The total peroxyl radical-trapping ability of plasma and cerebrospinal fluid in normal and preeclamptic parturients

Cerebrospinal fluid and plasma ascorbate concentrations following subarachnoid haemorrhage

Background

Ascorbate, the biologically active form of vitamin C, is the primary neural anti-oxidant. Ascorbate concentrations have never been quantified following aneurysmal subarachnoid haemorrhage (aSAH).

Objective

To quantify plasma and cerebrospinal fluid (CSF) ascorbate concentrations in patients following SAH.

Design Setting Participants Main Outcome Measures

Cohort study in which plasma and CSF ascorbate concentrations were measured longitudinally in 12 aSAH patients admitted to a quaternary referral intensive care unit and compared to one-off samples obtained from 20 pregnant women prior to delivery in a co-located obstetric hospital. Data are median [interquartile range] or median (95 % confidence intervals).

Results

Forty-eight plasma samples were obtained from the 12 aSAH patients (eight females, age 62 [53-68] years). Eight participants with extra-ventricular drains provided 31 paired CSF-plasma samples. Single plasma and CSF samples were obtained from 20 pregnant women (age 35 [31-37] years). Initial plasma and CSF ascorbate concentrations post aSAH were less than half those in pregnant controls (plasma: aSAH: 31 [25-39] μmol/L vs. comparator: 64 [59-77] μmol/L; P < 0.001 and CSF: 116 [80-142] μmol/L vs. 252 [240-288] μmol/L; P < 0.001). Post aSAH there was a gradual reduction in the CSF:plasma ascorbate ratio from ∼4:1 to ∼1:1. Six (50 %) patients developed vasospasm and CSF ascorbate concentrations were lower in these patients (vasospasm: 61 (25, 97) vs. no vasospasm: 110 (96, 125) μmol/L; P = 0.01).

Conclusion

Post aSAH there is a marked reduction in CSF ascorbate concentration that is most prominent in those who develop vasospasm.

A comprehensive two-scale model for predicting the oxidizability of fatty acid methyl ester mixtures

The intricate mechanisms of oil thermooxidation and their accurate prediction have long been hampered by the combinatory nature of propagation and termination reactions involving randomly generated radicals. To unravel this complexity, we suggest a two-scale mechanistic description that connects the chemical functions (scale 1) with the molecular carriers of these functions (scale 2). Our method underscores the importance of accounting for cross-reactions between radicals in order to fully comprehend the reactivities in blends. We rigorously tested and validated the proposed two-scale scheme on binary and ternary mixtures of fatty acid methyl esters (FAMEs), yielding three key insights: (1) The abstraction of labile protons hinges on the carrier, defying the conventional focus on hydroperoxyl radical types. (2) Termination reactions between radicals adhere to the geometric mean law, exhibiting symmetric collision ratios. (3) The decomposition of hydroperoxides emerges as a monomolecular process above 80 °C, challenging the established combinatorial paradigm. Applicable across a wide temperature range (80 °C to 200 °C), our findings unlock the production of blends with controlled thermooxidation stability, optimizing the use of vegetable oils across applications: food science, biofuels, and lubricants.

Analytical Methods for Lipid Oxidation and Antioxidant Capacity in Food Systems

Lipid oxidation is the most crucial quality parameter in foods. Many methods were developed to determine the level of oxidation and antioxidant activity. This review compares the methods used to determine lipid oxidation and antioxidant capacity in foods. Lipid oxidation methods developed are based on the direct or indirect measurement of produced primary or secondary oxidation substances. Peroxide values and conjugated diene methods determine the primary oxidative products of lipid oxidation and are commonly used for plant oils and high-fat products. 2-Thiobarbituric acid-reactive substances and chromatographic methods are used to determine the secondary products of oxidation and are suitable for meat and meat-based products. The fluorometric and sensory analyses are indirect methods. The antioxidant capacity of additives is determined indirectly using the lipid oxidation methods mentioned above or directly based on the free-radical scavenging activity of the antioxidant compounds. Each lipid oxidation and antioxidant capacity methods use different approaches, and one method cannot be used for all foods. Therefore, selecting proper methods for specific foods is essential for accurately evaluating lipid oxidation or antioxidant capacity.

Evaluation of serum antioxidant activity in patients with liver pathology by the chemiluminescent method

Total antioxidant activity of the serum in patients with liver pathology was assessed by two chemiluminescent methods based on different models of free radical oxidation: Hb-H2O2-luminol and ABAP-luminol. Comparative analysis showed a significant, but not high correlation of the results (r=0.798), which can be explained by different mechanisms of induction of free radicals and effects of various serum components (proteins and bilirubin) on the initiation process. The influence of aphysiological concentration of analyzed values manifested in the Hb-H2O2 model. Disagreement between the results of measurements was more pronounced in patients with abnormally high serum bilirubin content. The results suggested that ABAP-luminol chemiluminescent model is more preferable for evaluation of antioxidant activity in clinical practice.

Changes in antioxidant status and cardiovascular risk factors of overweight young men after six weeks supplementation of whey protein isolate and resistance training

The study's purpose was to examine the effects of whey protein supplementation and resistance training on antioxidant status and cardiovascular risk factors in overweight young men. Thirty healthy male subjects (age, 23.4±3.6years; body mass index, 25-30kg/m(2)) were randomly divided into three groups of 10 persons including; Experimental group 1: resistance training+whey supplement (RW); Experimental group 2: resistance training+placebo (RP), and Control group (C). Subjects in intervention groups underwent 3 resistance training sessions per week, each session with 60-70% 1RM, for 6weeks. No significant changes in fibrinogen level, fasting blood glucose, resting systolic and diastolic blood pressures, waist to hip ratio (WHR), and body mass index were observed in any of the groups. Total antioxidant capacity (TAC), cholesterol and HDL varied significantly in the RW group compared with the pre-test. We found significant changes in both RW and RP groups for glutathione, vitamin C, LDL, and triglyceride levels. In addition, in the post-test, TAC, glutathione, and HDL levels were higher in the RW in comparison to C group. Research findings showed that although exercise can lead to antioxidant system improvement and reduce some cardiovascular risk factors among overweight subjects, the combination of resistance training and whey consumption is more effective.

The effect of tobacco smoking during pregnancy on plasma oxidant and antioxidant status in mother and newborn

OBJECTIVE

The aim of the study was to estimate the effect of tobacco smoking during pregnancy on oxidative damage and antioxidant defence in matched samples of maternal blood and cord blood.

