A comparative evaluation of thiobarbituric acid methods for the determination of malondialdehyde in biological materials

Absorption of andrographolides from Andrographis paniculata and its effect on CCl(4)-induced oxidative stress in rats

A simple and validated high-performance liquid chromatography (HPLC) method with UV detection has been used to determine the content of andrographolide (AP) and 14-deoxy-11,12-didehydroandrographolide (DIAP) in rat plasma after oral dose of methanol extract (1 g/kg body weight) of Andrographis paniculata leaf. An increase in plasma concentration of AP and DIAP was observed from 30 min to 3 h after oral administration of the extract. The maximum plasma concentrations of AP and DIAP were 1.42+/-0.09 microg/ml and 1.31+/-0.04 microg/ml, respectively. Fourteen days oral treatment of rats with the methanol extract (1 g/kg body weight) followed by CCl(4) administration preserved catalase (CAT), and superoxide dismutase (SOD) activities in erythrocytes, whereas plasma lipid peroxidation, alanine transaminase (ALT) and aspartate transaminase (AST) activities were restored to values comparable with control values. Treatment of rats with CCl(4) did not showed significant alteration (p>0.05) in plasma total antioxidant status (TAS) as compare to values of control group.

N-Acetylcysteine amide protects against methamphetamine-induced oxidative stress and neurotoxicity in immortalized human brain endothelial cells

Oxidative stress plays an important role in neurodegenerative disorders such as Parkinson's disease and Alzheimer's disease. Methamphetamine (METH) is an amphetamine analog that causes degeneration of the dopaminergic system in mammals and subsequent oxidative stress. In our present study, we have used immortalized human brain microvascular endothelial (HBMVEC) cells to test whether N-acetylcysteine amide (NACA), a novel antioxidant, prevents METH-induced oxidative stress in vitro. Our studies showed that NACA protects against METH-induced oxidative stress in HBMVEC cells. NACA significantly protected the integrity of our blood brain barrier (BBB) model, as shown by permeability and trans-endothelial electrical resistance (TEER) studies. NACA also significantly increased the levels of intracellular glutathione (GSH) and glutathione peroxidase (GPx). Malondialdehyde (MDA) levels increased dramatically after METH exposure, but this increase was almost completely prevented when the cells were treated with NACA. Generation of reactive oxygen species (ROS) also increased after METH exposure, but was reduced to control levels with NACA treatment, as measured by dichlorofluorescin (DCF). These results suggest that NACA protects the BBB integrity in vitro, which could prevent oxidative stress-induced damage; therefore, the effectiveness of this antioxidant should be evaluated for the treatment of neurodegenerative diseases in the future.

Antihyperglycemic, antioxidant and antiglycation activities of mulberry leaf extract in streptozotocin-induced chronic diabetic rats

In Thailand, beverages containing mulberry leaf (Morus alba L.) are believed to promote good health, especially in people with diabetes. We examined the effects of long-term administration of an ethanolic extract of mulberry leaf (MA) on blood glucose, oxidative damage, and glycation in streptozotocin-induced diabetic rats. Daily administration of 1 g/kg MA for six weeks decreased blood glucose by 22%, which was comparable to the effect of 4 U/kg insulin. Lipid peroxidation, measured as malondialdehyde and lipid hydroperoxide concentrations (3.50 +/- 0.33 and 3.76 +/- 0.18 muM, respectively) decreased significantly (P < 0.05) compared to nontreated control diabetic rats (8.19 +/- 0.45 and 7.50 +/- 0.46 muM, respectively). Hemoglobin A(1C), a biomarker for chronic exposure to high concentration of glucose, was also significantly decreased in the MA-treated group (6.78 +/- 0.30%) in comparison to untreated group (9.02 +/- 0.30%). The IC(50) of in vitro antiglycation and free radical scavenging activities of MA were 16.4 +/- 5.6 microg/ml and 61.7 +/- 2.1 microg/ml, respectively. These findings support that long-term administration of MA has antihyperglycemic, antioxidant and antiglycation effects in chronic diabetic rats, which may be beneficial as food supplement for diabetics.

Involvement of nitric oxide in acute lung inflammation induced by cigarette smoke in the mouse

Short-term exposure to cigarette smoke (CS) leads to acute lung inflammation (ALI) by disturbing oxidant/antioxidant balance. Both CS exposure and lung inflammation are important risk factors in the pathogenesis of chronic obstructive pulmonary disease. Nitric oxide (NO) is an oxidant both present in CS and produced in the inflammatory response, but its role in the effects of CS exposure is unclear. Our aim was to study involvement of NO in a model of CS exposure. Groups of mice (male C57BL/6) exposed to CS (six cigarettes per day over five days) were simultaneously subjected to treatment with vehicle (CS), 60mg/kg/day omega-nitro-l-arginine methyl ester (CS+l-NAME), 20mg/kg/day nitroglycerine (CS+NTG), or 120mg/kg/day l-arginine (CS+l-arg). Bronchoalveolar lavage fluid was then aspirated to perform cell counts, and malondialdehyde (MDA), nitrite, catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) levels were measured in lung homogenates. Macrophage and neutrophil counts were increased in the CS (p<0.001) and CS+l-NAME groups (p<0.05 and p<0.01, respectively); the CS+NTG and CS+l-arg groups showed no differences from the control group. MDA was increased in the CS (p<0.05) and CS+l-NAME (p<0.01) groups when compared to the control group. Nitrite levels were decreased in the CS and CS+l-NAME groups (p<0.001) and increased in the CS+NTG (p<0.001) and CS+l-arg (p<0.01) groups when compared to the control. CAT, SOD and GPx activities in the CS and CS+l-NAME groups were all significantly increased compared to the control group. Our results suggest that administration of NO donors or substrates may be a useful therapy in the treatment of ALI caused by CS.

N-acetylcysteine amide decreases oxidative stress but not cell death induced by doxorubicin in H9c2 cardiomyocytes

Background

While doxorubicin (DOX) is widely used in cancer chemotherapy, long-term severe cardiotoxicity limits its use. This is the first report of the chemoprotective efficacy of a relatively new thiol antioxidant, N-acetylcysteine amide (NACA), on DOX-induced cell death in cardiomyocytes. We hypothesized that NACA would protect H9c2 cardiomyocytes from DOX-induced toxicity by reducing oxidative stress. Accordingly, we determined the ability of NACA to mitigate the cytotoxicity of DOX in H9c2 cells and correlated these effects with the production of indicators of oxidative stress.

Results

DOX at 5 μM induced cardiotoxicity while 1) increasing the generation of reactive oxygen species (ROS), 2) decreasing levels and activities of antioxidants and antioxidant enzymes (catalase, glutathione peroxidase, glutathione reductase) and 3) increasing lipid peroxidation. NACA at 750 μM substantially reduced the levels of ROS and lipid peroxidation, as well as increased both GSH level and GSH/GSSG ratio. However, treating H9c2 cells with NACA did little to protect H9c2 cells from DOX-induced cell death.

