (ROS). Changes in normal homeostasis and overproduction of reactive oxygen species by various sources are found to be involved in multiple neurological and major neurodegenerative diseases. This review summarises the role of reactive oxygen species and the mechanism of neuronal loss in major neuronal disorders such as Alzheimer's disease, Parkinson's disease, Huntington's disease, Depression, and Schizophrenia.

Effects of ascorbic acid supplementation on oxidative stress markers in healthy women following a single bout of exercise

BACKGROUND

Ascorbic acid is a water-soluble chain breaking antioxidant. It scavenges free radicals and reactive oxygen species (ROS), which are produced during metabolic pathways. Exercise can produce an imbalance between ROS and antioxidants, leading to oxidative stress-related tissue damages. This study was designed to determine the effects of ascorbic acid supplementation on circulating biomarkers of oxidative stress and muscle damage following a single bout of exercise.

METHODS

In a crossover design with a 1 wk. wash-out period, 19 healthy women performed 30 min moderate-intensity cycling after ingesting 1000 mg of ascorbic acid (AA) or placebo. Blood samples were taken immediately before, immediately after and 30 min post-exercise to determine plasma albumin, total protein, glucose, oxidative stress and muscle damage markers.

RESULTS

Plasma albumin and total protein levels increased immediately after exercise in placebo alongside slight reductions in glucose (p = 0.001). These effects were absent in AA cohort. Ferric reducing ability of plasma and vitamin C levels in AA cohort significantly increased after exercise (p < 0.05). Superoxide dismutase activity was significantly elevated after exercise (p = 0.002) in placebo but not AA. Plasma malondialdehyde did not change after exercise in placebo but was significantly decreased in AA (p < 0.05). The exercise protocol promoted slight muscle damage, reflected in significant increases in total creatine kinase in all subjects after exercise. On the other hand, plasma C-reactive protein and lactate dehydrogenase remained unchanged.

CONCLUSION

Supplementation with ascorbic acid prior exercise improves antioxidant power but does not prevent muscle damage.

The Oxidant-Antioxidant Equilibrium and Inflammatory Process Indicators after an Exercise Test on the AlterG Antigravity Treadmill in Young Amateur Female Athletes

The AlterG antigravity treadmill allows running with a considerable weight reduction. Physical exercise practiced on this treadmill is an innovative method supporting the treatment of injuries in sports and rehabilitation of patients. The aim of the study was to investigate the effect of a 30 min run on the AlterG treadmill with 80% body weight reduction comparing the effect to the similar effort on the classic treadmill on the redox equilibrium and the activity of selected lysosomal enzymes and a serine protease inhibitor in the blood of amateur minor female volleyball players. Venous blood samples were taken before the exercise and 30 minutes and 24 hours after its completion. The obtained results were analysed using Tukey's test and Pearson's linear correlations were calculated. 24 h after the running test on classic treadmill, the erythrocytic superoxide dismutase activity was higher than before and 30 min after it, as well as compared to the run on AlterG treadmill (p < 0.001). The erythrocytic-conjugated diene concentration 24 h after the exercise on the classic treadmill was meaningly higher compared to that after the exercise on the AlterG treadmill (p < 0.001). The cathepsin D activity was significantly lower after the exercise in AlterG conditions compared to the baseline value and that measured after the exercise on classic treadmill (p < 0.001). It seems that the exercise on the AlterG treadmill keeps the oxidant–antioxidant equilibrium and stabilizes lysosomal membranes in young, physically active women in contrast to the exercise on the classic treadmill. This trial is registered with CTRI/2018/01/011344.

Changes of oxidative/antioxidative parameters and DNA damage in firefighters wearing personal protective equipment during treadmill walking training

[Purpose] The purpose of this study was to investigate the influence of personal protective equipment on the oxidant/antioxidant parameters and DNA damage in firefighters during training and recovery. [Subjects and Methods] Twelve male nonsmoking volunteer firefighters (35.1 ± 7.2 years) underwent two maximal treadmill training (9 METs, 6 km/h), within 2 weeks, one in regular clothes and one in personal protective equipment weighing 22.1 kg. Blood samples were obtained before, right after, and 40 min after training. Plasma conjugated dienes, total radical trapping antioxidant potential, erythrocytes antioxidant enzymes activities, and leukocyte DNA damage were measured. [Results] Wearing personal protective equipment during treadmill walking training resulted in increases of plasma conjugated dienes, total radical trapping antioxidant potential, and leukocyte DNA resistance to oxidative stress, which were recovered after in 40 min of rest. Erythrocyte antioxidant enzymes activities remained unchanged during the training either with regular clothes or personal protective equipment. [Conclusion] These results suggest that wearing personal protective equipment during firefighting work could induce oxidative stress, which was enough to produce DNA damage in leukocytes.

Relationship of classical and non-classical risk factors with genetic variants relevant to coronary heart disease

BACKGROUND

In addition to the well established cardiovascular risk factors, evidence suggests a possible role of genetic and non-classical risk factors in the development and progression of atherothrombosis. We aimed to determine the relationship of classical and non-classical cardiovascular risk factors with candidate gene polymorphisms potentially involved in cardiovascular risk in the general Mediterranean population.

DESIGN

Cross-sectional study.

METHODS

We have determined the prevalence of classical (lipid profile, blood pressure, glycaemia, diabetes, smoking, body mass index, menopause and family history of coronary heart disease) and non-classical cardiovascular risk factors (infectious processes, homocysteinaemia, oxidative status, C-reactive protein, lipoprotein (a) and fibrinogen) in a population-based study. We analysed the relationship of these risk factors with the following five gene polymorphisms potentially involved in cardiovascular risk: ATP-binding cassette transporter A1-R219K, Peroxisome proliferator-activated receptor (PPAR)-alpha-L162V, Lipoprotein lipase (LPL)-HindIII, Paraoxonase (PON)1-Q192R, and Tumour necrosis factor (TNF)-alpha-G-308A.

RESULTS

We found PPAR-alpha-V and LPL-H alleles to be associated with decreased high-density lipoprotein-cholesterol (HDL-c) concentration and with increased total cholesterol : HDL-c and triglyceride : HDL-c ratios. Regarding the non-classical risk factors, C-reactive protein concentration was higher for the PPAR-alpha-V allele. A higher oxidative status was shown in homozygotes for LPL-H and TNF-alpha-G alleles, although the latter also had lower homocysteinaemia.

CONCLUSIONS

Three of the genetic variants analysed, PPAR-alpha-L162V, LPL-HindIII, and TNF-alpha-G-308A, were associated with non-classical risk factors, specifically lipid profile, inflammation, and oxidative status.

Changes in the Composition of Fatty Acids and Lipofuscin-Like Pigments During Development of Rat Heart

Postnatal heart development is characterized by critical periods of heart remodeling. In order to characterize the changes in the lipophilic fraction induced by free radicals, fatty acids and their oxidized products, lipofuscin-like pigments (LFP), were investigated. Fatty acids were analyzed by gas chromatography and LFP were studied by fluorescence techniques. A fluorophore characterized by spectral methods was further resolved by HPLC. Major changes in the composition of fatty acids occurred immediately after birth and then during maturation. Fluorescence of LFP changed markedly on postnatal days 1, 4, 8, and 14, and differed from the adult animals. LFP comprise several fluorophores that were present since fetal state till adulthood. No new major fluorophores were formed during development, just the abundances of individual fluorophores have been modulated which produced changes in the shape of the spectral arrays. HPLC resolved the fluorophore with excitation maximum at 360 nm and emission maximum at 410 nm. New chromatographically distinct species appeared immediately on postnatal day 1, and then on days 30 and 60. Consumption of polyunsaturated fatty acids immediately after birth and subsequent formation of LFP suggests that oxidative stress is involved in normal heart development.