STUDY DESIGN

Healthy, pregnant women (n=140) were divided into non-smoking and smoking groups according to the concentration of cotinine in serum and urine. Oxidative damage was measured through levels of malondialdehyde (MDA) and plasma antioxidant status was evaluated by measuring concentrations of total radical trapping parameters (TRAP) and selected antioxidants (β-carotene, vitamin A, vitamin E, uric acid). Statistical analysis was done using the SAS System for Windows (SAS Institute, Cary, NC).

RESULTS

In the course of pregnancy the concentration of MDA increased, but to higher values in smoking women than in non-smoking ones. It was accompanied by significantly lower TRAP in the smoking group than in the controls (p<0.05). Plasma concentration of uric acid (p<0.05) and antioxidant vitamins E (p<0.01), A and β-carotene (p<0.0001) were all reduced in smokers as compared with non-smoking pregnant women especially in the third trimester. Concentration of MDA in plasma of cord blood of newborns of smoking mothers was significantly higher (p<0.01) but the antioxidant defence was lower (p<0.0001) than in non-smoking ones. It was particularly pronounced for β-carotene (32%; p<0.0001) and vitamin A (28%; p<0.001). A significant negative correlation was found between MDA and TRAP levels of maternal plasma (non-smoking and smoking: r=-0.50, p<0.0001) and cord plasma (non-smoking: r=-0.54, p=0.0057; smoking: r=-0.71, p=0.0004) in all the study subjects. Total antioxidant status positively correlated with concentrations of uric acid and vitamin E in non-smoking and smoking mothers as well as their newborns.

CONCLUSION

Tobacco smoke enhances lipid peroxidation and depletes antioxidant potential in the plasma of pregnant women and umbilical cord blood. Therefore smoking during pregnancy may stimulate free radical damage in the mother and the growing fetus.

Physical well-being in women with a history of severe preeclampsia

OBJECTIVE

To evaluate the physical and mental health of women with a history of severe preeclampsia.

METHODS

In a historical cohort study 131 former patients with a history of severe preeclampsia and 127 control patients received questionnaires about experienced physical and mental complaints after delivery. At a follow-up visit blood pressure, body mass index, and proteinuria were measured and venous blood was drawn.

RESULTS

Former patients experienced significantly (p < 0.001) more frequent problems of headache (31% vs. 2%), right upper quadrant pain (16% vs. 1%), visual disturbances (21% vs. 1%), tiredness (66% vs. 27%), subjective loss of concentration (37% vs. 16%), and mental health (37% vs. 6%) compared with controls. When present, these health problems, except for tiredness, lasted significantly more often beyond six months postpartum compared to controls. Admittance to the intensive care unit was associated with headache, and subjective loss of memory and concentration over a longer period of time. The risk of recurrence of severe preeclampsia was a subject of concern in 20% of former patients. At follow-up, systolic and diastolic blood pressures were significantly higher (p < 0.001) among former patients.

CONCLUSION

Patients with a history of severe preeclampsia more frequently reported physical and mental complaints, also during a longer period of time.

Susceptibility of red blood cell lipids to in vitro oxidation and antioxidant status in preeclampsia

OBJECTIVE

To investigate susceptibility of red blood cell (RBC) lipids to oxidation and antioxidant status in preeclampsia.

STUDY DESIGN

Twenty-one women with mild preeclampsia, 21 women with severe preeclampsia, and 20 healthy pregnant women were included in this cross-sectional study. Susceptibility of RBC to oxidative stress was determined by measuring RBC-malondialdehyde levels after incubation with hydrogen peroxide. Vitamins E and C, total carotenoids and erythrocyte superoxide dismutase and glutathione peroxidase (GPx) activities and serum total antioxidant capacity (TAC) were determined spectrophotometrically. One-way analysis of variance and correlation analysis were used for statistical analyses.

RESULTS

Compared with the normal pregnant women, susceptibility of RBC to oxidation was enhanced in the mild (p<0.05) and severe (p<0.01) preeclampsia groups, TAC was lower in the mild (p<0.01) and severe (p<0.001) preeclampsia groups. Vitamin C level was decreased in severe preeclampsia and total carotene level was decreased in mild and severe preeclampsia groups (p<0.05). GPx activity was also decreased in the mild (p<0.01) and severe (p<0.05) preeclampsia groups.

CONCLUSION

The results of the present study supported the oxidative stress hypothesis of preeclampsia and it is possible that RBC play a role in the pathophysiology of the disease.

Prenatal Vitamin C Status is Associated with Placental Apoptosis in Normal-term Human Pregnancies

Pregnancy is associated with increased susceptibility to oxidative stress. Deficiencies in antioxidants during pregnancy and placental oxidant-antioxidant imbalance may impair the development of the fetoplacental unit or the eventual offspring. In order to elucidate the association of prenatal status of vitamin C with the oxidative stress and apoptotic activity in normal full-term placentas, we evaluated the content of placental lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) and the trophoblast apoptotic index in normal-term human pregnancies. Tissue samples of placentas obtained from 80 normal-term pregnancies were categorized into 40 cases with a lower level of prenatal vitamin C (< 8.997 microg/ml) and 40 cases with a higher level of prenatal vitamin C (> or =11.734 microg/ml). We evaluated the placental LOX-1 content and the trophoblast apoptotic index with Western blot analysis and immunohistochemistry, and then determined their correlation with the prenatal status of vitamin C. We confirmed that the trophoblast expression for the endothelial scavenger receptor LOX-1 and the apoptotic activity were significantly lower in the group with a higher prenatal level of vitamin C, indicating that placental oxidative stress and the apoptotic index were associated with the maternal status of vitamin C. We therefore postulate that the maternal status of antioxidant vitamins during pregnancy can affect fetal development.

Alterations in plasma antioxidants during reperfusion of the ischemic small intestine in rats

The aim of this study was to evaluate the contribution of three plasma antioxidants (albumin, uric acid, SH groups) to the plasma total peroxyl radical-trapping antioxidant capacity (TRAP) in 2 and 4 h of intestinal reperfusion in rats. TRAP increased significantly both after 2 and 4 h of reperfusion. Neither albumin nor SH groups contributed significantly to this increase. TRAP was strongly influenced by the increase in uric acid concentration and also probably by the cell destruction caused by oxidative stress. Since the TRAP increase was accompanied by an increase in the level of thiobarbituric acid reactive substances (TBARS, a marker of lipid peroxidation), we can conclude that even such a large increase in TRAP is not sufficient to prevent the progression of lipid peroxidation and oxidative stress.