Conclusion

Although NACA effectively reduced oxidative stress in DOX-treated H9c2 cells, it had minimal effects on DOX-induced cell death. NACA prevented oxidative stress by elevation of GSH and CYS, reduction of ROS and lipid peroxidation, and restoration of antioxidant enzyme activities. Further studies to identify oxidative stress-independent pathways that lead to DOX-induced cell death in H9c2 are warranted.

N-acetylcysteine amide decreases oxidative stress but not cell death induced by doxorubicin in H9c2 cardiomyocytes

BACKGROUND

While doxorubicin (DOX) is widely used in cancer chemotherapy, long-term severe cardiotoxicity limits its use. This is the first report of the chemoprotective efficacy of a relatively new thiol antioxidant, N-acetylcysteine amide (NACA), on DOX-induced cell death in cardiomyocytes. We hypothesized that NACA would protect H9c2 cardiomyocytes from DOX-induced toxicity by reducing oxidative stress. Accordingly, we determined the ability of NACA to mitigate the cytotoxicity of DOX in H9c2 cells and correlated these effects with the production of indicators of oxidative stress.

RESULTS

DOX at 5 microM induced cardiotoxicity while 1) increasing the generation of reactive oxygen species (ROS), 2) decreasing levels and activities of antioxidants and antioxidant enzymes (catalase, glutathione peroxidase, glutathione reductase) and 3) increasing lipid peroxidation. NACA at 750 microM substantially reduced the levels of ROS and lipid peroxidation, as well as increased both GSH level and GSH/GSSG ratio. However, treating H9c2 cells with NACA did little to protect H9c2 cells from DOX-induced cell death.

CONCLUSION

Although NACA effectively reduced oxidative stress in DOX-treated H9c2 cells, it had minimal effects on DOX-induced cell death. NACA prevented oxidative stress by elevation of GSH and CYS, reduction of ROS and lipid peroxidation, and restoration of antioxidant enzyme activities. Further studies to identify oxidative stress-independent pathways that lead to DOX-induced cell death in H9c2 are warranted.

A BRCA1 mutation is not associated with increased indicators of oxidative stress

BACKGROUND

Several functions have been attributed to the BRCA1 protein. A recent study suggests that BRCA1 is involved in the cellular antioxidant response by inducing the expression of genes involved in the antioxidant defense system and thus conferring resistance to oxidative stress. It is possible that individuals with a BRCA1 mutation might be susceptible to the effects of oxidative stress. The aim of this study was to evaluate whether women with a BRCA1 mutation exhibit increased indicators of oxidative stress.

PATIENTS AND METHODS

We measured 3 markers of oxidative stress in vivo, the amounts of serum malondialdehyde and protein thiols, and 8-oxo-2'-deoxyguanosine (8-oxodG) levels in 25 unaffected BRCA1 mutation carriers and 25 noncarrier control subjects.

RESULTS

There was no significant difference in serum malondialdehyde levels (P=.41), serum thiol levels (P=.85), or the number of 8-oxodG lesions (P=.49) in BRCA1 mutation carriers versus noncarriers.

CONCLUSION

The results of this study suggest that the presence of a heterozygous BRCA1 mutation is not associated with increased levels of indicators of oxidative stress in serum or lymphocytes. Future studies are warranted to evaluate whether strategies aimed at minimizing oxidative stress might aid in the prevention of hereditary breast cancer.

An alternative exercise and its beneficial effects on glycaemic control and oxidative stress in subjects with type 2 diabetes

This study investigated the effect of arm swing exercise (ASE) on glycaemic control and oxidative stress in type 2 diabetic patients. The results suggest a protective effect of the ASE training on vascular complications by improving oxidative stress in according to either improved glycaemic control or exercise per se.

Local treatment of experimental colitis in the rat by negatively charged liposomes of catalase, TMN and SOD

Superoxide dismutase (SOD), 4-amino tempol (tempamine, denoted as TMN) and catalase were encapsulated into negatively charged liposomes. The activity of the antioxidants against dinitrobenzenesulfonic acid (DNBS) induced colitis was tested in the rat and compared to the anti-inflammatory activity of the native enzymes and free TMN. Inflammation severity was assessed by monitoring tissue myeloperoxidase (MPO) activity, thiobarbituric acid reactive species (TBARS) amounts and by comparing the weights of the dissected colons. In all cases, the liposomal preparations of the antioxidants were more effective than the free molecules in the treatment of the experimental colitis, probably due to the attachment of the negatively charged liposomes, and consequently a longer residence time and better uptake of the antioxidants to the inflamed mucosa. This study suggests that low and high molecular weight antioxidants delivered via anionic liposomes can serve as a novel targeted therapy to treat chronic inflammation of the colonic epithelium, such as ulcerative colitis.

Oxidative stress in mouse plasma and lungs induced by cigarette smoke and lipopolysaccharide

Short-term exposure to cigarette smoke (CS) or lipopolysaccharide (LPS) leads to acute lung inflammation through oxidant-antioxidant imbalance. We studied the response in mice exposed to smoke or LPS during five consecutive days, as measured by superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities, as well as lipid peroxidation and nitric oxide levels in bronchoalveolar lavage fluid (BALF), lung homogenates, and plasma. Control mice were exposed to ambient air. Exposure to CS or LPS led to a similar influx of alveolar macrophages and neutrophils into the BALF; however, hydroxyproline levels were increased only in the CS group (p<0.001); SOD activity was increased in the BALF (p<0.001) and lung homogenates (p<0.05) of the CS group but was decreased in the BALF (p<0.05), lung homogenates (p<0.05) and plasma (p<0.01) of the LPS group. CAT activity was increased in the BALF (p<0.01), lung homogenates (p<0.001) and plasma (p<0.05) of the CS group but decreased in the BALF (p<0.001) and plasma (p<0.05) of the LPS group. GPx activity was reduced in the BALF (p<0.01) and plasma (p<0.01) of both the CS and LPS groups. Lipid peroxidation was increased in the BALF (p<0.001) and lung homogenates (p<0.001) of the CS group. Finally, the levels of nitrite were reduced in the CS (p<0.01) and LPS (p<0.001) groups. Our data show that the activity profiles of enzymes contributing to oxidant-antioxidant imbalance in the lungs differ depending on the inflammatory stimulus, and that SOD, CAT and GPx may be useful markers of oxidative stress in acute lung inflammation induced by exposure to CS.

Photo-induced toxicity of four polycyclic aromatic hydrocarbons, singly and in combination, to the marine diatom Phaeodactylum tricornutum

Polycyclic aromatic hydrocarbons (PAHs) enter the aquatic environment by various routes and are usually found as mixtures in the water. Many studies have shown that solar ultraviolet (UV) radiation can greatly enhance the toxicity of some PAHs to a variety of marine species. In the present study, we tested the phototoxicity of four PAHs with simple structures, both alone and in binary combinations, to a species of marine diatom, Phaeodactylum tricornutum, in the laboratory. The results indicated that simulated solar UV radiation not only enhanced the toxicity of the different PAHs to this alga, but also changed their relative toxic strengths. The photo-induced toxicity of PAHs to this alga might be a synergistic effect of photo-modification and photosensitization reactions, causing the microalgal cells to suffer oxidative stress. Four binary mixtures of these PAHs were found to have a synergistic joint action mode, while two binary mixtures displayed an antagonistic reaction, revealing a complex pattern of possible interactions of PAHs with marine diatoms.