Alterations in redox homeostasis in the elite endurance athlete

BACKGROUND

The production of reactive oxygen (ROS) and nitrogen species (RNS) is a fundamental feature of mammalian physiology, cellular respiration and cell signalling, and essential for muscle function and training adaptation. Aerobic and anaerobic exercise results in alterations in redox homeostasis (ARH) in untrained, trained and well trained athletes. Low to moderate doses of ROS and RNS play a role in muscle adaptation to endurance training, but an overwhelming increase in RNS and ROS may lead to increased cell apoptosis and immunosuppression, fatigued states and underperformance.

OBJECTIVES

The objectives of this systematic review are: (a) to test the hypotheses that ARH occur in elite endurance athletes; following an acute exercise bout, in an endurance race or competition; across a micro-, meso- or macro-training cycle; following a training taper; before, during and after altitude training; in females with amenorrhoea versus eumenorrhoea; and in non-functional over-reaching (NFOR) and overtraining states (OTS); (b) to report any relationship between ARH and training load and ARH and performance; and (c) to apply critical difference values for measures of oxidative stress/ARH to address whether there is any evidence of ARH being of physiological significance (not just statistical) and thus relevant to health and performance in the elite athlete.

METHODS

Electronic databases, Embase, MEDLINE, and SPORTDiscus were searched for relevant articles. Only studies that were observational articles of cross-sectional or longitudinal design, and included elite athletes competing at national or international level in endurance sports were included. Studies had to include biomarkers of ARH; oxidative damage, antioxidant enzymes, antioxidant capacity, and antioxidant vitamins and nutrients in urine, serum, plasma, whole blood, red blood cells (RBCs) and white blood cells (WBCs). A total of 3,057 articles were identified from the electronic searches. Twenty-eight articles met the inclusion criteria and were included in the review.

RESULTS

ARH occurs in elite endurance athletes, after acute exercise, a competition or race, across training phases, and with natural or simulated altitude. A reduction in ARH occurs across the season in elite athletes, with marked variation around intensified training phases, between individuals, and the greatest disturbances (of physiological significance) occurring with live-high-train-low techniques, and in athletes competing. A relationship with ARH and performance and illness exists in elite athletes. There was considerable heterogeneity across the studies for the biomarkers and assays used; the sport; the blood sampling time points; and the phase in the annual training cycle and thus baseline athlete fitness. In addition, there was a consistent lack of reporting of the analytical variability of the assays used to assess ARH.

CONCLUSIONS

The reported biochemical changes around ARH in elite athletes suggest that it may be of value to monitor biomarkers of ARH at rest, pre- and post-simulated performance tests, and before and after training micro- and meso-cycles, and altitude camps, to identify individual tolerance to training loads, potentially allowing the prevention of non-functionally over-reached states and optimisation of the individual training taper and training programme.

Role of nitric oxide and related molecules in schizophrenia pathogenesis: biochemical, genetic and clinical aspects

Currently, schizophrenia is considered a multifactorial disease. Over the past 50 years, many investigators have considered the role of toxic free radicals in the etiology of schizophrenia. This is an area of active research which is still evolving. Here, we review the recent data and current concepts on the roles of nitric oxide (NO) and related molecules in the pathogenesis of schizophrenia. NO is involved in storage, uptake and release of mediators and neurotransmitters, including glutamate, acetylcholine, noradrenaline, GABA, taurine and glycine. In addition, NO diffuses across cell membranes and activates its own extrasynaptic receptors. Further, NO is involved in peroxidation and reactive oxidative stress. Investigations reveal significant disturbances in NO levels in the brain structures (cerebellum, hypothalamus, hippocampus, striatum) and fluids of subjects with schizophrenia. Given the roles of NO in central nervous system development, these changes may result in neurodevelopmental changes associated with schizophrenia. We describe here the recent literature on NOS gene polymorphisms on schizophrenia, which all point to consistent results. We also discuss how NO may be a new target for the therapy of mental disorders. Currently there have been 2 randomized double-blind placebo-controlled trials of L-lysine as an NOS inhibitor in the CNS.

Impact of oxidative stress on exercising skeletal muscle

It is well established that muscle contractions during exercise lead to elevated levels of reactive oxygen species (ROS) in skeletal muscle. These highly reactive molecules have many deleterious effects, such as a reduction of force generation and increased muscle atrophy. Since the discovery of exercise-induced oxidative stress several decades ago, evidence has accumulated that ROS produced during exercise also have positive effects by influencing cellular processes that lead to increased expression of antioxidants. These molecules are particularly elevated in regularly exercising muscle to prevent the negative effects of ROS by neutralizing the free radicals. In addition, ROS also seem to be involved in the exercise-induced adaptation of the muscle phenotype. This review provides an overview of the evidences to date on the effects of ROS in exercising muscle. These aspects include the sources of ROS, their positive and negative cellular effects, the role of antioxidants, and the present evidence on ROS-dependent adaptations of muscle cells in response to physical exercise.

Cytotoxic effects on tumour cell lines of fatty acids from the marine sponge Scopalina ruetzleri

OBJECTIVES

Marine sponges are among the most promising sources of chemically diversified fatty acids (FAs). In addition, several studies have shown the effect of polyunsaturated FAs on cancer therapy. This research carried out a biological and chemical evaluation of the sponge Scopalina ruetzleri collected on the South Brazilian coastline.

METHODS

Bioassay-guided fractionation of S. ruetzleri was performed in human glioma (U87) and neuroblastoma (SH-SY5Y) cell lines, and the in-vitro effects on free radicals were evaluated.

KEY FINDINGS

The ethyl acetate fraction of S. ruetzleri showed promising cytotoxic effects in cancer cell lines, with IC50  < 20 μg/ml. Fingerprint (1) H Nuclear Magnetic Resonance (NMR) analysis showed that this fraction is mainly constituted of FAs. Through FA methyl ester analysis, it was possible to identify 32 FAs. In addition, some minor unusual FAs for the marine biosphere were identified. The results of conjugated dienes method showed that FAs fraction, at concentrations above 50 μg/ml, has a pro-oxidant effect, indicating that lipid peroxidation may be partially responsible for the mechanism of cytotoxicity on cancer cells.

CONCLUSION

This work also contributes to studies that focus on the application of FAs on cancer therapy as a new adjuvant to radio or chemotherapy, or as a chemotherapeutic agent.

Ontogenetic changes of lipofuscin-like pigments in the rat heart

Increased generation of reactive oxygen species results in the formation of fluorescent end-products of lipid peroxidation - lipofuscin-like pigments (LFP). LFP increased up to six-fold from the fetal value in the rat heart immediately after birth. In the experimental design of this study the fetuses were sampled 1 day before birth, and then the samples were collected on postnatal days 1, 4, 7, 10, 15, 30, and 60. Males and females were compared on day 30 and 60 when the difference between right and left ventricle was studied as well. Four LFP fluorophores were analyzed: F355/440, F310/470, F350/450, F315/450 (excitation/emission, nm). All fluorophores decreased on day 4 relative to day 1, subsequent transient increases ended in a significant decrease on day 60. However, the LFP levels on day 60 are still about threefold higher than those in fetuses. Differences between male and female hearts were observed on day 30. The corresponding male ventricles contained by one third higher concentration of LFP than the female counterparts. The increase in LFP concentration in male ventricles on day 30 was only transient, no difference between corresponding male and female ventricles was found on day 60. The most distinguished feature in the male heart was a sharp LFP decrease in the right ventricle on day 60.