Transcranial magnetic stimulation attenuates cell loss and oxidative damage in the striatum induced in the 3-nitropropionic model of Huntington's disease

An investigation was conducted on the effect of transcranial magnetic field stimulation (TMS) on the free radical production and neuronal cell loss produced by 3-nitropropionic acid in rats. The effects of 3-nitropropionic acid were evaluated by examining the following changes in: the quantity of hydroperoxides and total radical-trapping antioxidant potential (TRAP), lipid peroxidation products, protein carbonyl groups, reduced glutathione (GSH) content, glutathione peroxidase (GSH-Px), catalase and succinate dehydrogenase (SDH) activities; total nitrite and cell death [morphological changes, quantification of neuronal loss and lactate dehydrogenase (LDH) levels]. Our results reveal that 3-nitropropionic acid induces oxidative and nitrosative stress in the striatum, prompts cell loss and also shows that TMS prevents the harmful effects induced by the acid. In conclusion, the results show the ability of TMS to modify neuronal response to 3-nitropropionic acid.

Oxidative stress and preeclampsia: rationale for antioxidant clinical trials

Preeclampsia remains a frequent and potentially dangerous complication of pregnancy. The cause remains largely unknown, but oxidative stress and a generalized inflammatory state are features of the maternal syndrome. The placenta appears to be the principal source of free radical synthesis but maternal leukocytes and the maternal endothelium are also likely contributors. Recent reports have suggested an important role for placental trophoblast NAD(P)H oxidase in free radical generation in preeclampsia. The antioxidant vitamin E is now known to have multiple actions in addition to prevention of lipid peroxidation (ie, inhibition of NAD(P)H oxidase activation and the inflammatory response). In view of the abnormally low plasma vitamin C concentrations in preeclampsia, a combination of vitamins C and E is a promising prophylactic strategy for prevention of preeclampsia. Several multicenter randomized clinical trials are now underway. The potential use of antioxidants and the recognized, albeit modest, benefit of low-dose aspirin prophylaxis have heightened the need for a reliable predictive test for preeclampsia. A combination test involving several relevant biomarkers is likely to provide the best predictive potential.

Effects of a combined micronutrient supplementation on maternal biological status and newborn anthropometrics measurements: a randomized double-blind, placebo-controlled trial in apparently healthy pregnant women

OBJECTIVE

To investigate the possible beneficial effects of a micronutrient supplementation to apparently healthy pregnant women on maternal biological status and new born anthropometric characteristics.

SETTING

Departments of Obstetric of the University Hospital of Grenoble (France) and Lyon (France), Laboratoire of Biology of Oxidative Stress, UFR de Pharmacie. Grenoble (France).

STUDY DESIGN

Double-blind, randomized placebo-controlled intervention trial.

SUBJECTS

A total of 100 apparently healthy pregnant women were recruited at 14+/-2 weeks of gestation to delivery. At the end, they were 65 women to follow out the study.

INTERVENTIONS

Daily consumption over gestation of a micronutrients supplement or placebo.

MAIN OUTCOME MEASURES

Plasma micronutrient levels and oxidative stress parameters were measured in mothers at 14 and 38 weeks of gestation. New born's anthropometric characteristics were measured at delivery.

RESULTS

In the supplemented group, folic acid, vitamin C, E, B2, B6 and beta-carotene levels were higher than in the placebo group. Oxidative stress parameters were not different between the groups. Birth weights were increased by 10% and the number of low newborn weights (<2700 g) decreased significantly when the mother received the supplementation. Maternal plasma Zn levels were positively correlated to the newborn heights.

CONCLUSION

A regular intake of a micronutrient supplement at nutritional dose may be sufficient to improve micronutrient status of apparently healthy pregnant women and could prevent low birth weight of newborn.

Current concepts in the use of antioxidants for the treatment of preeclampsia

Preeclampsia is a leading cause of maternal and neonatal mortality and morbidity. It is a complex syndrome of undetermined etiologic origin, usually diagnosed during the second half of pregnancy, with clinical features of hypertension, proteinuria, and edema. No cure for preeclampsia exists, except premature delivery. There is increasing evidence that oxidative stress is an important contributing factor to the pathogenesis of preeclampsia. Oxidative stress is defined as an imbalance between reactive oxygen species (ROS), such as nitric oxide (NO*), superoxide anion (O2*-), and hydrogen peroxide (H2O2), and antioxidants, favouring an overabundance of ROS. The consequence of an overproduction of ROS can be observed as increased levels of markers of oxidative stress, such as lipid peroxides. Pregnant women affected by preeclampsia may have abnormal ROS production, particularly NO* and O2*-, abnormal levels of antioxidant defences, and increased placental lipid peroxidation. Several observations suggest that decreased bioavailability of endothelium-derived NO*, due to oxidative destruction of NO* by ROS, might contribute to the impaired endothelium-dependent vasodilatory responses and multisystemic pathology of preeclampsia, a phenomenon in which antioxidant vitamins may play a beneficial role. This review focuses on the rationale for vitamins C and E supplementation toward prevention of preeclampsia, with an emphasis on the limit of our scientific knowledge concerning the deleterious oxidative events taking place in this pathology.

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.

Mishandling of copper by albumin: role in redox-cycling and oxidative stress in preeclampsia plasma

OBJECTIVE

To test the hypothesis that enhanced oxidative stress during pregnancies complicated by preeclampsia is associated with improper copper (Cu) binding by plasma albumin, resulting in enhanced Cu redox-cycling activity and that altered Cu binding, in turn, is caused by interactions of excessive amounts of free fatty acids with albumin.

STUDY DESIGN

We studied binding and redox-cycling activity of Cu in 17 normal pregnancy and 17 preeclampsia plasma samples. Binding of exogenous Cu in plasma samples was quantified indirectly using spectrophotometric measurements of its complex with a specific chelator of Cu(I), bathocuproine disulfonate. Redox-cycling activity of Cu in plasma samples was estimated by electron paramagnetic resonance (EPR) spectroscopy of ascorbate radicals formed during one-electron oxidation of ascorbate by redox-active catalytic Cu. Formation of Cu/albumin complexes in model systems in the presence and absence of fatty acids was studied using EPR spectroscopy of Cu(II)/albumin.