Antioxidative role of selenium on some tissues of (Cd2+), Cr3+)-induced rainbow trout

Chemical toxic pollutants (especially heavy metals) are important sources of reactive oxygen species (ROS) in biological systems. Membrane phospholipids of aerobic organisms are continually subjected to oxidant challenges from endogenous and exogenous sources, while peroxidized membranes and lipid peroxidation products represent constant threats to aerobic cells. The primary antioxidant protection against free radical and ROS is provided by the enzymes glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and catalase (CAT), respectively. The trace element selenium has been implicated in chemo-prevention and drug-resistance through reduction of oxidative stress. Selenium could prevent damage to the unsaturated fatty acid of subcellular membranes by lipid peroxidation induced by free radicals. The results reported here show that sodium selenite has an important contribution to antioxidative defense for the spleen and heart of rainbow trout. The ability of sodium selenite to prevent the oxidative stress induced by heavy metals (Cd(2+), Cr(3+)) in fish was rationalized.

Antioxidative role of selenium against the toxic effect of heavy metals (Cd+2, Cr+3) on liver of rainbow trout (Oncorhynchus mykiss Walbaum 1792)

The main purpose of this study is to discuss the effect of Cd+2, Cr+3 and Se metals on biochemical parameters in liver tissue of Oncorhynchus mykiss. The rainbow trout were exposed to heavy metal stress (Cd+2, Cr+3) at 2 ppm dosage. The present study was undertaken to determine the protective effect of selenium treatment at the same dosage (2 ppm) on some biochemical parameters. The activity of catalase (CAT), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and the changes in levels of malondialdehyde (MDA) from biochemical parameters were determined in liver tissue of the fish groups exposed to heavy metals, especially for the selenium-applied groups. Results of this study showed that the activities of CAT, GSH-Px and SOD in the tissues of fish exposed to the stress of Cd+2 and Cr+3 were significantly lower than the control groups (P < 0.05). Meanwhile, the closer values to the control groups were obtained in selenium-added groups (Cr+3 + Se+4, Cd+2 + Se+4). For the level of MDA, the last production of lipid peroxidation showed increases (P < 0.05) in the groups exposed to the metal stress, whereas significant decreases were obtained in selenium-applied groups. The result of the statistical evaluation showed that the negative effects occurring in the biochemical parameters of the applied groups exposed to the toxicity of heavy metal were significantly eliminated (P < 0.05) as a result of selenium treatment.

Antioxidant activity of Bol d'Air Jacquier breathing sessions in Wistar rats--first studies

OBJECTIVES

The Bol d'Air Jacquier is used to create a molecule able to deliver oxygen at the cellular level to manage hypoxia due to environmental pollution, ageing, or inflammatory disease. This study was designed to determine, firstly, whether the device generated oxidative stress and, secondly, whether it might induce an antioxidant effect.

MATERIAL AND METHODS

Over a period of 62 weeks, 10 male Wistar rats were randomized into two groups: the Bol d'Air group (BA) regularly breathed peroxidizing terpens delivered by the device and the control group breathed water vapour during 9-min sessions, at the frequency of 1-12 per month. Several antioxidant compounds and KRL levels were determined in the blood and major organs.

RESULTS

The results showed that the two groups did not differ with respect to the organ concentrations of Cu, Zn SOD, GPx, GSH, GSSG and TBARS. The device might have a weak slimming effect over time. The BA group presented a significantly higher GR level in plasma throughout the experiment, and in the muscle at the end of the study. In the BA group, the plasma Cu, Zn SOD level was related to the number of breathing sessions per week before blood collection. The BA group also had a higher KRLantioxidant status at two different time-points: at the onset of the study, in the blood of young rats; and after three breathing sessions per week, in the blood and RBCs of old rats.

CONCLUSIONS

The device did not generate oxidative stress and seemed to produce global antioxidant effect depending on the number of sessions per week, especially in old rats.

Prevention of leukocyte activation by the neutrophil elastase inhibitor, sivelestat, in the hepatic microcirculation after ischemia-reperfusion

BACKGROUND

Liver ischemia-reperfusion (I/R) injury is one of the most serious complications of hepatic surgery. However, no effective treatment is yet clinically available. Although neutrophil elastase inhibitor (NEI) has been used clinically in acute lung injury, the effect of NEI on leukocyte dynamics in the liver microcirculation after hepatic I/R remained unclear. The purpose of this study was to use intravital microscopy (IVM) to evaluate the effect of NEI on leukocyte dynamics in the liver microcirculation after hepatic I/R.

METHODS

Hepatic ischemia was induced in male Sprague-Dawley (SD) rats. Sivelestat, a specific NEI, or normal saline (NS) was given as a continuous intravenous infusion before ischemia. The number of adherent leukocytes and the disturbances of sinusoidal perfusion in hepatic microcirculation were observed up to 120 min after reperfusion. Samples of liver tissue and blood were taken for histological examination and measurement of liver enzymes and tissue malondialdehyde (MDA).

RESULTS

Compared with NS, sivelestat significantly decreased the number of adherent leukocytes and prevented perfusion disturbance. In addition, sivelestat obviously improved liver injury as assessed by histological findings and liver enzymes, and prevented the increase of MDA.

CONCLUSIONS

Administration of sivelestat before ischemia effectively suppressed the activation of leukocytes and lipid peroxide, and it consequently prevented hepatic I/R injury.

HPLC determination of malondialdehyde in ECV304 cell culture medium for measuring the antioxidant effect of vitexin-4''-O-glucoside

To investigate the antioxidant effect of vitexin-4''-O-glucoside, a flavone glycoside, isolated from the leaves of Crataegus pinnatifida Bge. var. major, we developed a simple and sensitive high-performance liquid chromatography (HPLC) method to determine levels of malondialdehyde (MDA) in ECV304 cell culture medium after induction by tert-butyl-hydroperoxide (TBHP). The preparation of analyzed samples involved a one-step derivatization with thiobarbituric acid (TBA). HPLC analysis was performed on a Synergi Hydro-RP, a polar end-capped C18 column (250 x 4.6 mm, 4 mum), using an acetonitrile-ammonium acetate aqueous solution (10 mM, pH 6.8) as the mobile phase under linear gradient conditions with UV detection at 532 nm. The calibration curve was linear over 0.0125-1.25 microM MDA (r = 0.9951). Relative standard deviations (RSDs) of intra-day and inter-day precision were less than 6.1% and 5.0%, respectively. The mean recovery was 96.9 +/- 1.6%. The lower limit of quantification (LLOQ) of MDA was 0.0125 microM. This chromatographic method was successfully applied to investigating the in vitro antioxidant effect of vitexin-4''-O-glucoside. Vitexin-4''-O-glucoside (120 M) protected ECV304 cells from peroxidation induced by TBHP.