Eight weeks of conjugated linoleic acid supplementation has no effect on antioxidant status in healthy overweight/obese Korean individuals

PURPOSE

The aim of this study was to evaluate the effect of CLA supplementation on antioxidant metabolism in healthy overweight/obese Korean individuals.

METHODS

We performed a randomized, double-blind, placebo-controlled trial, where 29 healthy overweight/obese (BMI ≥ 23 kg/m(2)) participants (2 men and 27 women) were randomly selected to receive placebo (n = 15, 2.4 g olive oil/day) or 2.4 g/day CLA mixture (n = 14, 36.9% of cis-9, trans-11 and 37.9% of trans-10, cis-12) for 8 weeks.

RESULTS

There were no significant differences in plasma total radical-trapping antioxidant potential (TRAP), lipid peroxidation (conjugated dienes), lipid-soluble antioxidant vitamin concentration, erythrocyte antioxidant enzyme (superoxide dismutase, catalase, glutathione peroxidase) activities, and leukocyte DNA damage between the CLA and placebo groups.

CONCLUSIONS

The data suggest that short-term supplementation (8 weeks) with CLA (2.4 g/day) might have no significant effects on lipid peroxidation and antioxidant metabolism.

Early postnatal development of rat brain is accompanied by generation of lipofuscin-like pigments

The increased generation of free radicals results in the formation of fluorescent end-products of lipid peroxidation, lipofuscin-like pigments (LFPs). The authors observed that LFPs are generated in rat brain after a normal birth during 5 postnatal days. The experimental design of the study comprised 10 groups of animals. The authors measured prenatal values 1 day and 7 days before birth, and then the animals were sampled on postnatal day 1, 2, 5, 10, 15, 25, 35, and 90. Maximum LFP concentration is achieved on the postnatal day 2. Starting from postnatal day 10, LFP concentration returns to prenatal values. A new rise in LFP concentration is observed at 3 months of age. This is associated with the beginning of the aging process. LFPs were characterized by fluorescence spectroscopy using tridimensional excitation spectra, synchronous spectra and their derivatives, and HPLC with fluorescence detection. It was possible to discern several tens of fluorescent compounds of unknown structure that are generated and metabolized during early development. The authors suggest that LFPs are formed after respiratory burst of microglia phagocytosing apoptotic cells.

Effect of ozone/oxygen mixture on systemic oxidative stress and organic damage

Ozone is a molecule of high energetic content. Its great oxidative power has been used in medicine for the treatment of several illnesses with a wide spectrum. The rectal insufflation with a mixture of ozone/oxygen is considered as a simple therapy, not painful, of low cost and practically free from adverse effects. Given its potential oxidation and lack of side-effects, the objective has been to know the state of different indexes of redox state in blood which may contribute to understanding the mechanism by which mixtures of ozone/oxygen administered by intrarectal route are able to exert actions on other organs. With this purpose female rabbits were used, distributed into four groups, and three doses of ozone/oxygen mixture were tested. When treatment was finished, the determination of pro-oxidant and antioxidant markers was carried out. Also indexes of organic damage were determined. Ozone doses administered to rabbits did not cause adverse effects and mortality did not show significant changes relative to tissue damages and they increased enzymes activities belonging to the first line antioxidant defences. The results demonstrate that ozone/oxygen mixture administered by rectal insufflations is innocuous and it is able to increase the antioxidant defense of the organism.

Local and systemic oxidant/antioxidant status before and during lung cancer radiotherapy

To examine local and systemic oxidative status of lung cancer (LC) and oxidant effects of radiotherapy (RT), this study evaluated antioxidants and markers of oxidative and nitrosative stress in bronchoalveolar lavage (BAL) fluid and in the blood of 36 LC patients and 36 non-cancer controls at baseline and during and after RT for LC. LC patients had higher baseline serum urate, plasma nitrite and lower serum oxidized proteins than controls (p = 0.016, p < 0.001 and p = 0.027, respectively), but BAL fluid oxidative stress markers were similar. RT tended to raise some antioxidants, however, significant increases were seen in serum urate, conjugated dienes and TBARS (p = 0.044, p = 0.034 and p = 0.004, respectively) 3 months after RT. High urate at baseline may compensate against the oxidative stress caused by LC. RT shifts the oxidant/antioxidant balance towards lipid peroxidation, although the antioxidant defense mechanisms of the body appear to counteract the increased oxidative stress rather effectively.

Exhaled pentane as a possible marker for survival and lipid peroxidation during radiotherapy for lung cancer--a pilot study

To examine lipid peroxidation during radiotherapy (RT), exhaled pentane samples were collected from 11 lung cancer patients before RT and 30 and 120 min after the start of RT on days 1, 4 and 5 and at 30 and 40 Grays, if possible. Exhaled pentane samples were collected once from 30 healthy controls. Serum thiobarbituric-acid-reactive substances (TBARS) and conjugated dienes (CD) were obtained from patients on each exhaled air collection day. Lung cancer patients had higher exhaled pentane levels than controls (1.73 ng/L vs 0.83 ng/L, p=0.017). Exhaled pentane levels tended to decrease during the first RT day (p=0.075) and levels of CD decreased during the first week of RT (p=0.014). Higher pre-treatment pentane levels predicted better survival (p=0.003). Elevated exhaled pentane levels before RT may be due to the lipid peroxidation burden associated with cancer. The decrease of lipid peroxidation markers during RT may be attributable to enhanced antioxidant defense mechanisms.

Concurrent decline of several antioxidants and markers of oxidative stress during combination chemotherapy for small cell lung cancer

OBJECTIVES

To investigate the oxidant effects of adriamycin-containing chemotherapy (CT), we evaluated various antioxidants, total antioxidant capacity (TRAP) and different parameters of oxidative and nitrosative stress during combination CT.

DESIGN AND METHODS

Blood samples were obtained from 16 small cell lung cancer patients at baseline and several times during the first, second and sixth CT cycles.

RESULTS

There were significant decreases in serum urate and serum proteins during all cycles, serum TRAP during the first two cycles, plasma ascorbic acid and serum TBARS during the first cycle, and serum conjugated dienes and plasma alphatocopherol during the last cycle. The baseline levels of tocopherols increased significantly between the first and sixth CT cycles. Higher levels of baseline plasma thiols were associated with better overall survival (p=0.008).

CONCLUSIONS

Adriamycin-containing CT causes significant oxidative stress as implied by reduced levels of protective antioxidants. Long-term CT treatment seems to enhance lipid peroxidation.

Acute exercise and oxidative stress: a 30 year history

The topic of exercise-induced oxidative stress has received considerable attention in recent years, with close to 300 original investigations published since the early work of Dillard and colleagues in 1978. Single bouts of aerobic and anaerobic exercise can induce an acute state of oxidative stress. This is indicated by an increased presence of oxidized molecules in a variety of tissues. Exercise mode, intensity, and duration, as well as the subject population tested, all can impact the extent of oxidation. Moreover, the use of antioxidant supplements can impact the findings. Although a single bout of exercise often leads to an acute oxidative stress, in accordance with the principle of hormesis, such an increase appears necessary to allow for an up-regulation in endogenous antioxidant defenses. This review presents a comprehensive summary of original investigations focused on exercise-induced oxidative stress. This should provide the reader with a well-documented account of the research done within this area of science over the past 30 years.