RESULTS

We found that preeclampsia plasma (as compared to normal pregnancy plasma) (1) displays elevated endogenous ascorbate redox-cycling that is normalized by a Cu(II) chelator, cuprizone I, (2) has lowered capacity to bind and redox-regulate exogenously added Cu, and (3) responds to treatment with fatty-acid-free albumin by diminished ascorbate oxidizing activity. Conversely, addition of free fatty acid (oleic acid) to normal pregnancy plasma sample yields increased ascorbate redox-cycling activity. Our model experiments showed that Cu-dependent redox-cycling activity of purified human serum albumin is significantly increased by excess free fatty acids.

CONCLUSION

Mishandling of Cu by albumin contributes to oxidative stress in preeclampsia. Cu chelators may represent promising mechanism-based antioxidants to attenuate oxidative stress in preeclampsia.

Recent Insights into the pathogenesis of pre-eclampsia

Pre-eclampsia is more than pregnancy induced hypertension. The emerging view described in this presentation is that pre-eclampsia is secondary to the interactions of reduced placental perfusion with diverse maternal factors that alter endothelial function. The maternal contribution is from factors that antedate pregnancy and are influenced by the usual metabolic adaptations of pregnancy. The endothelium and other targets for the effects of these interactions are more sensitive to insults during pregnancy because of activation of the inflammatory cascade as a normal part of pregnancy. At least part of the response to reduced placental perfusion may be a fetal adaptive response to attempt to overcome the reduced delivery of nutrients. A reasonable convergence point for the interaction is at the level of oxidative stress. This hypothesis has both encouraging and discouraging corollaries. The diversity of maternal factors argues that there will be no single gene to explain the disorder and no single 'magic bullet' to treat the disorder. However, it is encouraging that the recognition of maternal predisposition to the disorder directs therapy to prevent pre-eclampsia at a specific target in subsets of women. Finally, the suggestion that some of the maternal alterations are due to fetal adaptive responses encourages careful choices of agents and meticulous infant follow up in well planned clinical trials.

Brain lipid peroxidation and changes of trace metals in rats following chronic manganese chloride exposure

The aim of this study was to investigate the effects of chronic, daily, 30-d administration of manganese chloride (MnCl2) to male Sprague-Dawley rats on lipid peroxidation and changes of trace elements (manganese, iron, copper, zinc) in various brain regions. Rats were intraperitoneally injected with MnCl2 (20 mg/kg) once daily for 30 consecutive days. The Mn accumulated in frontal cortex, corpus callosum, hippocampus, striatum, hypothalamus, medulla, cerebellum, and spinal cord. Malondialdehyde, an end product of lipid peroxidation, was markedly decreased in frontal cortex and cerebellum. An increased level of Cu was observed in frontal cortex, medulla, and a cerebellum. A decreased Fe level was found only in cerebellum, and a decreased Zn level was observed in hippocampus and striatum. In a second group of animals, Mn (20 mg/kg/d) and glutathione (GSH, 15 mg/kg/d) were administered ip for 30 d. In CSH-Mn-treated rats, compared to Mn-treated rats, MDA concentrations were significantly reduced in frontal cortex, medulla and cerebellum. The changes of trace elements in rat brain were similar to the Mn-treated group. We suggest that Mn is an atypical antioxidant, as well as not involved in oxidative damage in rat brain. Fe and Cu may play roles in the protective effect of Mn against lipid peroxidation in rat brain.

Oxidative stress in bacterial meningitis in humans

OBJECTIVE

To study reactive nitrogen species-mediated oxidative brain damage and antioxidant defenses in patients with acute bacterial meningitis.

METHODS

Nitrotyrosine (a widely used marker for the formation of reactive nitrogen species, such as peroxynitrite) and the lipid peroxidation product 4-hydroxynonenal were detected by immunohistochemistry in brain specimens obtained at autopsy. CSF concentrations of nitrotyrosine were quantified by ELISA. CSF and serum concentrations of ascorbic acid, uric acid, and its oxidation product allantoin were determined by high-pressure liquid chromatography.

RESULTS

Tyrosine nitration was strongly increased during meningitis. It was most evident in inflammatory cells and blood vessels in the subarachnoid space. The same cell types stained positive for the lipid peroxidation marker 4-hydroxynonenal, suggesting that reactive nitrogen species contribute to oxidative brain damage during meningitis. High CSF nitrotyrosine concentrations were associated with an unfavorable outcome according to the Glasgow Outcome Score. In the CSF, the increase of nitrotyrosine was accompanied by a depletion of the antioxidant ascorbic acid and an increased oxidation of the natural peroxynitrite scavenger uric acid to allantoin.

CONCLUSION

These findings indicate that oxidative stress due to reactive nitrogen species and altered antioxidant defenses are involved in the pathophysiology of bacterial meningitis in humans.

Oxidative stress in pre-eclampsia

BACKGROUND

The objective of this study was to test the hypothesis that maternal plasma, cord plasma and placental tissue lipid peroxidation products are increased and antioxidants are decreased in women with pre-eclampsia.

METHODS

Placenta, maternal and cord plasma were collected at delivery from 29 normal, 21 pre-eclamptic and six eclamptic women. Plasma was collected from 21 non-pregnant matched controls. The analyses were measured by HPLC and colorimetric assay.

RESULTS

Plasma maternal concentrations of uric acid, LPO, MDA, ascorbic acid, vitamin E and cholesterol were not significantly different in pre-eclampsia as compared with normal pregnancy. Plasma concentrations of ascorbic acid and vitamin E were not significantly different in normal pregnancy as compared with the non-pregnant controls. Cord plasma concentrations of MDA were significantly higher in eclampsia (1.16+/-0.26 micromol/l) as compared with normal pregnancy (0.79+/-0.05 micromol/l, p<0.02) and pre-eclampsia (0.83+/-0.05 micromol/l, p<0.05). Cord plasma concentrations of vitamin E were significantly higher in eclampsia (21.3+/-7.5 micromol/l) as compared with normal pregnancy (10.2+/-1.1 micromol/l, p<0.01) and pre-eclampsia (10.4+/-1.8 micromol/l, p<0.04). Placental concentrations of LPO, MDA and ascorbic acid were not significantly different in pre-eclampsia as compared with normal pregnancy. Plasma cord concentrations of LPO and placental concentrations of vitamin E were undetected for normal pregnant, pre-eclamptic and eclamptic women respectively. Uric acid concentrations were significantly increased in eclampsia as compared with the non-pregnant controls (p<0.0001), normal pregnant controls (p<0.0001) and pre-eclampsia (p<0.008).