Preventive effect of aminoguanidine compared to vitamin E and C on cisplatin-induced nephrotoxicity in rats

In this study, the antioxidant effect of aminoguanidine on nephrotoxicity of a single dose of cisplatin is investigated and compared with the effects of well-known antioxidants vitamin C and E combination. Tubular damage and perivascular inflammation were observed in kidney samples of the cisplatin-administered groups. Aminoguanidine and vitamin C-E combination are found to be capable of preventing these effects of cisplatin. Liver tissues of all groups were intact. Cisplatin-induced oxidative stress was evidenced by significant decrease in glutathione and significant increase in malondialdehyde levels in kidney samples. Antioxidants with cisplatin decreased malondialdehyde levels. Antioxidants with cisplatin prevented the decrease in liver glutathione levels. The nephrotoxicity was confirmed biochemically by significant elevation of serum urea and creatinine levels. Both vitamin C-E combination and aminoguanidine prevented the increase in serum urea levels according to the cisplatin group.

Automated derivatization and analysis of malondialdehyde using column switching sample preparation HPLC with fluorescence detection

Analyte derivatization is advantageous for the analysis of malondialdehyde (MDA) as a biomarker of oxidative stress in biological samples. Conventionally, however, derivatization is time consuming, error-prone and has limited options for automation. We have addressed these challenges for the solid phase analytical derivatization of MDA from small volume tissue homogenate samples. A manual derivatization method was first developed using Amberlite XAD-2 (12 mg) as the solid phase. Subsequently an automated column switching process was developed that provided simultaneous derivatization and extraction of the MDA-DH hydrazone product on a cartridge packed with XAD-2, followed by quantitative elution of the product to an analytical LC column (Waters NovoPak C18, 3.9 x 150 mm). The LOD was 0.02 microg/mL and recovery was quantitative. The method was linear (r(2) >0.999) with precision < 5% from the LOQ (0.06 microg/mL) to at least 35 microg/mL. The method was successfully applied to the analysis of small volume (30 microL) mouse tissue homogenate samples. Endogenous levels of MDA in the tissues ranged from 20 to 40 nmol/g tissue (ca. 0.1-0.2 microg/mL homogenate). Compared to conventional MDA analyses, the current method has advantages in automation, selectivity, precision and sensitivity for analysis from very small sample volumes.

Effects of N-acetylcysteine amide (NACA), a thiol antioxidant on radiation-induced cytotoxicity in Chinese hamster ovary cells

Ionizing radiation is known to cause tissue damage in biological systems, mainly due to its ability to produce reactive oxygen species (ROS) in cells. Many thiol antioxidants have been used previously as radioprotectors, but their application has been limited by their toxicity. In this investigation, we have explored the possible radioprotective effects of a newly synthesized thiol antioxidant, N-acetylcysteine amide (NACA), in comparison with N-acetylcysteine (NAC), a commonly used antioxidant. Protective effects of NACA and NAC were assessed using Chinese hamster ovary (CHO) cells, irradiated with 6 gray (Gy) radiation. Oxidative stress parameters, including levels of reduced glutathione (GSH), cysteine, malondialdehyde (MDA), and activities of antioxidant enzymes like glutathione peroxidase, glutathione reductase, and catalase, were measured. Results indicate that NACA was capable of restoring GSH levels in irradiated cells in a dose dependent manner. In addition, NACA prevented radiation-induced loss in cell viability. NACA further restored levels of malondialdehyde, caspase-3 activity, and antioxidant enzyme activities to control levels. Although NAC affected cells in a similar manner to NACA, its effects were not as significant. Further, NAC was also found to be cytotoxic to cells at higher concentrations, whereas NACA was non-toxic at similar concentrations. These results suggest that NACA may be able to attenuate radiation-induced cytotoxicity, possibly by its ability to provide thiols to cells.

Toxic effects of fluoranthene and copper on marine diatom Phaeodactylum tricornutum

To investigate the effects of polycyclic aromatic hydrocarbons (PAHs) and metals on the population reproduction, antioxidative defense system and cell ultrastructure of the marine diatom, fluoranthene and Cu2+ were selected to test their toxicity to Phaeodactylum tricorntum, in the laboratory. The results indicated that both fluoranthene and Cu2+ inhibited population reproduction of P. tricorntum. When the algal cells were exposed to fluoranthene or Cu2+ for 72 h, ultrastructure damage in the cells was observed under a Transmission Electron Microscope (TEM). The chloroplast was a sensitive organelle and the membrane system was very sensitive to the toxicity of fluoranthene or Cu2+. The normal metabolic process might be affected due to cell ultrastructural impairment. However, it needed further investigation to discern whether the ultrastructural damage was responsible for the inhibition of population reproduction. Malondialdehyde (MDA) content indicating oxidative stress was a sensitive index to both fluoranthene and Cu2+ toxicity. Superoxide dismutase (SOD) activity was also a sensitive index to Cu2+ and could be considered as a reference factor in a Cu2+ pollution event, but not in a fluoranthene pollution event.

White blood cells telomere length is shorter in males with type 2 diabetes and microalbuminuria

OBJECTIVE

To examine differences in telomere (terminal restriction fragment [TRF]) length and pulse wave velocity (PWV)--an index of arterial stiffness--in patients with type 2 diabetes with and without microalbuminuria (MA).

RESEARCH DESIGN AND METHODS

A total of 84 men with type 2 diabetes, 40 with MA and 44 without MA (aged 63.5 +/- 9.0 vs. 61.2 +/- 9.8 years), were studied. TRF length was determined in white blood cells. MA was defined as albumin excretion rate (AER) in the range of 30-300 mg/24 h in at least two of three 24-h urine collections. PWV was assessed using applanation tonometry. Markers of oxidative stress were also measured.

RESULTS

TRF length was shorter in patients with MA than in those without MA (6.64 +/- 0.74 vs. 7.23 +/- 1.01 kb, respectively, P = 0.004). PWV was significantly higher in the patients with MA. Multivariate linear regression analysis in the total sample demonstrated an independent association between TRF length and age (P = 0.02), MA status (P = 0.04) or AER (P = 0.002), and plasma nitrotyrosine levels (P = 0.02). AER was associated significantly with PWV (P < 0.01).

CONCLUSIONS

Subjects with type 2 diabetes and MA have shorter TRF length and increased arterial stiffness than those without MA. Additionally, TRF length is associated with age, AER, and nitrosative stress. As shorter TRF length indicates older biological age, the increased arterial stiffness in patients with type 2 diabetes who have MA may be due to the more pronounced "aging " of these subjects.

Redistribution of metal ions to control low density lipoprotein oxidation in Ham's F10 medium

The study of cell-mediated low density lipoprotein (LDL) oxidation has traditionally been undertaken using Ham's F10 media due to its high metal content and low levels of antioxidants. Although there has been no acknowledged change to this media in recent years by the suppliers, Ham's F10 medium has been found to be extremely inconsistent in its promotion of LDL oxidation in the absence of cells. This variability contrasts with the relatively consistent rates of THP-1 cell-mediated LDL oxidation. This study has now shown that the variability in cell-free LDL oxidation is medium-dependent and not an artefact of experimental protocol. It presents evidence that suggests the variable rates of cell-free LDL oxidation are caused by iron auto-oxidation during storage of the Ham's F10 medium. The medium can be standardized by removal of all transition metals, by treatment with Chelex, before the addition of known amounts of iron or copper. This treatment generates a cell culture medium that only allows very slow LDL oxidation in the absence of cells.