To What Extent Does Ozone Therapy Need a Real Biochemical Control System? Assessment and Importance of Oxidative Stress

Ozone therapy is not officially allowed in many countries, but private medical services are using this therapy worldwide. However, appropriate control systems to assess the benefits and risks of systemic ozone therapy are not always used and in such cases the treatment is based on anecdotal reports. Oxidative stress phenomenon is becoming a highlighted biological process for ozone therapy because it is deeply involved in its mechanism of action. On the contrary, ozone therapy is an efficient regulator of the oxidative stress processes. In terms of therapeutic effects, it is convenient to know the metabolic status of the organism to face new oxidative challenges before and during ozone therapy applications. Oxidative stress is also important because it is involved as a cause or effect of many diseases. Since the 1990s, there has been the necessity of developing reliable systems for measuring oxidative stress in humans. In this sense, we have proposed a system for oxidative stress diagnosis that can serve as a control system for systemic ozone therapy applications. The system is based on the blood measurement of eight biomarkers (GSH, GPx, GST, SOD, CAT, DC, SRATB, and HPT) and the interpretation of these values by a computer-developed algorithm yielding four new indices (total antioxidant activity, total prooxidant activity, redox index and grade of oxidative stress). The system shows the patient's redox status and estimation of the oxidative stress level, with this information being relevant regarding implications on dosage and therapeutic effectiveness of ozone therapy.

Plasma Levels of Leptin Are Associated with the Plasma Levels of LDL Conjugated Dienes in Children

BACKGROUND

Plasma leptin has been suggested to be involved in the proatherogenic process by increasing oxidative stress. We investigated the relationship between leptin and plasma conjugated diene formation, a measure of LDL oxidation in vivo in schoolchildren.

METHODS

We measured blood lipid profiles, plasma antioxidant vitamins, leptin and diene conjugation in LDL of 118 Korean children (35 overweight-obese vs. 83 normal weight children).

RESULTS

The overweight-obese children showed significantly higher levels of leptin (p < 0.0001), conjugated dienes (p = 0.02), total cholesterol (p < 0.05), triglyceride (p < 0.005) and LDL cholesterol (p < 0.01) and a significantly lower level of plasma lycopene (p < 0.0001) compared with the normal weight children. When all the subjects were classified into the three groups by tertiles of leptin levels, significant differences in circulating conjugated dienes (p < 0.05), lipid-corrected lycopene (p < 0.05), total cholesterol (p < 0.05), triglyceride (p < 0.05) and LDL cholesterol (p < 0.05) were found among the three groups.

CONCLUSION

Our results showed that leptin was positively associated with the LDL conjugated diene formation, which might be related to the proatherogenic process in schoolchildren.

Effects of iron overload in a rat nutritional model of non-alcoholic fatty liver disease

BACKGROUND/AIMS

This study sought to determine whether excess hepatic iron potentiates liver injury in the methionine choline-deficient (MCD) model of non-alcoholic fatty liver disease (NAFLD).

METHODS

Iron-loaded rats were fed either MCD or control diets [MCD diet plus choline bitartrate (2 g/kg) and DL-methionine (3 g/kg)] for 4 and 12 weeks, after which liver pathology, hepatic iron, triglyceride, lipid peroxidation products and hydroxyproline (HYP) levels and serum alanine aminotransferase (ALT) levels were evaluated.

RESULTS

Iron supplementation in MCD animals resulted in histologic evidence of hepatic iron overload at 4 and 12 weeks and a 14-fold increase in hepatic iron concentration at 12 weeks (P < 0.001). Iron supplementation in these animals was associated with increased lobular necroinflammation at 4 weeks (P < 0.02) and decreased hepatic steatosis (P < 0.01), hepatic triglyceride levels (P < 0.01), hepatic-conjugated dienes (CD; P < 0.02) and serum ALT levels (P < 0.002) at 12 weeks. Reduced hepatic steatosis (P < 0.005) and CD (P < 0.01) were apparent by 4 weeks. Iron supplementation was associated with a trend towards increased perivenular fibrosis not hepatic HYP content.

CONCLUSION

Hepatic iron overload in the MCD model of NAFLD is associated with decreased hepatic lipid, decreased early lipid peroxidation products, increased necroinflammation and a trend towards increased perivenular fibrosis.

Silybin reduces lipid peroxidation of rat hepatocyte membrane caused by cyclosporin A

An effect of cyclosporin A on lipid peroxidation in isolated rat hepatocytes was tested. A significant increase in lipid peroxidation marker (the concentration of lipofuscin-like pigments) was observed in samples incubated with cyclosporin A in comparison with the control. When hepatoprotective flavonoid silybin was added, the production of lipofuscin-like pigments decreased significantly. This result indicates a potential positive role of silybin in lowering of cyclosporin A side effects associated with the production of reactive oxygen species and plasma membrane damage.

Exercise-induced oxidative stress:myths, realities and physiological relevance

Although assays for the most popular markers of exercise-induced oxidative stress may experience methodological flaws, there is sufficient credible evidence to suggest that exercise is accompanied by an increased generation of free radicals, resulting in a measurable degree of oxidative modifications to various molecules. However, the mechanisms responsible are unclear. A common assumption that increased mitochondrial oxygen consumption leads per se to increased reactive oxygen species (ROS) production is not supported by in vitro and in vivo data. The specific contributions of other systems (xanthine oxidase, inflammation, haem protein auto-oxidation) are poorly characterised. It has been demonstrated that ROS have the capacity to contribute to the development of muscle fatigue in situ, but there is still a lack of convincing direct evidence that ROS impair exercise performance in vivo in humans. It remains unclear whether exercise-induced oxidative modifications have little significance, induce harmful oxidative damage, or are an integral part of redox regulation. It is clear that ROS play important roles in numerous physiological processes at rest; however, the detailed physiological functions of ROS in exercise remain to be elucidated.

The clinical significance of cerebrospinal fluid lipid peroxides in central nervous system disease

Forty-four dogs were referred to our hospital presenting with neurological symptoms such as seizure or paraparesis. Magnetic resonance imaging (MRI) revealed abnormal results in 21 (abnormal MRI group) and normal results in 23 dogs (normal MRI group). Cerebrospinal fluid (CSF) (normal MRI group, n = 22; abnormal MRI group, n = 21) and serum lipid peroxide (LP) concentrations (normal MRI group, n = 11; abnormal MRI group, n = 15) were measured in a number of these dogs, and revealed a significant difference in the CSF/serum LP values (normal MRI group, n = 10; abnormal MRI group, n = 14) between the abnormal and the normal MRI groups (t-test and Mann-Whitney U-test p < 0.05). No other significant differences were observed. CSF/serum LP values exceeding 1.0 were exhibited in 10 of 14 dogs (71%) in the abnormal MRI group, and in 1 of 10 dogs (10%) in the normal MRI group. In the remaining animals, 4 dogs of the abnormal MRI group showed CSF/serum values lower than 1.0, 3 dogs had morphological abnormalities but no abnormal MRI signals in the central nervous system, and 1 dog had an abnormal MRI signal but no pathological abnormality. In the CSF analysis, 3 of 16 dogs (19%) of the abnormal MRI groupshowed abnormal cell counts and/or protein content. We conclude that the CSF/serum LP value can be used for the detection of neurological lesions such as oedema, inflammation and tumour.