CONCLUSIONS

The findings in this study do not show any evidence of deficiency in the maternal protective antioxidant systems or increased production of lipid peroxidation products, LPO and MDA in African women with pre-eclampsia as compared with normal pregnancy. However, there was evidence of increased cord plasma concentrations of MDA and vitamin E in eclampsia as compared with normal pregnancy and pre-eclampsia. The placenta may be effective in removing MDA. The antioxidant uric acid serves as a protective role whilst the antioxidant and oxidant capacity in the different study groups remained unchanged.

Elevated levels of S-nitrosoalbumin in preeclampsia plasma

The availability of nitric oxide (NO), which is required for the normal regulation of vascular tone, may be decreased in preeclampsia, thus contributing to the vascular pathogenesis of this pregnancy disorder. Because ascorbate is essential for the decomposition of S-nitrothiols and the release of NO, we speculated that the ascorbate deficiency typical of preeclampsia plasma might result in decreased rates of decomposition of S-nitrosothiols. We tested the hypothesis that total S-nitrosothiol and S-nitrosoalbumin concentrations are increased in preeclampsia plasma, reflecting a decreased release of NO from these major reservoirs of NO. Gestationally matched plasma samples were obtained (before labor or intravenous MgSO(4)) from 21 women with preeclampsia and 21 women with normal pregnancy, and plasma samples were also obtained from 12 nonpregnant women of similar age and body mass index during the follicular phase of the menstrual cycle. All were nonsmokers. The assay included ultraviolet-induced decomposition of S-nitrosothiols to liberate NO captured by a florigenic reagent, 4,5-diaminofluoresceine, to produce diaminofluoresceine-Triazole. Preeclampsia plasma contained significantly higher concentrations of total S-nitrosothiols (11.1+/-2.9 nmol/mL) than normal pregnancy samples (9.4+/-1.5 nmol/mL). Even greater differences were found between preeclampsia plasma and plasma samples from normal pregnancies and nonpregnant women (294+/-110, 186+/-25, and 151+/-25 pmol/mg protein, respectively) when S-nitrosothiol content was expressed per milligram protein. The albumin fraction contained 49.4% of total plasma S-nitrosothiols in the control samples and 53.7% and 56.8% of plasma S-nitrosothiols in normal pregnancy and preeclampsia, respectively. The level of S-nitrosoalbumin was significantly higher in preeclampsia than in normal pregnancy or nonpregnancy plasma (6.3+/-1.4, 5.1+/-0.7, and 4.2+/-1.0 nmol/mL, respectively). The increased concentration of S-nitrosoalbumin in preeclampsia almost completely accounted for the increased levels of S-nitrosothiols in total plasma. Due to combined increases in nitrosothiols and decreases in protein, the preeclampsia plasma concentration of S-nitrosoalbumin was greatly increased on a per milligram of protein basis (271% and 186% compared with normal nonpregnancy and normal pregnancy plasma, respectively). We conclude that S-nitrosoalbumin and total S-nitrosothiol concentrations are significantly increased in preeclampsia plasma and may reflect insufficient release of NO groups in this condition.

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.

Evaluation of Total Reactive Antioxidant Potential (TRAP) of Tissue Homogenates and Their Cytosols

This study evaluates the possibility of obtaining total reactive antioxidant potential (TRAP) indexes in homogenates and their cytosolic fractions by a procedure based on the quenching of luminol luminescence induced by the thermolysis of 2,2'-azo-bis(2-amidinopropane). Measurements were performed in rat brain, liver, kidney, and heart homogenates. TRAP indexes can be easily determined both in homogenates and their cytosolic fractions. The results obtained indicate that heart homogenates are the least and liver homogenates the most protected of the systems considered. Glutathione is the measured antioxidant that contributes the most to TRAP values, while uric acid makes a significant contribution only in liver. A calculation of theoretical TRAP values from the measured concentrations of the main antioxidants (glutathione, uric acid, ascorbic acid, and alpha-tocopherol) for the different homogenates shows that, in most tissues (liver, brain, and kidney), nearly 50% of the experimentally determined TRAP values are not accounted for. This difference is mainly due to the contribution of proteins to the measured TRAP.

Effect of dietary supplements containing antioxidants on attenuation of muscle damage in exercising sled dogs

OBJECTIVE

To determine whether dietary antioxidants would attenuate exercise-induced increases in plasma creatine kinase (CK) activity in sled dogs.

ANIMALS

41 trained adult sled dogs.

PROCEDURE

Dogs, randomly assigned to 2 groups, received the same base diet throughout the study. After 8 weeks on that diet, 1 group (21 dogs) received a daily supplement containing vitamins E (457 U) and C (706 mg) and beta-carotene (5.1 mg), and a control group (20 dogs) received a supplement containing minimal amounts of antioxidants. After 3 weeks, both groups performed identical endurance exercise on each of 3 days. Blood samples were collected before and 3 weeks after addition of supplements and after each day of exercise. Plasma was analyzed for vitamins E and C, retinol, uric acid, triglyceride, and cholesterol concentrations, total antioxidant status (TAS), and CK activity.

RESULTS

Feeding supplements containing antioxidants caused a significant increase in vitamin E concentration but did not change retinol or vitamin C concentrations orTAS. Exercise caused significantly higher CK activity, but did not cause a significant difference in CK activity between groups. Exercise was associated with significantly lower vitamin E, retinol, and cholesterol concentrations and TAS but significantly higher vitamin C, triglyceride, and uric acid concentrations in both groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Use of supplements containing the doses of antioxidants used here failed to attenuate exercise-induced increases in CK activity. Muscle damage in sled dogs, as measured by plasma CK activity, may be caused by a mechanism other than oxidant stress.

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.

Is the endogenous peroxyl-radical scavenging capacity of plasma protective in systemic inflammatory disorders in humans?

Systemic inflammatory response syndrome (SIRS) in humans is associated with heightened intravascular oxidative stress. The clinical significance of plasma endogenous antioxidative capability in SIRS remains undetermined. Time-sequence changes of plasma total radical-trapping antioxidant parameter (TRAP) and its components were measured in 135 patients with various clinical conditions leading to SIRS. The results were correlated with clinical parameters. Plasma TRAP significantly depressed upon diagnosis of SIRS (SIRS vs. healthy subjects (n = 50), 605.7 +/- 20.4 vs. 803.4 +/- 30.8 microM Trolox equivalent, p <.001). In survivors (n = 86), TRAP declined further during the course of SIRS, followed by a mild recovery at the end of follow-up. General linear mixed model analysis revealed that uric acid, vitamin C, vitamin E and unidentified antioxidants contributed to most of the changes in TRAP (each factor p <.001). In nonsurvivors (n = 49), TRAP increased steadily until death, and the increase was predominantly the result of the increased contribution of bilirubin (p <.01). Higher TRAP levels were not correlated with diminished blood oxidants formation (r = -0.13, p.05), lower intensity of lipid peroxidation (r = 0.261, p <.05) or lesser disease severity of SIRS. The results do not support the hypothesis that the endogenous peroxyl radical scavenging ability of plasma plays a protective role in the course of SIRS.