LipoCardium: Endothelium-directed cyclopentenone prostaglandin-based liposome formulation that completely reverses atherosclerotic lesions

Atherosclerosis is a multifactorial inflammatory disease of blood vessels which decimates one in every three people in industrialized world. Despite the important newest clinical approaches, currently available strategies (e.g. nutritional, pharmacological and surgical) may only restrain the worsening of vascular disease. Since antiproliferative cyclopentenone prostaglandins (CP-PGs) are powerful anti-inflammatory agents, we developed a negatively charged liposome-based pharmaceutical formulation (LipoCardium) that specifically direct CP-PGs towards the injured arterial wall cells of atherosclerotic mice. In the blood stream, LipoCardium delivers its CP-PG contents only into activated arterial wall lining cells due to the presence of antibodies raised against vascular cell adhesion molecule-1 (VCAM-1), which is strongly expressed upon inflammation by endothelial cells and macrophage-foam cells as well. After 4 months in a high-lipid diet, all low-density lipoprotein receptor-deficient adult control mice died from myocardium infarction or stroke in less than 2 weeks, whereas LipoCardium-treated (2 weeks) animals (still under high-lipid diet) completely recovered from vascular injuries. In vitro studies using macrophage-foam cells suggested a tetravalent pattern for LipoCardium action: anti-inflammatory, antiproliferative (and pro-apoptotic only to foam cells), antilipogenic and cytoprotector (via heat-shock protein induction). These astonishing cellular effects were accompanied by a marked reduction in arterial wall thickness, neointimal hyperplasia and lipid accumulation, while guaranteed lifespan to be extended to the elderly age. Our findings suggest that LipoCardium may be safely tested in humans in a near future and may have conceptual implications in atherosclerosis therapy.

Antioxidant properties of Krebs cycle intermediates against malonate pro-oxidant activity in vitro: A comparative study using the colorimetric method and HPLC analysis to determine malondialdehyde in rat brain homogenates

A variety of Krebs cycle intermediaries has been shown to possess antioxidant properties in different in vivo and in vitro systems. Here we examined whether citrate, succinate, malate, oxaloacetate, fumarate and alpha-ketoglutarate could modulate malonate-induced thiobarbituric acid-reactive species (TBARS) production in rat brain homogenate. The mechanisms involved in their antioxidant activity were also determined using two analytical methods: 1) a popular spectrophotometric method (Ohkawa, H., Ohishi, N., Yagi, K., 1979. Assay for lipid peroxides in animal tissues by thiobarbituric acid reaction. Analytical Biochemistry 95, 351-358.) and a high performance liquid chromatographic (HPLC) procedure (Grotto, D., Santa Maria, L. D., Boeira, S., Valentini, J., Charão, M. F., Moro, A. M., Nascimento, P. C., Pomblum, V. J., Garcia, S. C., 2006. Rapid quantification of malondialdehyde in plasma by high performance liquid chromatography-visible detection. Journal of Pharmaceutical and Biomedical Analysis 43, 619-624.). Citrate, malate, and oxaloacetate reduced both basal and malonate-induced TBARS production. Their effects were not changed by pre-treatment of rat brain homogenates at 100 degrees C for 10 min. alpha-Ketoglutarate increased basal TBARS without changing malonate-induced TBARS production in fresh and heat-treated homogenates. Succinate reduced basal--without altering malonate-induced TBARS production. Its antioxidant activity was abolished by KCN or heat treatment. Fumarate reduced malonate-induced TBARS production in fresh homogenates; however, its effect was completely abolished by heat treatment. There were minimal differences among the studied methods. Citrate, oxaloacetate, malate, alpha-ketoglutarate and malonate showed iron-chelating activity. We suggest that antioxidant properties of citrate, malate and oxaloacetate were due to their ability to cancel iron redox activity by forming inactive complexes, whereas alpha-ketoglutarate and malonate pro-oxidant activity can be due to formation of active complexes with iron. In contrast, succinate and fumarate antioxidant activity was probably due to some enzymatic system.

Effect of cigarette smoking on the oxidant/antioxidant balance in healthy subjects

BACKGROUND AND PURPOSE

Cigarette smoking has been associated with the development of cardiovascular disease and cancer. Even though the molecular mechanism(s) are not clear, the pathology has been related to oxygen free radicals present in cigarette smoke. Thus, the main objective of this study was to establish the changes in the oxidation/antioxidation balance induced by cigarette smoking.

METHODS

Thirty healthy subjects (15 smokers and 15 nonsmokers) of both sexes were studied. The smokers group had smoked a mean of 14 cigarettes per day for an average of 4.5 years. Fasting serum levels of malondialdehyde (MDA), a marker of oxidative stress, nitric oxide (NO), reduced glutathione (GSH), and vitamin C (ascorbic and dehydroascorbic acids) were measured.

RESULTS

Fasting NO concentration was significantly higher in smokers (51.3 +/- 5.3 microM) than in nonsmokers (35.2 +/- 4.8 microM, P < 0.05). The smokers had significantly higher serum dehydroascorbic acid levels (2.4 +/- 0.5 mg/dL, P < 0.03) than the nonsmokers (1.08 +/- 0.08 mg/dL). No significant differences were observed in the levels of ascorbic acid, MDA, and GSH between the smokers and nonsmokers.

CONCLUSIONS

Our results suggest that exposure to cigarette smoke increases NO synthesis, such that NO may act in a compensatory way as an inhibitor of lipid peroxidation. Smoking also activates other antioxidative mechanisms such as involving vitamin C. These protective mechanisms appear to be enough in preventing accumulation of oxidative products such as MDA and avoiding oxidative damage.

Increased DNA damage in children caused by passive smoking as assessed by comet assay and oxidative stress

The present study aimed to evaluate the association between the environmental tobacco smoke (ETS) and DNA damage in relation to oxidative stress (OS) in children. Sixty-four children of age 1-8 years, selected from the outpatient clinic of Mansoura University Children Hospital were divided into two groups (23 children/group) based on high (>20 cigarettes/day) or low (<20 cigarettes/day) exposure to ETS at home. Twenty symptom-free children with normal cotinine level and with no exposure to ETS were recruited as controls. The comet assay was used to quantify the level of DNA damage in lymphocytes isolated from all children. Spectrophotometric methods were used to assess the serum level of malondialdehyde (MDA) and activity of glutathione peroxidase (GSH-Px) in erythrocytes. Also, serum level of tocopherol fractions (alpha, gamma, delta) was assessed by high performance liquid chromatography (HPLC). Children exposed to ETS exhibited retarded growth, more chest problems, and gastroenteritis than the control. A significant increase in mean comet tail length indicating DNA damage was observed in ETS-exposed children (P<0.001) compared to controls. ETS-exposed children had significantly (P<0.001) higher MDA level paralleled with significant (P<0.001) decrease in the level of GSH-Px and tocopherol fractions compared with controls. The GSH-Px activity and tocopherol levels were inversely correlated with the increase of ETS exposure. These results show that inhalation of ETS is associated with an increase in the level of oxidants and a simultaneous decrease in the level of antioxidants in the children's blood. This status of oxidant-antioxidant imbalance (OS) may be one of the mechanisms leading to DNA damage detected in lymphocytes of ETS-exposed children. In conclusion, the present study gives an indication of an association between DNA damage and ETS exposure in children.