Rodent nutritional model of steatohepatitis: effects of endotoxin (lipopolysaccharide) and tumor necrosis factor alpha deficiency

BACKGROUND AND AIMS

Intestinal endotoxin (lipopolysaccharide) is thought to contribute to liver injury in both alcoholic and nonalcoholic steatohepatitis (NASH). Tumor necrosis factor alpha (TNFalpha) is an important mediator of this process and is considered central to the inflammatory response in NASH. This study aimed to investigate the effects of lipopolysaccharide on liver injury in the methionine choline deficient (MCD) nutritional model of NASH, and to determine if TNFalpha is required for the development of steatohepatitis in this model.

METHOD

Male C57/BL6 mice received a MCD diet for 4 weeks, whilst a control group received an identical diet supplemented with 0.2% choline bitartrate and 0.3% methionine. At 4 weeks, mice received either an intraperitoneal injection of lipopolysaccharide (0.5 microg/g body mass) or sterile saline, and were killed 24 h thereafter. In a separate study, TNFalpha knockout and wild type C57BL/6 mice received either MCD or control diets for 4 weeks. Serum transaminase levels, liver histology (steatosis, inflammation and apoptosis), hepatic triglyceride concentration and hepatic lipid peroxidation products (conjugated dienes, lipid hydroperoxides and thiobarbituric reactive substances, free and total) were evaluated.

RESULTS

Intraperitoneal administration of lipopolysaccharide augmented serum alanine aminotransferase (ALT) levels (P<0.02), hepatic inflammation (P<0.025), apoptosis (P<0.01) and free thiobarbituric acid reactive substances (P<0.025) in MCD mice. TNFalpha knockout mice fed the MCD diet developed steatohepatitis with histological and biochemical changes similar to those seen in wild type counterparts.

CONCLUSIONS

Lipopolysaccharide augments liver injury in MCD mice, and TNFalpha is not required for the development of steatohepatitis in MCD mice.

N-acetylcysteine as an additive to crystalloid cardioplegia increased oxidative stress capacity in CABG patients

OBJECTIVE

This prospective, randomized study was designed to assess the effects of N-acetylcysteine (NAC) in coronary artery bypass graft (CABG) patients.

DESIGN

Thirty-five consenting CABG patients with normal myocardial function were randomly divided into control (C) patients (N = 20) who received crystalloid (Plegisol) cardioplegia, and NAC patients receiving NAC in a 0.04 mol/l solution (N = 15) in Plegisol. Simultaneous coronary sinus and aortic blood samples, and myocardial biopsies were taken 1, 5 and 10 min after declamping. Hemodynamics was measured invasively for 24 h.

RESULTS

There were no adverse effects observed. The myocardial glutathione content was significantly better preserved (p = 0.0001) and myeloperoxidase activity was over two times lower in the NAC group than in the C group (p = 0.03). The trap capacity gradient between the aorta and the coronary sinus increased significantly during the first minute of reperfusion in the treatment group (p = 0.001) when compared with the C group. In the first minute after reperfusion there were more leukocytes sequestered in the coronary circulation (p = 0.04) in the C group. The invasive hemodynamic data did not differ significantly between the groups. The incidence of arrhythmias was equal.

CONCLUSION

NAC increased tissue capacity against oxidative stress and decreased inflammatory response in CABG patients with normal ejection fraction.

The effects of antioxidants on exercise-induced lipid peroxidation in patients with COPD

OBJECTIVE

The oxidant-antioxidant balance plays an important role in the pathogenesis of COPD. The aim of the present study was to evaluate the effects of exercise, as an oxidative stress factor on the oxidant-antioxidant balance and to investigate whether short-term antioxidant treatment affects lipid peroxidation products.

METHODOLOGY

Twenty-one stable COPD patients and 10 control subjects were included in the study. Symptom-limited exercise tests were performed by all subjects. Blood was collected before and 1 h after exercise in control subjects and before, 1 and 3 h after exercise in COPD patients, for analysis of malondialdehyde (MDA), reduced glutathione (GSH) and vitamin E (VE) levels. VE and vitamin C treatments were added to the regular bronchodilator therapy in 10 COPD patients for 1 month. After the treatment period, an exercise test was performed and blood was collected again for MDA, GSH and VE levels.

RESULTS

Baseline GSH and VE levels were significantly lower in the COPD group when compared with the control subjects. There was no statistically significant difference in MDA levels between the two groups. In the COPD group, MDA levels 3 h after exercise were significantly higher than at baseline. In contrast there were no significant differences in MDA, VE and GSH levels in the control group after exercise. VE and MDA levels increased significantly after exercise in COPD patients but there was no difference in GSH levels. Baseline exercise time was significantly lower in the COPD group than in the controls. In 10 COPD patients who were given antioxidant therapy, their exercise time increased significantly and there was no increase in MDA and VE levels after the repeated exercise test.

CONCLUSIONS

Antioxidant levels were significantly lower in COPD patients than in control subjects. In these patients, exercise results in more significant oxidative stress and lipid peroxidation than in control subjects and antioxidant therapy may decrease lipid peroxidation following exercise and improve exercise capacity.

Arterial desaturation during exercise in man: implication for O2 uptake and work capacity

Exercise-induced arterial hypoxaemia is defined as a reduction in the arterial O2 pressure (PaO2) by more than 1 kPa and/or a haemoglobin O2 saturation (SaO2) below 95%. With blood gas analyses ideally reported at the actual body temperature, desaturation is a consistent finding during maximal ergometer rowing. Arterial desaturation is most pronounced at the end of a maximal exercise bout, whereas the reduction in PaO2 is established from the onset of exercise. Exercise-induced arterial hypoxaemia is multifactorial. The ability to maintain a high alveolar O2 pressure (PAO2) is critical for blood oxygenation and this appears to be difficult in large individuals. A large lung capacity and, in turn, diffusion capacity seem to protect PaO2. A widening of the PAO2-PaO2 difference does indicate that a diffusion limitation, a ventilation-perfusion mismatch and/or a shunt influence the transport of O2 from alveoli to the pulmonary capillaries. An inspired O2 fraction of 0.30 reduces the widened PAO2-PaO2 difference by 75% and prevents a reduction of PaO2 and SaO2. With a marked increase in cardiac output, diffusion limitation combined with a fast transit time dominates the O2 transport problem. Furthermore, a postexercise reduction in pulmonary diffusion capacity suggests that the alveolo-capillary membrane is affected. An antioxidant attenuates oxidative burst by neutrophilic granulocytes, but it does not affect PaO2, SaO2 or O2 uptake (VO2), and the ventilatory response to maximal exercise also remains the same. It is proposed, though, that increased concentration of certain cytokines correlates to exercise-induced hypoxaemia as cytokines stimulate mast cells and basophilic granulocytes to degranulate histamine. The basophil count increases during maximal rowing. Equally, histamine release is associated with hypoxaemia and when the release of histamine is prevented, the reduction in PaO2 is attenuated. During maximal exercise, an extreme lactate spill-over to blood allows pH decrease to below 7.1 and according to the O2 dissociation curve this is critical for SaO2. When infusion of sodium bicarbonate maintains a stable blood buffer capacity, acidosis is attenuated and SaO2 increases from 89% to 95%. This enables exercise capacity to increase, an effect also seen when O2 supplementation to inspired air restores arterial oxygenation. In that case, exercise capacity increases less than can be explained by VO2 and CaO2. Furthermore, the change in muscle oxygenation during maximal exercise is not affected when hyperoxia and sodium bicarbonate attenuate desaturation. It is proposed that other organs benefit from enhanced O2 availability, and especially the brain appears to increase its oxygenation during maximal exercise with hyperoxia.