Low plasma antioxidant activity is associated with high lesion volume and neurological impairment in stroke

BACKGROUND AND PURPOSE

Oxidative stress is probably involved in neuronal damage induced by ischemia-reperfusion. The purpose of this study was to assess the role of antioxidant activity in cerebral ischemic stroke.

METHODS

Antioxidant activity of blood plasma and cerebrospinal fluid was assessed in 22 patients with cerebral hemisphere infarction that was verified and quantified by MRI.

RESULTS

Low total peroxyl radical trapping potential of plasma, but not of cerebrospinal fluid, was associated with high lesion volume and high neurological impairment assessed by scores on NIH Stroke Scale, Barthel Index, and Hand Motor Score tests. The plasma concentrations of ascorbic acid, alpha-tocopherol, and protein thiols were also associated with the degree of neurological impairment.

CONCLUSIONS

These data suggest that the antioxidant activity of plasma may be an important factor providing protection from neurological damage caused by stroke-associated oxidative stress.

Nitecapone as an additive to crystalloid cardioplegia in patients who had coronary artery bypass grafting

BACKGROUND

Nitecapone has been shown to have a protective effect against ischemia-reperfusion injury in experimental heart transplantation and in Langendorff preparations. This prospective, randomized study assessed the effects of nitecapone in patients who had coronary artery bypass grafting.

METHODS

Thirty patients with normal myocardial function were randomly divided into control patients (n = 15), who received crystalloid (Plegisol) cardioplegia, and nitecapone patients, who received nitecapone in a 50 microM solution (n = 15) in Plegisol. Cardioplegia was administered as an initial dose of 15 mL/kg of body mass after cross-clamping and 2 mL/kg every 15 minutes. Simultaneous coronary sinus and aortic blood samples, and myocardial biopsies were taken at 1, 5, and 10 minutes after unclamping. Hemodynamics were measured invasively for 24 hours and with transesophageal echocardiography for 3 hours after cardiopulmonary bypass.

RESULTS

There were no adverse effects. The incidence of ventricular arrhythmias was significantly lower in the treatment group during the recovery period (p = 0.02). Cardiac output and stroke volume did not differ significantly between the groups. The conjugated dienes gradient between the aorta and the coronary sinus increased significantly during the first minute of reperfusion in the control group (p = 0.02) compared with the nitecapone group. Myeloperoxidase activity in myocardial biopsies was higher in the control group (2.3 times higher at 5 minutes and 3.2 times higher at 10 minutes) than in the nitecapone group (p = 0.13).

CONCLUSIONS

Nitecapone did not exert any significant hemodynamic effects in patients with normal ejection fraction.

Effect of exercise training, selenium and vitamin E on some free radical scavengers in horses (Equus caballus)

Physical exercise increases both tissue needs for oxygen and cellular respiration and causes an overproduction of free radicals. When free radical generation exceeds the cell's antioxidant capacity tissue-damage develops due to oxidative stress. Therefore, it appears important to increase the scavenger ability of the tissues. Controlled training and dietary supplements may provide ways of doing this. As a model, we used 3-year-old racehorses (Equus caballus) which underwent a series of different physical exercise trials before and after 70 days of daily training and dietary supplements (vitamin E and selenium). The above treatments were able to increase both red blood cell resistance to the peroxidative stress induced in vitro and the glutathione peroxidase activity in lymphocytes. Moreover, they were also able to decrease malondialdehyde (MDA) concentration in the plasma as well as vitamin E consumption and the mobilisation of low molecular weight antioxidants (total peroxyl-radical trapping) following the physical exercise trials. The results obtained indicated that the training and diet supplements we used were able to significantly increase horse antioxidant defences in both the extracellular fluids and blood cells of our horses, thus decreasing peroxidative phenomena following physical exercise.

Association between oxidative stress and changes of trace elements in patients with breast cancer

OBJECTIVES

To investigate the association between oxidative stress and certain trace elements in the blood of breast cancer patients.

DESIGN AND METHODS

Malondialdehyde (MDA) was measured in serum of patients with breast cancer (n = 35) and controls (n = 35) by high performance liquid chromatography. Trace elements were determined by atomic absorption spectrophotometry.

RESULTS

In the present study, significantly increased lipid peroxidation, measured as MDA, was demonstrated in the serum of breast cancer patients (p < 0.01). The concentrations of zinc and iron remained unaltered. However, the mean serum copper level in patients with breast cancer was significantly higher than the control group (p < 0.01). In addition, the mean serum selenium level in patients with stage III was significantly lower than the control group (p < 0.05). Moreover, a positive correlation was also observed between copper and MDA levels in the patient group but not in the control group.

CONCLUSION

In the present study, the presence of an association between oxidative stress and trace elements was observed in patients with breast cancer. We suggest that increased oxidative stress in patients with breast cancer may result from changes in the levels of certain trace elements.

Plasma chain-breaking antioxidants in preterm infants with good and poor short-term outcome

Many complications of prematurity have been suggested to result from free radical generation and an inadequacy of antioxidative capacity. We measured the plasma total peroxyl radical-trapping capability (TRAP) and concentrations of the main chain-breaking antioxidants contributing to it, i.e. uric acid, ascorbic acid, alpha-tocopherol, protein sulfhydryl groups and bilirubin, in 21 preterm infants with a mean birth weight of 1440 g and gestational age of 30 wk. The infants were divided into two groups according to their short-term outcome; the good outcome group (GOG) (N = 11) with no signs of morbidity and the poor outcome group (POG) (N = 10) with intraventricular haemorrhage and/or bronchopulmonary dysplasia and/or retinopathy. Arterial blood samples were obtained 3 and 10 days postpartum. TRAP was measured with a chemiluminescent method. As a comparison, venous blood samples from 13 adults (aged from 18 to 34) were used. At day 3 the poor outcome group had significantly higher TRAP than the good outcome or control group, mainly because of elevated uric acid concentration. Also the concentration of unidentified antioxidants was significantly lower in GOG. By day 10 the TRAP decreased substantially in both groups. However, from the components of TRAP, both ascorbate and the unidentified fraction decreased more in POG (p = 0.017 and 0.021, respectively). Furthermore in POG on day 10 urate concentration did not significantly differ from day 3 values. In conclusion, in preterm infants high TRAP was associated with high plasma uric acid concentration and a poor short-term prognosis.