Effects of supportive treatment such as antioxidant or leukotriene receptor antagonist drugs on inflammatory and respiratory parameters in asthma patients

In this study, prospectively, we aimed to determine the effects of the different treatment alternatives on the oxidant system and inflammatory and clinic determinants during the stable period of 1 month following an asthmatic attack. Thirty-one patients (22 female, nine male) were randomly divided into three groups following the stabilization of an acute asthma attack. The control group that is an additional group to the three patient groups consisted of 10 healthy volunteers (five female, five male). The following protocols were used for 4 weeks: Group I: short-acting inhaler beta2 mimetic as required (treatment A)+800 mug inhaler budesonide (treatment B)+leukotriene receptor antagonist; Group II: treatment A and B; Group III: treatment A and B+vitamin E. The serum levels before and after treatment of eosinophilic cationic protein (ECP), leukotriene E4 (LTE(4)), and malondialdehyde (MDA) were determined. The values before and after treatment were statistically compared both with each other and control values. Pretreatment ECP, LTE(4), and MDA levels for the three groups were significantly higher compared with post-treatment levels (P<0.05 to P<0.001) and the control levels (P<0.01 to P<0.001). However, when post-treatment levels were compared with those of the control group, no significant differences were found (P>0.05). Lack of significant variation was observed when the pre- and post-treatment differences in the three groups were compared for each one of ECP, LTE(4), and MDA levels (P>0.05). Leukotriene receptor antagonist or antioxidant agents added to standard asthma treatment did not make a significant contribution on ECP, LTE(4), and MDA levels and respiratory parameters such as spirometric function tests. Etiologic factors and/or the possible changes in different pathogenetic ways of the inflammation process may have been responsible for nonsignificant intertreatment difference in the biomarker levels. The result confirms that suppressing the inflammation in asthma enables the entire inflammatory pathologic process to be controlled.

Antioxidant and vascular protective activities of Cratoxylum formosum, Syzygium gratum and Limnophila aromatica

Phytochemicals contained in dietary plants provide a variety of health benefits and may reduce the risk of cardiovascular diseases. The aqueous extracts from three popular Thai dietary and herbal plants, Cratoxylum formosum, Syzygium gratum, and Limnophila aromatica, were investigated for the antioxidant and vascular protective activities in the in vitro and in vivo models. The free radical scavenging and antioxidant activities of plant extracts were evaluated in vitro by the 1,1-diphenyl-2-picrylhydrazyl assay, the ferric reducing antioxidant power assay, the intracellular antioxidant activity in rat peritoneal macrophages by dihydrofluorescein assay, and the inhibition of nitric oxide (NO) production in RAW 264.7 macrophages. In an animal model of oxidative stress and vascular dysfunction, male Sprague-Dawley rats were orally administered with aqueous plant extracts (1 g/kg/d) or N-acetylcysteine (NAC; 300 mg/kg/d) as a control for 6 d. On day four, all animals except the normal control group, were administered with phenylhydrazine (PHZ) intraperitoneally. It was demonstrated that the plant extracts possessed high free radical scavenging and antioxidant activities. PHZ induced severe hemolysis and hemodynamic disturbances and treatment with the extracts and NAC significantly improved the hemodynamic status. Vascular responsiveness to bradykinin, acetylcholine, and phenylephrine in PHZ-control rats was markedly impaired, and the plant extracts or NAC largely restored the vascular responses. Moreover, the plant extracts prevented loss of blood reduced glutathione and suppressed formation of plasma malondialdehyde, plasma NO metabolites and blood superoxide anion. It was concluded that the plant extracts possess antioxidants and have potential roles in protection of vascular dysfunction.

Protective effects of quercetin against phenylhydrazine-induced vascular dysfunction and oxidative stress in rats

Oxidative stress is a major contributor to the development of vascular dysfunction found in various pathological conditions. Quercetin, one of the potent antioxidant bioflavonoid compounds, has been shown to alleviate oxidative injury by modulation of gene expression leading to suppression of production of reactive oxygen and nitrogen species and conferring an antiapoptotic activity. The aim of the present study was to investigate the protective effects of quercetin in a model of phenylhydrazine (PHZ)-induced oxidant stress, vascular dysfunction and hemodynamic disturbance in rats. Male Sprague-Dawley rats were administered quercetin orally (25 or 50mg/kg/day) for 6 days. On day four, all animals except those in the normal control group, were administered PHZ intraperitoneally. The results showed that PHZ induced severe hemolysis. The mean arterial pressure and hindlimb vascular resistance of PHZ-control rats were markedly decreased compared to normal controls. Treatment with quercetin significantly improved arterial blood pressure and peripheral vascular resistance. Vascular responsiveness to bradykinin, acetylcholine, and phenylephrine in PHZ-control rats was dramatically suppressed and quercetin restored these responses in a dose-dependent manner. Quercetin partially protected blood glutathione, suppressed plasma malondialdehyde levels, and largely suppressed nitric oxide metabolites and superoxide anion production. These results provide the first evidence for the role of the flavonoid, quercetin, in the alleviation of vascular dysfunction in an animal model of PHZ-induced oxidant stress.

Exercise-induced increase in lipid peroxidation in patients with chronic heart failure: relation to exercise intolerance

BACKGROUND

Little is known about the relationship between exercise intolerance and lipid peroxidation in chronic heart failure (CHF) patients. This study was designed to investigate the relationship between exercise-induced plasma malondialdehyde (MDA) changes in CHF patients and to determine whether there is any association between plasma MDA levels and exercise capacity assessed by cardiopulmonary exercise testing.

METHODS

Cardiopulmonary exercise testing was applied to 31 CHF patients (16 ischemic, 15 idiopathic) and controls. Rest and peak exercise blood samples were analyzed for MDA.

RESULTS

Patients with CHF had elevation of plasma MDA levels during exercise compared with controls (p < 0.001 vs. p = 0.588). MDA change remained significant both in ischemic and idiopathic cardiomyopathy groups (p < 0.05 and p < 0.01, respectively). Delta MDA (peak exercise MDA - rest MDA) showed significant inverse correlation with peak oxygen consumption in patients with CHF.

CONCLUSION

Lipid peroxidation is increased in patients with CHF during exercise regardless of etiology, and this increase is inversely related to oxygen consumption.

Modification of CYP2E1 and CYP3A4 activities in haemoglobin E-beta thalassemia patients

OBJECTIVE

Thalassemia disease is a genetic haemoglobinopathy usually associated with an iron overload and some degree of organ impairment. The impact of the disease on the drug metabolising enzyme cytochrome P450 (CYP) is not known. CYP2E1 and CYP3A4 are responsible for the metabolism of a large number of drugs and changes in their activities may have clinical consequences.