Antioxidant paraoxonase 1 activity in the metabolic syndrome

Paraoxonase (PON1) is an antioxidant enzyme closely associated with high-density lipoproteins. Low PON1 has been shown in oxidative stress-associated processes such as dyslipidemia, diabetes mellitus, advancing age, and smoking. Indeed, oxidative stress is related to the degree of insulin resistance, a key component of the metabolic syndrome. Therefore, the possible relationship between PON1 activity and the metabolic syndrome was investigated. From 1364 randomly recruited subjects, 285 were found to have the metabolic syndrome, according to the guidelines published by the National Cholesterol Education Program, Adult Treatment Panel III. PON1 activity, lipid peroxides, and PON1 codon 192 genotypes, which strongly modulate PON1 activity, were determined. Serum PON1 activity levels were found to be significantly lower, and lipid peroxide concentrations significantly higher, in subjects with the metabolic syndrome compared with unaffected subjects (P = 0.033 and < 0.001, respectively). Study subjects showed a significant decreasing trend in PON1 activity levels and a significant increasing trend in lipid peroxide concentrations, with the increase in the number of metabolic disturbances. No differences in the prevalence of PON1 codon 192 genotypes were found among the categories of metabolic abnormalities. In conclusion, a greater degree of severity of the metabolic syndrome is associated with a progressively worse antioxidant/oxidant balance, which is consistent with increased oxidative stress and lower antioxidant PON1 enzymatic capacity.

Rodent nutritional model of non-alcoholic steatohepatitis: species, strain and sex difference studies

BACKGROUND AND AIM

The methionine choline-deficient (MCD) diet leads to steatohepatitis in rodents. The aim of the present study was to investigate species, strain and sex differences in this nutritional model of non-alcoholic steatohepatitis (NASH).

METHODS

Male and female Wistar, Long-Evans and Sprague-Dawley rats, and C57/BL6 mice (n = 6 per group) were fed a MCD diet for 4 weeks. Control groups received an identical diet supplemented with choline bitartrate (0.2% w/w) and methionine (0.3% w/w). Liver pathology (steatosis and inflammation) and ultrastructure, liver lipid profile (total lipids, triglycerides, lipid peroxidation products), liver : body mass ratios and serum alanine aminotransferase (ALT) levels were compared between these groups.

RESULTS

The MCD diet-fed male rats developed greater steatosis (P < 0.001), had higher liver lipid content (P < 0.05) and had higher serum ALT levels (P < 0.005) than did female rats. Wistar rats (both sexes) had higher liver lipid levels (P < 0.05), serum ALT levels (P < 0.05), and liver mass : body mass ratios (P < 0.025) than did Long-Evans and Sprague-Dawley rats. In female groups, Wistar rats showed greater fatty change than did the other two strains (P < 0.05). All rats fed the MCD diet developed hepatic steatosis, but necrosis and inflammation were minor features and fibrosis was absent. Compared with Wistar rats, male C57/BL6 mice showed a marked increase in inflammatory foci (P < 0.001), end products of lipid peroxidation (free thiobarbituric acid reactive substances) (P < 0.005), and mitochondrial injury, while showing less steatosis (P < 0.005), lower hepatic triglyceride levels, (P < 0.005) and lower early lipid peroxidation products (conjugated dienes and lipid hydroperoxides; P < 0.005 and P < 0.01, respectively).

CONCLUSIONS

The Wistar strain and the male sex are associated with the greatest degree of steatosis in rats subjected to the MCD diet. Of the groups studied, male C57/BL6 mice develop the most inflammation and necrosis, lipid peroxidation, and ultrastructural injury, and best approximate the histological features of NASH.

The relationship between total sialic acid levels and antioxidant status in the tadpoles of Bufo viridis and Rana ridibunda ridibunda

Total sialic acid levels (TSA), antioxidant enzymes activities such as superoxide dismutase (SOD), catalase (CAT) and lipid peroxidation (LPO) levels were investigated during the developmental period in tadpoles of the predominantly terrestrial amphibian B. viridis and the predominantly aquatic amphibian R. r. ridibunda. Maximum TSA levels were observed in B. viridis and R. r. ridibunda at the fifth and third week of their development, respectively. SOD and CAT activity variations during development in B. viridis were higher than in R. r. ridibunda. Although SOD activity in B. viridis was higher than R. r. ridibunda at the eighth week, SOD activity increased 19.2-fold in R. r. ridibunda and 10.4-fold in B. viridis between the first and eighth week. CAT activity in R. r. ridibunda did not significantly change (p>0.001) until the fifth week then increased, whereas in B. viridis CAT increased after the third week. In contrast to the rise in the antioxidant enzyme activities, LPO levels tended to decrease during the developmental period. Levels of LPO showed a similar trend until the third week for both species. The minimum LPO levels in B. viridis and R. r. ridibunda were 23+/-1.2 and 146+/-7.3 nmol MDA g(-1) tissue, at the eighth week, respectively. While decreasing LPO levels correlated with increasing antioxidant enzyme activities, TSA tended to decrease after reaching a maximum point.

Myocardial metabolism on off-pump surgery; a randomized study of 50 cases

OBJECTIVE

To study the inflammatory reaction and myocardial metabolism in off-pump and on-pump coronary artery bypass patients.

DESIGN

Fifty coronary artery bypass patients were randomized to off-pump or on-pump operations. Myocardial biopsies were taken to determine myocardial metabolism and inflammation (glutathione (GSH), superoxide dismutase (SOD) and myeloperoxidase (MP)) and plasma samples for indicators of oxidative stress (conjugated dienes (s-BDC), oxidative products of proteins (s-ox-Prot) and low-density lipoprotein (LDL)-total peroxyl radical trapping antioxidant potential (s-TRAP)).

RESULTS

s-ox-Prot 10 min was 2.11 +/- 0.75 vs 2.69 +/- 0.60 (p = 0.014), s-TRAP 5 min was 861 +/- 180 vs 969 +/- 192 (p = 0.032) and s-TRAP 10 min 857 +/- 176 vs 985 +/- 166 (p = 0.011), GSH 10 min 0.55 +/- 0.19 vs 0.72 +/- 1.16 (p = 0.007) (off-pump vs on-pump). The monobasic (MB) fraction of the creatinine kinase 24 h after the operation was significantly lower in the off-pump group, 20.5 +/- 24.2 vs 61.8 +/- 84.6 (p = 0.023).

CONCLUSION

GSH levels from the biopsies were increased in the perfusion group early in the reperfusion time showing that myocardial tissue was well protected and recovered more rapidly after cross-clamping than after the occlusion of the coronary arteries. However, release of creatinine kinase was lower in the off-pump group showing that cardiopulmonary bypass has more deleterious effects later after the operation.

High oxidative stress in patients with stable coronary heart disease

Oxidized low density lipoprotein (oxLDL) plays a pivotal role in the development of atherosclerosis. The aim of the study was to investigate the relationship between oxLDL and other oxidative stress biomarkers with stable coronary heart disease (CHD). We compared the degree of oxidative stress in patients with CHD and sex-matched healthy control subjects in a case-control study. The study included 64 male subjects: 32 patients with stable CHD and 32 normal control subjects. Levels of circulating oxLDL were measured by a monoclonal antibody 4E6-based competition ELISA. Comparison of oxidative stress marker levels between cases and controls, adjusted for age, revealed significantly higher plasma oxLDL levels (63.32+/-25.49 vs. 37.73+/-20.58 U/l, P=0.001), lower serum levels of autoantibodies against oxLDL (341.53+/-350.46 vs. 796.45+/-1034.2 mU/ml, P=0.021), higher activities of the antioxidant enzymes superoxide dismutase in erythrocytes (951+/-70.2 vs. 771.6+/-191.2 U/g, P=0.032) and glutathione peroxidase in whole blood (GSH-Px: 10714.4+/-3705.4 vs. 5512.2+/-1498.1 U/l, P<0.001). The risk of having CHD was 20.6-fold greater (95% CI, 1.86-228.44, P=0.014) in the highest tertile of the oxLDL distribution than in the lowest, determined by logistic regression analysis on the combined study population after adjustment for age and other potential confounding factors. When the risk associated with GSH-Px levels was calculated, the odds ratio was 305.3 (95% CI, 5.07-18369.95, P=0.006) in the highest tertile compared with the lowest. Our results showed that an oxidative stress occurs in patients with CHD despite being clinically stable and under medical treatment. The combination of oxLDL levels and GSH-Px activity may be useful for the identification of patients with stable CHD.