The Effect of Nitecapone, a New Antioxidant, on Myocardial Function After Aortic Cross-clamping in Experimental Heart Ischemia

During aortic cross-clamping, the myocardium suffers from global ischemia, which is followed by reperfusion after declamping. The generation of free oxygen radicals increases during reperfusion, resulting in arrhythmias and impaired cardiac function. This study was conducted to evaluate the effect of a novel antioxidant nitecapone (NC) on cardiac reperfusion injury in vivo. Twelve pigs were anesthetized and after sternotomy the aorta and the right atrium were cannulated for cardiopulmonary bypass. The heart was arrested with either +4 degreesC crystalloid cardioplegia alone in the control group (n = 6) or cardioplegia with NC (50 µM) added in the NC group (n = 6). Cardioplegia was added every 20 minutes. After 1 hour of aortic cross-clamping, blood samples for oxidative stress analysis were taken, and hemodynamic profile surveillance continued for 90 minutes. Heart rate (p = 0.04) and left ventricular end diastolic pressure (LVEDP) (p = 0.04) were significantly lower in the NC group than in the C group after aortic declamping. Cardiac output and myocardial contractility (dP/dtmax) were also enhanced in the group receiving NC, but the difference was not statistically significant. At 30 minutes after reperfusion, the coronary production (coronary sinus-aorta) of thiobarbituric acid reactive substances correlated inversely with cardiac output (r = -0.90, p = 0.001) and stroke volume (r = -0.82, p = 0.007). The effect of NC on lipid peroxidation seems to be modest and therefore the target of NC is unclear. NC would appear, however, to be a beneficial additive in the crystalloid cardioplegia in terms of functional recovery.

Etiology and pathogenesis of preeclampsia: current concepts

The etiology of preeclampsia is unknown. At present, 4 hypotheses are the subject of extensive investigation, as follows: (1) Placental ischemia-Increased trophoblast deportation, as a consequence of ischemia, may inflict endothelial cell dysfunction. (2) Very low-density lipoprotein versus toxicity-preventing activity-In compensation for increased energy demand during pregnancy, nonesterified fatty acids are mobilized. In women with low albumin concentrations, transporting extra nonesterified fatty acids from adipose tissues to the liver is likely to reduce albumin's antitoxic activity to a point at which very-low density lipoprotein toxicity is expressed. (3) Immune maladaptation-Interaction between decidual leukocytes and invading cytotrophoblast cells is essential for normal trophoblast invasion and development. Immune maladaptation may cause shallow invasion of spiral arteries by endovascular cytotrophoblast cells and endothelial cell dysfunction mediated by an increased decidual release of cytokines, proteolytic enzymes, and free radical species. (4) Genetic imprinting-Development of preeclampsia-eclampsia may be based on a single recessive gene or a dominant gene with incomplete penetrance. Penetrance may be dependent on fetal genotype. The possibility of genetic imprinting should be considered in future genetic investigations of preeclampsia.

The association between the total antioxidant potential of plasma and the presence of coronary heart disease and renal dysfunction in patients with NIDDM

Oxidative stress may be an important pathogenetic factor in the development of diabetic vascular complications. The total antioxidative potential of plasma reflects the ability of an individual to resist oxidative stress. We measured the plasma total peroxyl radical-trapping potential (TRAP) and the concentrations of four plasma chain-breaking antioxidants in 81 patients with non-insulin-dependent diabetes mellitus (NIDDM) nine years after diagnosis and in 102 well-matched non-diabetic control subjects. The association between the total antioxidative potential and the presence of coronary heart disease (CHD) and diabetic kidney disease were also studied. There were no significant differences in plasma TRAP between NIDDM patients and control subjects (1250+/-199 vs. 1224+/-198 microM). Nor were there any significant differences in the concentrations of plasma uric acid, ascorbic acid, alpha-tocopherol, and protein thiols between NIDDM patients and control subjects. Patients with a low glomerular filtration rate and/or high urinary albumin excretion had elevated plasma uric acid. Plasma TRAP was not, however, associated with renal dysfunction. The plasma of NIDDM patients with CHD had a significantly higher value of unidentified antioxidative potential than that of patients without CHD. This relation was strongly dependent upon smoking. In conclusion, these data demonstrate that there are no major defects in the antioxidative potential of plasma caused by NIDDM per se. CHD and diabetic renal dysfunction were not associated with changes in plasma TRAP.

Unaltered antioxidant activity of plasma in subjects at increased risk for IDDM

Evidence suggests that free oxygen radicals are involved in the destruction of islet beta-cells in insulin-dependent diabetes mellitus (IDDM). Therefore, we determined the plasma antioxidant activity in 51 healthy unaffected children and adolescents randomly chosen from a study of beta-cell autoimmunity in schoolchildren in northern Finland. Twenty-two subjects tested positive for one or more IDDM-associated autoantibodies and 9 subjects had at least two of the three antibodies tested (antibodies against islet cells, ICA; glutamic acid decarboxylase, GADA; insulin, IAA). There was no significant association of total plasma antioxidant potential, plasma concentrations of alpha-tocopherol, ascorbic acid, protein thiols, or uric acid with the presence of ICA, GADA, or IAA. A reduced first-phase insulin response to intravenous glucose was also not associated with reduced plasma antioxidant activity. These results indicate that the plasma antioxidant activity is not decreased in subjects at increased risk for IDDM. Furthermore, the results suggest that the clinical onset of IDDM is not preceded by signs of increased systemic oxidative stress in plasma.