METHODS

Haemoglobin E-beta thalassemia paediatric, blood transfusion-dependent patients apparently without complications (n = 35) and healthy controls (n = 42) were recruited in this study. The ratios of plasma 6-hydroxychlorzoxazone to chlorzoxazone, and urinary 6-beta-hydroxycortisol (6beta-OHF) to cortisol were used as indices for CYP2E1 and CYP3A4 activities, respectively. Blood and plasma samples were assayed for parameters of clinical biochemistry, oxidants and antioxidants.

RESULTS

There were significant increases in serum iron, protein carbonyl and lipid peroxidation in thalassemia patients, whereas there was a decrease in blood glutathione, but unchanged plasma nitric oxide metabolites. CYP2E1 activity in the patients was unchanged; however, when the patients were stratified by splenectomy status, CYP2E1 activity was increased in non-splenectomised patients in comparison with the controls and splenectomised subjects. On the other hand, 6beta-OHF/cortisol ratios increased markedly in patients associated with depressed growth hormone levels. There were no correlations between CYP2E1 activity and oxidant stress or antioxidant parameters.

CONCLUSIONS

This report is the first demonstration that thalassemia major is associated with an alteration of CYP2E1 and CYP3A4 activities; this could modify the sensitivity of thalassemia patients to the toxic or therapeutic effects of drugs.

Lycopene consumption decreases oxidative stress and bone resorption markers in postmenopausal women

INTRODUCTION

Oxidative stress induced by reactive oxygen species (ROS) is associated with the risk of osteoporosis, and can be reduced by certain dietary antioxidants. Lycopene is an antioxidant known to decrease the risk of age-related chronic diseases, such as cancer. However, the role of lycopene in osteoporosis has not yet been investigated.

MATERIALS AND METHODS

In a cross-sectional study, 33 postmenopausal women aged 50-60 years provided seven-day dietary records and blood samples. Serum samples were used to measure serum lycopene, lipid peroxidation, protein thiols, bone alkaline phosphatase (BAP), and cross-linked N-telopeptides of type I collagen (NTx). The serum lycopene per kilogram body weight of the participants was grouped into quartiles and associated with the above serum parameters using one-way ANOVA and the Newman-Keuls post-test.

RESULTS

The results showed that groups with higher lycopene intake, as determined from the dietary records, had higher serum lycopene (p<0.02). A higher serum lycopene was found to be associated with a low NTx (p<0.005). Similarly, groups with higher serum lycopene had lower protein oxidation (p<0.05).

DISCUSSION

In conclusion, these results suggest that the dietary antioxidant lycopene reduces oxidative stress and the levels of bone turnover markers in postmenopausal women, and may be beneficial in reducing the risk of osteoporosis.

Comparison of spectrophotometric and HPLC methods for determination of lipid peroxidation products in rat brain tissues

Two methods for determination of lipid peroxidation (LPX) products in rat brain homogenates were compared. The thiobarbituric acid (TBA) test and HPLC assay for analysis of malondialdehyde (MDA) were applied. Rat brain homogenate dissolved in tris(hydroxymethyl)aminomethane hydrochloride (Tris-HCl) was mixed with TBA and H3PO4 and heated at 100°C to form colored complex that was extracted into butanol. No significant differences were found between the contents of TBA-reacting substances and their amount deduced from the MDA-TBA analysis. The presented results show that LPX products in brain homogenates can be determined without interferences also by the TBA test. Moreover, a survey of various methods used for the sample preparation before analysis of LPX products originating from different brain areas was made and compared with the obtained results.

Early specific free radical-related cytotoxicity of gas phase cigarette smoke and its paradoxical temporary inhibition by tar: An electron paramagnetic resonance study with the spin trap DEPMPO

Electron paramagnetic resonance (EPR) spin trapping studies demonstrated aqueous tar particulate matter (TPM) and gas phase cigarette smoke (GPCS) to behave as different sources of free radicals in cigarette smoke (CS) but their cytotoxic implications have been only assessed in CS due to its relevance to the natural smoking process. Using a sensitive spin trapping detection with 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline-N-oxide (DEPMPO), this study compared the respective roles of CS- and GPCS-derived free radicals on smoke-induced cytotoxicity and lipid peroxidation of filtered and unfiltered, machine-smoked experimental and reference cigarettes yielding a wide range of TPM yields. In buffer bubbled with CS the DEPMPO/superoxide spin adduct was the major detected nitroxide. Use of appropriate control experiments with nitric oxide radical (NO*) or carbonyl sulfide, and a computer analysis of spin adduct diastereoisomery showed that the hydroxyl radical (HO*) adduct of DEPMPO seen in GPCS-bubbled was rather related to metal-catalyzed nucleophilic synthesis than to direct HO* trapping. Unexpectedly a protective effect of TPM on murine 3T3 fibroblasts was observed in early (<3h) free radical-, GPCS-induced cell death, and carbon filtering decreased free radical formation, toxicity and lipid peroxidation in three cell lines (including human epithelial lung cells) challenged with GPCS. These results highlight an acute, free radical-dependent, harmful mechanism specific to the GPCS phase, possibly involving NO* chemistry, whose physical or chemical control may be of great interest with the aim of reducing the toxicity of smoke.

In vitro toxicity of silica nanoparticles in human lung cancer cells

The cytotoxicity of 15-nm and 46-nm silica nanoparticles was investigated by using crystalline silica (Min-U-Sil 5) as a positive control in cultured human bronchoalveolar carcinoma-derived cells. Exposure to 15-nm or 46-nm SiO(2) nanoparticles for 48 h at dosage levels between 10 and 100 microg/ml decreased cell viability in a dose-dependent manner. Both SiO(2) nanoparticles were more cytotoxic than Min-U-Sil 5; however, the cytotoxicities of 15-nm and 46-nm silica nanoparticles were not significantly different. The 15-nm SiO(2) nanoparticles were used to determine time-dependent cytotoxicity and oxidative stress responses. Cell viability decreased significantly as a function of both nanoparticle dosage (10-100 microg/ml) and exposure time (24 h, 48 h, and 72 h). Indicators of oxidative stress and cytotoxicity, including total reactive oxygen species (ROS), glutathione, malondialdehyde, and lactate dehydrogenase, were quantitatively assessed. Exposure to SiO(2) nanoparticles increased ROS levels and reduced glutathione levels. The increased production of malondialdehyde and lactate dehydrogenase release from the cells indicated lipid peroxidation and membrane damage. In summary, exposure to SiO(2) nanoparticles results in a dose-dependent cytotoxicity in cultural human bronchoalveolar carcinoma-derived cells that is closely correlated to increased oxidative stress.

Biventricular versus right ventricular pacing decreases immune activation and augments nitric oxide production in patients with chronic heart failure

INTRODUCTION

Immune system activation and oxidative stress are involved in the pathogenesis of heart failure (HF). We aimed to test the hypothesis that upgrading from right ventricular pacing (RVp) to biventricular pacing (BiVp) can counteract these phenomena.