Interrelationship of smoking, paraoxonase activity, and leisure time physical activity: a population-based study

METHODS: We determined the effect of smoking on PON1 activity levels in a population-based sample of 1380 subjects and examined the possibility of regular physical activity modulating the effect of cigarette smoking on PON1 activity levels at a population level. RESULTS: Mean PON1 activity was significantly lower in smokers than in non- or ex-smokers (237.6+/-8.4 vs. 276.7+/-5.3 U/l, mean+/-S.E.M.; P= 0.001). PON1 activity levels were significantly higher in physically active subjects than in those who were inactive (296.1+/-10.4 vs. 260.1+/-9.2 U/l; P=0.002). Inactive smokers showed significantly lower PON1 activity levels than inactive nonsmokers (P=0.002). These differences disappeared when active nonsmokers were compared with active smokers. Serum PON1 activity levels were found to be significantly increased in active smokers compared to those in inactive smokers. A statistically significant interaction (P=0.003) between smoking and physical activity on PON1 activity was observed. CONCLUSION: Smoking appears to have a deleterious effect on PON1 activity levels. Being physically active clearly attenuates this effect.

Plasma lipid composition and LDL oxidation

Low-density lipoprotein (LDL) oxidation in vivo depends on lipid composition and on plasma antioxidant status. The aim of our study was to investigate the relationship between plasma lipid composition and LDL oxidation and, in particular, to explore whether LDL-cholesterol/triglycerides ratio (LDL-C/TG) and LDL-cholesterol/high-density lipoprotein (HDL)-cholesterol ratio (LDL-C/HDL-C) can be used as predictive parameters of LDL oxidation in vivo. In 87 volunteers over a wide range of age plasma lipids and LDL oxidation were studied. Blood was collected after 12 h overnight fast. LDL oxidation was estimated by the level of conjugated diene (BDC) in the lipid fraction isolated from plasma after gradient ultra-centrifugation. The results were expressed as micromol/l (BDC/l) to evaluate the level of oxidized LDL, and as nmol of BDC for mg of LDL-cholesterol (BDC/LDL-C) for the evaluation of LDL oxidation degree. BDC/l correlated significantly with age, total and LDL-C, apolipoprotein B and TG, while BDC/LDL-C negatively correlated with total cholesterol, apolipoprotein B, LDL/TG and LDL/HDL ratios. Age of subjects significantly correlated with total and LDL-C and apolipoprotein B. TG have a significant inverse correlation with HDL-C. Our results support the hypothesis that among the several factors involved in LDL oxidation the most important determinants are LDL/TG. Plasma triglycerides appear to be very important even when circulating cholesterol levels are within normal limits. Moreover, we found that the LDL/HDL ratio is also very important with regard to the putative protective role of HDL against LDL oxidation in vivo. In conclusion, plasma lipid parameters must be evaluated not only for their absolute values but also for their mutual ratios as expression of plasma lipid homeostasis. Both LDL/TG and LDL/HDL ratios can be used as predictive parameters of in vivo LDL oxidation.

Relationship between physical activity and oxidative stress biomarkers in women

PURPOSE

To examine the relationship between physical activity and levels of plasma lipid peroxides, superoxide dismutase in erythrocytes (SOD), and glutathione peroxidase (GSH-Px) in whole blood activities.

METHODS

Cross-sectional study in 488 Spanish women. Two categories of leisure time physical activity were defined according to their intensity: low (<or=6 METs) and high (>6 METs). Energy expenditure in household activities was also recorded. Multivariate linear regression analyses were used to adjust for the effect of physical activity on lipid peroxides and SOD and GSH-Px for confounding variables.

RESULTS

The amount of leisure time physical activity was associated with high activity levels of SOD (P = 0.022) and GSH-Px (P = 0.002). Similar results were obtained when physical activity in household activities was added to total leisure physical activity. Physical activity of low intensity was associated with high SOD activity levels (P = 0.002) and that of high intensity with high GSH-Px activity levels (P = 0.001).

CONCLUSION

The amount and intensity of leisure physical activity were directly related to both antioxidant enzyme activity levels. The findings of this study suggest a modulatory effect of leisure physical activity intensity on antioxidative balance in the studied female population.

A simple assay for the measurement of plasma antioxidant status using spontaneous autoxidation of homovanillic acid

INTRODUCTION

Reactive oxygen species (ROS) contribute to the development of pathophysiological processes, hence the increasing interest in modulating the antioxidant status of patient by nutritional or pharmacological intervention. Antioxidants act by preventing the formation of ROS (inhibitory effect) and/or by trapping these species (scavenger effect). We have developed a simple, sensitive, and reliable test to measure the total antioxidative efficiency of plasma or other biological fluids using microliter samples.

METHODS

Autoxidation of homovanillic acid (HVA) gives rise to fluorescent dimers. Antioxidants contained in the plasma (or free aqueous solutions) scavenge the ROS involved in this process and transiently stop the linear increase in fluorescence intensity during a time (delay) proportional to the total concentration of antioxidants and their scavenging efficiency. In addition to this scavenging effect, the kinetics of HVA autoxidation, restarting after the delay, reflects the ability of the plasma antioxidants to inhibit the ROS-triggered autoxidation.

RESULTS

The rate of the HVA autoxidation depended on the temperature, the protonation of the phenolic group, and on the presence of peroxide, peroxyl radicals, and peroxidase as well as metal ions. This Fenton-like reaction was transiently stopped by various ROS scavengers including quercetin, ascorbic acid, and thiol derivatives (glutathione and N-acetylcystein) while metal chelating agents such as desferrioxamine, ethylene diamine tetracetic acid (EDTA), and polyamine only reduced its rate.

DISCUSSION

The main advantages of this new assay are its versatility to investigate in a single run both the scavenging and inhibitory components of the antioxidant capacity, and its relevance to the reactive hydroxyl radical. As shown in this study, the increase in the antioxidant capacity of human plasma during pharmacological supplementation with antioxidant illustrates one of the various fields of application of this assay.

L-Arginine in lung graft preservation and reperfusion

BACKGROUND

Inhaled nitric oxide has been shown to ameliorate early lung graft dysfunction. It improves oxygenation by inducing pulmonary vasodilatation in well-ventilated lung areas, and it also modulates leukocyte-endothelium interactions. We used a porcine, single lung transplantation model to evaluate whether the benefits of exogenously administered gas could be achieved easier by adding L-arginine, the substrate of endogenous nitric oxide synthesis, as an additive to the flush solution and intravenously during reperfusion.