Total antioxidant capacity of serum increased in early but not late period after intestinal ischemia in rats

The ischemia of small intestine was induced in anesthetized Wistar rats by occluding the superior mesenteric artery for 45 min and then the reperfusion was set. Serum samples were obtained at the end of the ischemic period and also during early (1 to 4 h) and late postischemic period (1 to 4 d). The total antioxidant capacity (TRAP) of serum samples was evaluated using luminol enhanced chemiluminescence. The increased mobilization of phagocytic cells and the release of reactive oxygen species into the circulation was observed from the first and second hour of the postischemic period, respectively. Nevertheless, the activity of natural antioxidant mechanisms of serum was already elicited at the end of the ischemic period. Furthermore, the TRAP of serum increased with the increasing duration of early postischemic period. Among the antioxidants studied, urate and ascorbate concentrations exerted the highest correlation with TRAP, but 31.6% of the total antioxidant capacity remained for the activity of an unidentified antioxidant(s). After being exhausted, the TRAP of serum oscillated around the preoperation level at days 1-4 of the postischemic period. The increase in total antioxidant capacity of serum induced by oxidative stress was sufficient to prevent lipoperoxidation both in serum and intestinal tissue.

Phagocyte-induced oxidative stress in patients with haemodialysis treatment and organ transplantation

The aim of the study was to examine the phagocyte-derived production of reactive oxygen species (ROS), lipoperoxidation and the total radical-trapping antioxidant parameter (TRAP) in patients undergoing regular haemodialysis (HD) followed by kidney transplantation (n = 13). A significant increase in both spontaneous and activated ROS generation was found during the post-transplantation period in days 1-3. This effect was caused mainly by an increased number of neutrophils. On the other hand, the TRAP parameter was decreased in HD patients. After kidney transplantation, the TRAP parameter increased, reaching the level of healthy controls at the end of the first week after surgery. Increase in MDA level was determined after HD and kidney transplantation. It can be concluded from the results obtained that phagocyte mobilisation and increased oxidative stress after HD and kidney transplantation were associated with the insufficient activity of extracellular antioxidant mechanisms resulting in increased lipid peroxidation.

Leukocyte mobilization, chemiluminescence response, and antioxidative capacity of the blood in intestinal ischemia and reperfusion

Intestinal ischemia and reperfusion elicits changes in leukocyte counts and increased production of reactive oxygen species (ROS). The purpose of this study was to investigate whether these changes were followed by and/or connected with changes in the extracellular antioxidative capacity in a rat superior mesenteric artery (SMA) occlusion/reperfusion model. The SMA was occluded for 45 min and then allowed to be reperfused. Changes of leukocyte, polymorphonuclear (PMN), and lymphocyte counts, chemiluminescence (CL) of whole blood samples as a marker of ROS production, and the total antioxidative capacity of the serum were quantified at the end of ischemia and in 1 h intervals during the postischemic period up to 4 h. The myeloperoxidase (MPO) activity in the serum and intestinal tissue samples was also determined. The MPO activity in the intestinal tissue samples was significantly elevated at the end of ischemia, and this elevation lasted for the whole postischemic period. The oxidative challenge to the body induced a fast mobilization of extracellular antioxidative mechanisms already at the end of ischemia, which was followed by a significant increase in PMN counts and whole blood CL starting at the 2nd hour after reperfusion. The increased CL activity of whole blood was attributed to the increase of the circulating PMNs. No significant changes were observed in leukocyte and lymphocyte counts. It is concluded that compensatory mechanisms of the oxidative-antioxidative balance of the body react very quickly if challenged.

Plasma peroxyl radical trapping capacity in lung cancer patients: a case-control study

Increasing evidence suggests that cancer patients express oxidative disturbances. The main objective of this cross-sectional case-control study (n = 57 + 76) was to explore whether lung cancer patients, when compared to healthy controls, have alterations in their plasma peroxyl radical trapping capacity (TRAP). Group matching was used with respect to age, sex and smoking history. A secondary objective was to observe the effects of life-long cigarette consumption on plasma TRAP and its components. Mean TRAP values were significantly lower in the cancer patients than in the control group (1143 vs 1273 mumol/l, p = 0.0002). Moreover, all the components of TRAP (except uric acid) were significantly lower in the cancer group: protein SH-groups 442 vs 571 mumol/l, ascorbic acid 34.0 vs 46.5 mumol/l and vitamin E 25.0 vs 33.8 mumol/l. The as yet unidentified antioxidant compounds in plasma contributed 26.5% of plasma TRAP in the cancer group and 30.2% in the control group. There was no correlation between cigarette consumption in pack-years and plasma TRAP; however, plasma concentrations of uric acid and ascorbic acid were negatively correlated with cigarette consumption.

Ascorbate and urate are the strongest determinants of plasma antioxidative capacity and serum lipid resistance to oxidation in Finnish men

Copper-induced plasma lipoprotein oxidation resistance has usually been determined in separated low density lipoprotein (LDL) fractions, that do not contain water-soluble antioxidants present in blood plasma. The aim of this study was to find the main determinants of the measurements of copper-induced lipid oxidation resistance (lag time) in whole serum and plasma total peroxyl radical trapping capacity (TRAP) in a population sample of smoking (n = 25) or non-smoking (n = 26) middle aged men at high risk of cardiovascular diseases. Smokers had significantly lower plasma ascorbic acid values, but only slightly lower alpha-tocopherol, beta-carotene and serum urate values than non-smokers. Plasma ascorbic acid concentration explained 23.5% of the lag time variation (standardized regression coefficient beta = 0.48; P = 0.004) in smokers and 5.6% in non-smokers. Serum urate concentration was the strongest determinant of lag time in non-smokers (beta = 0.64, P < 0.001). In addition, serum albumin, lipid standardized alpha-tocopherol and serum high density lipoprotein (HDL) cholesterol entered the multivariate regression mode for lag time. For plasma TRAP, only urate and ascorbic acid entered the multivariate regression model. Lag times in serum and in isolated very low density lipoprotein (VLDL) and LDL fraction did not correlate, but the maximal rate of these reactions correlated significantly. These results confirm that lipid peroxidation resistance in serum or plasma are associated with ascorbic acid, urate, alpha-tocopherol, albumin and HDL concentrations. The measurement of lipid oxidation resistance in whole serum might be more physiological than in isolated lipoprotein fraction, as the effects of water-soluble antioxidants are not artificially removed.

Unidentified antioxidant defences of human plasma in immobilized patients: a possible relation to basic metabolic rate

Plasma total peroxyl radical scavenging capacity was studied in terminal patients who were chronically immobilized because of an acute (stroke) or chronic neurodegenerative disease (Alzheimer's disease). A luminometric assay was used to measure total antioxidant capacity (TRAP). The immobilized patients showed significant decrease in TRAP primarily because of a decrease in the concentration of unknown antioxidants. Our results suggest that human plasma may contain unknown antioxidants, the regulation of which could be related to the basic metabolic rate.