METHODS

28 HF patients, with BiVp were switched to RVp for one week, and then returned to BiVp. Immediately prior to, and 48 h after the return to BiVp, left ventricular (LV) systolic function was evaluated by echocardiography, and serum N-terminal pro-brain natriuretic peptide (NTproBNP), C-reactive protein (CRP), tumor necrosis factor alpha (TNF-alpha), interleukin 6 (IL6), nitric oxide metabolites (NO(x)) and malondialdehyde (MDA) were assayed.

RESULTS

LV systolic function significantly improved 48 h after switching from RVp to BiVp: Ao-VTI (p<0.001), SV (p<0.001) and CO (p<0.001), and mitral regurgitation significantly decreased (p=0.003). At the same time, indices of peripheral immune activation decreased: TNF-alpha (p=0.02) and IL6 (p<0.001). MDA decreased (p<0.001), whereas NO(x) increased (p=0.04). NTproBNP and CRP did not change. In addition, in "responders" (i.e. CO increase >10% during BiVp vs. RVp) NTproBNP decreased and NO(x) increased. However, during BiVp, the decreases in TNF-alpha, IL6, and MDA occurred both in responders and in non-responders and were accompanied by a reduction in mitral regurgitation.

CONCLUSION

The beneficial effect of BiVp compared to RVp extends beyond improving cardiac haemodynamics and comprises a decrease in immune activation accompanied by an increase in serum NO(x) and decrease in serum MDA.

Estimation of lipoperoxidative damage and antioxidant status in diabetic children: relationship with individual antioxidants

Increased oxidative stress has emerged as a potential mechanism implicated in the pathogenesis, progression and cell dysfunction associated with many diseases including diabetes. In routine clinical practice, the estimation of the degree of oxidative damage and antioxidant status, even in paediatric patients, by appropriate techniques appears to be of interest. The aim of this study was to reliably identify patients with increased oxidant stress and/or reduced antioxidant defence mechanisms with a small blood sample and verify the applicability to the study of diabetic children (DC) at clinical onset of the disease. In 1-ml blood samples from 30 DC and 34 controls, techniques for accurately measuring malondialdehyde (MDA) concentrations in plasma and erythrocytes (using HPLC analysis with fluorometric detection), total radical antioxidant potential (TRAP) and blood plasma oxidizability were adapted and validated. Plasma alpha-tocopherol (HPLC), uric acid and sulfhydryl (SH) groups were also determined. At clinical onset of diabetes a significant reduction in plasma TRAP values (P<0.01) was observed in DC compared with controls. Similarly, a significant fall in individual antioxidant levels (alpha-tocopherol/total lipids, uric acid and protein SH) was noted in plasma of DC. Highly significant increases were found in both plasma and erythrocyte MDA levels in DC (p-MDA:1.7+/-0.2 microM; er-MDA: 7.2+/-0.7 nmol/g Hb) compared with controls (p-MDA:0.86+/-0.09 microM; P<0.0003; er-MDA:3.8+/-0.2 nmol/g Hb, P<0.0001). Plasma MDA and triglyceride levels correlated directly only in DC (P<0.001). Whole plasma oxidizability was significantly higher in DC than in controls (P<0.0001) and this parameter correlated significantly with plasma cholesterol and triglyceride concentrations (P<0.0001). The micromethods adapted and applied to the simultaneous detection of lipid peroxidation products and antioxidant status permit accurate and reliable assessment of the oxidative stress process in small plasma samples. Our results clearly show systemic peroxidative damage associated with insufficient defence mechanisms against ROS to be already present at clinical onset of type 1 diabetes mellitus in children and adolescents.

Effects of selenocystine on lead-exposed Chinese hamster ovary (CHO) and PC-12 cells

Lead is a pervasive environmental toxin that affects multiple organ systems, including the nervous, renal, reproductive, and hematological systems. Even though it is probably the most studied toxic metal, some of the symptoms of lead toxicity still cannot be explained by known molecular mechanisms. Therefore, lead-induced oxidative stress has recently started to gain attention. This in vitro study confirms the existence of oxidative stress due to lead exposure. Administration of lead acetate (PbA) to cultures of Chinese hamster ovary cells (CHO) had a concentration-dependent inhibitory effect on colony formation and cell proliferation. This inhibition was eliminated by 5 microM selenocystine (SeCys). In order to evaluate the nature of SeCys's effect, we measured glutathione (GSH), its oxidized form glutathione disulfide (GSSG), malondialdehyde (MDA), catalase, and GSH peroxidase (GPx) activities in lead-exposed CHO cells both in the presence and absence of SeCys. Increases in MDA, catalase, and GPx activities were observed in cultures that received only PbA, but supplementation with SeCys returned these measures to pretreatment levels. The ratio of GSH to GSSG increased in lead-exposed cells incubated in SeCys-enhanced media but declined in cultures treated with PbA only. In order to determine whether SeCys also reverses lead-induced neurotoxicity, a neuronal cell line, PC-12 cells, was used. Lead's inhibition on neurite formation was significantly eliminated by SeCys in PC-12 cells. Our results suggest that SeCys can confer protection against lead-induced toxicity in CHO cells and neurotoxicity in PC-12 cells.

Potentiation of lead-induced cell death in PC12 cells by glutamate: protection by N-acetylcysteine amide (NACA), a novel thiol antioxidant

Oxidative stress has been implicated as an important factor in many neurological diseases. Oxidative toxicity in a number of these conditions is induced by excessive glutamate release and subsequent glutamatergic neuronal stimulation. This, in turn, causes increased generation of reactive oxygen species (ROS), oxidative stress, excitotoxicity, and neuronal damage. Recent studies indicate that the glutamatergic neurotransmitter system is involved in lead-induced neurotoxicity. Therefore, this study aimed to (1) investigate the potential effects of glutamate on lead-induced PC12 cell death and (2) elucidate whether the novel thiol antioxidant N-acetylcysteine amide (NACA) had any protective abilities against such cytotoxicity. Our results suggest that glutamate (1 mM) potentiates lead-induced cytotoxicity by increased generation of ROS, decreased proliferation (MTS), decreased glutathione (GSH) levels, and depletion of cellular adenosine-triphosphate (ATP). Consistent with its ability to decrease ATP levels and induce cell death, lead also increased caspase-3 activity, an effect potentiated by glutamate. Exposure to glutamate and lead elevated the cellular malondialdehyde (MDA) levels and phospholipase-A(2) (PLA(2)) activity and diminished the glutamine synthetase (GS) activity. NACA protected PC12 cells from the cytotoxic effects of glutamate plus lead, as evaluated by MTS assay. NACA reduced the decrease in the cellular ATP levels and restored the intracellular GSH levels. The increased levels of ROS and MDA in glutamate-lead treated cells were significantly decreased by NACA. In conclusion, our data showed that glutamate potentiated the effects of lead-induced PC12 cell death by a mechanism involving mitochondrial dysfunction (ATP depletion) and oxidative stress. NACA had a protective role against the combined toxic effects of glutamate and lead by inhibiting lipid peroxidation and scavenging ROS, thus preserving intracellular GSH.