METHODS

Six pig lungs were flushed with modified Euro-Collins solutions containing L-arginine (2 g/liter). After cold (4 degrees C) storage, the left lung was transplanted. Ischemic time was 260 minutes. The recipients received intravenous boluses of L-arginine (30 mg/kg), followed by infusion (20 mg/kg/min) during the first 30 minutes of reperfusion. Six control animals received saline as placebo. We measured the blood flow and pulmonary vascular resistance (PVR) in the transplanted and in the native lung using a right heart bypass model. We measured blood gases, leukocyte counts, plasma free-radical trapping capacity, and diene conjugates in pulmonary venous blood and myeloperoxidase activity of the lung tissue.

RESULTS

Pulmonary vascular resistance was 4 to 5-fold higher in the transplanted lung than in the native lung, which received 80% of the total blood flow. L-arginine reduced PVR by 30% in the native lung (p < 0.001), but not in the transplanted lung. L-arginine had no effect on oxygenation or carbon dioxide exchange of the transplanted lung. Nor did L-arginine treatment have any effect on leukocyte sequestration or myeloperoxidase activity in the transplanted lung. The plasma antioxidant capacity in venous blood of the transplanted lung almost doubled shortly during early reperfusion without influence of L-arginine.

CONCLUSIONS

L-arginine reduced PVR in the native lung but did not improve pulmonary hemodynamics, gas exchange, or reduce leukocyte sequestration of the transplanted lung.

Dissociation Constants of Substituted Aryl Azo Barbituric and Thiobarbituric Acids

The acid dissociation constants of 5-(substituted phenylazo) barbituric and thiobarbituric acids were determined in aqueous media and in 25–75% (v/v) ethanol–water and dioxane–water mixtures potentiometrically in the temperature range 25–40 °C, in presence of 0.5 M KCl. The values of the enthalpy change ΔH (kJ mol

Effect of soy-based breakfast cereal on blood lipids and oxidized low-density lipoprotein

Consumption of soy protein may reduce the risk of cardiovascular disease both through reduction in serum lipids and by the antioxidant properties of protein-associated soy isoflavones. However, the effect that processing required for the manufacture of breakfast cereals may have on the lipid lowering and antioxidant activities of soy has not been studied. We have therefore assessed the health benefits of soy incorporation into breakfast cereals. Twenty-five hyperlipidemic men and women took soy (providing 36 g/d soy protein and 168 mg/d isoflavones) and control breakfast cereals, each for 3 weeks in a randomized crossover study with a 2-week washout period between treatments. Fasting blood samples were obtained pretreatment and at weeks 2 and 3 of each treatment. No significant difference was seen in serum lipids between treatments at week 3 apart from a 3.8% +/- 1.5% higher apolipoprotein A-1 level on control versus soy (P = .021). However, oxidized low-density lipoprotein (LDL) was reduced on the test compared with the control both as total dienes in LDL and as the ratio of conjugated dienes to cholesterol in the LDL fraction by 9.2% +/- 4.3% (P = .042) and 8.7% +/- 4.2% (P = .050), respectively. High isoflavone intakes in soy breakfast cereals may decrease the risk of cardiovascular disease by reducing oxidized LDL, while having no significant effect on the absolute concentration of LDL cholesterol.

Effect of simvastatin therapy on paraoxonase activity and related lipoproteins in familial hypercholesterolemic patients

Human paraoxonase (PON1) is a calcium-dependent esterase closely associated with high density lipoprotein (HDL)-containing apolipoprotein AI (apoAI), which has been shown to confer antioxidant properties to HDL. PON1 has been recently implicated in the pathogenesis of atherosclerosis. Low PON1 activities have been found in familial hypercholesterolemia (FH) and diabetes mellitus. We have undertaken a study of the effect of the lipid-lowering drug simvastatin on serum PON1 activity (in relation to paraoxon and arylesterase activity), on apoAI-containing and apolipoprotein B (apoB)-containing lipoproteins, and on lipid peroxide concentrations in 64 (39 women and 25 men) unrelated FH patients. We have also analyzed the influence of the PON1-192 and PON1-55 genetic polymorphisms on the response of PON1 activity to simvastatin therapy. A venous blood sample for a baseline analysis and another after 4 months of simvastatin therapy at a dosage of 20 mg per day were taken. The major effect of simvastatin on lipid traits was to decrease serum cholesterol, low density lipoprotein (LDL) cholesterol, and lipid peroxide concentrations by 19.9%, 26.3%, and 37.3%, respectively. There was also a significant decrease in serum apoB, LDL apoB, and triglyceride concentrations (20.5%, 21.1%, and 15.6%, respectively). Conversely, simvastatin had no significant influence on very low density lipoprotein-lipid content, HDL cholesterol, apoAI concentrations, and lipoprotein AI and AI:AII particles. Remarkably, serum PON1 activity toward paraoxon significantly increased during treatment with simvastatin (168. 7+/-100.3 U/L before therapy versus 189.5+/-116.5 U/L after therapy, P:=0.005). Arylesterase activity displayed only a nonsignificant trend to increase after therapy. Whereas PON1 activity levels were significantly lower in FH patients before simvastatin therapy compared with those of 124 normolipidemic subjects (168.7+/-100.3 versus 207.6+/-125.2 U/L, respectively; P:<0.05), this difference disappeared after simvastatin therapy. After simvastatin therapy, a significantly negative correlation between PON1 activity and lipid peroxide concentration was observed (r=-0.35, P:=0.028). The latter also strongly correlated with LDL cholesterol concentration (r=0.64, P:<0.001). Serum PON1 activity levels were significantly lower in the low-activity PON1-192 QQ and PON1-55 M carriers than in R carriers and in LL carriers, respectively. No significant differences were found in the therapeutic response of PON1 activity between genotype groups (8.5% and 11.1% increase for QQ homozygous and R-carrier FH patients, respectively, and 12.7% and 9.5% increase for LL homozygotes and M carriers, respectively). We conclude that simvastatin may have important antioxidant properties through increasing serum PON1 activity, perhaps as a consequence of reducing oxidative stress, by a mechanism independent of apoAI-containing lipoprotein concentration and without the influence of PON1-192 and PON1-55 genetic polymorphisms. Further studies are clearly warranted to clarify the precise mechanism by which simvastatin therapy is associated with increased PON1 activity.

Oxidant stress in sled dogs subjected to repetitive endurance exercise

OBJECTIVE

To determine whether repetitive endurance exercise in sled dogs was associated with substantial lipid peroxidation, decreases in antioxidant capacity of the serum, and skeletal muscle damage.

ANIMALS

24 lightly trained sled dogs.

PROCEDURE

16 dogs completed a 58-km run on each of 3 consecutive days; the other 8 dogs (control) did not exercise during the study. Blood samples were collected before the first exercise run and after the first and third exercise runs. Plasma isoprostane and serum vitamin E concentrations, total antioxidant status of plasma, and serum creatine kinase activity were measured.

RESULTS

Plasma isoprostane concentrations in dogs in the exercise group were significantly increased after the first exercise run and further significantly increased after the third exercise run. Serum vitamin E concentration was significantly decreased after the first exercise run in dogs in the exercise group, and this change persisted after the third exercise run. There was a significant linear relationship between plasma isoprostane concentration and the logarithm of serum creatine kinase activity (adjusted ? = 0.84).

CONCLUSIONS AND CLINICAL RELEVANCE

Results demonstrate that repetitive endurance exercise in dogs is associated with lipid peroxidation and a reduction in plasma antioxidant concentrations. We interpret these results as indicating that the antioxidant mechanisms of minimally trained dogs may, in some instances, be inadequate to meet the antioxidant requirements of repetitive endurance exercise.