Plasma F2-isoprostanes are elevated in newborns and inversely correlated to gestational age

The physiological behaviour of IMR-32 neuroblastoma cells is affected by a 12-h hypoxia/24-h reoxygenation period

Nervous system cells are highly dependent on adequate tissue oxygenation and are very susceptible to hypoxia, which causes mitochondrial dysfunctions involved in apoptosis and necrosis. In this paper, we examine the effect of a 12-h incubation of differentiated IMR-32 neuroblastoma cells in a hypoxic environment (73% N(2): 2% O(2): 5% CO(2), v:v) by evaluating cell viability, modifications of NO, intracellular Ca(2+) concentration [Ca(2+)](i) and membrane potential, the production of phosphorylated ERK, desferoxamine-chelatable free iron and esterified F2-isoprostane levels. The same parameters were evaluated after a subsequent 24-h re-oxygenation period. The NO concentration increased significantly immediately after hypoxia and returned to values similar to those of controls after the reoxygenation period. At the same time, we observed a significant increase of [Ca(2+)](i) immediately after hypoxia. Phosphorylated ERK proteins increased significantly during the first 2 h of hypoxia, then decreased, and remained practically unmodified after 12 h hypoxia and the following reoxygenation period. Moreover, IMR-32 cell mitochondria were significantly depolarized after hypoxia, while membrane potential returned to normal after the reoxygenation period. Finally, desferoxamine-chelatable free iron and F2-isoprostane levels also increased significantly after hypoxia. Our results indicate that 2% O(2) hypoxia induces variations of NO and [Ca(2+)](i) with subsequent mitochondrial depolarization, and it is responsible for oxidative stress, represented by increased free iron and F2-isoprostane, protein carbonyls and 4 hydroxynonenal protein adducts levels.

Isoprostanes 8-iPF2alpha-III: risk markers of premature rupture of fetal membranes?

AIMS

Isoprostanes may serve as sensitive and specific markers of in vivo oxidative stress intensity. We wanted to determine, whether or not isoprostane concentration may be considered as a risk marker of premature rupture of fetal membranes (PROM).

METHODS

On the basis of the presence of PROM and gestational maturity, a total of 128 patients were divided into: (1) preterm PROM (pPROM) group; (2) PROM at term group; (3) control preterm (C1) group and (4) control at term (C2) group. The concentrations of 8-iPF(2alpha)-III were determined using the enzyme-linked immunosorbent assay method.

RESULTS

The mean free isoprostane concentrations, examined in amniotic fluid and maternal plasma in the PROM at term patients were significantly higher than in C2 individuals (p < 0.01). The mean concentrations of free 8-iPF(2alpha)-III measured in blood plasma from women in the C1 group were significantly lower than in patients from the pPROM, PROM at term and C2 groups (p < 0.001, p < 0.00001 and p < 0.00001, respectively).

CONCLUSION

The measurement of free isoprostane concentration in maternal plasma and amniotic fluid may be considered as a laboratory marker of a PROM-risk pregnancy.

Antenatal steroids and antioxidant enzyme activity in preterm infants: influence of gender and timing

Antenatal steroids have improved the survival of preterm infants; however, the mechanism of action is not fully understood. We aimed to establish an association between antenatal steroids and antioxidant activity and postnatal oxidative stress. In a prospective cohort study, extremely preterm neonates receiving antenatal steroids (CORT) or not (NOCORT) were enrolled. An association between antenatal steroids and activities of antioxidant enzymes and glutathione cycle enzymes in cord blood was found. In addition, reduced oxidative stress (GSH/GSSG ratio, CORT vs. NOCORT, 35.68 + or - 12.20 vs. 28.38 + or - 9.92; p < 0.01) and, decreased oxidation of proteins (ortho-tyrosine/phenylalanine ratio, CORT vs. NOCORT, 8.66 + or - 2.45 vs. 12.55 + or - 4.41; p < 0.01) and DNA (8oxodG/2dG ratio, CORT vs. NOCORT, 6.73 + or - 2.18 vs. 9.53 + or - 3.83; p < 0.01) also was found. Antenatal steroids were associated with reduced oxygen supplementation, mechanical ventilation, and conditions such as bronchopulmonary dysplasia, intra-periventricular hemorrhage, or retinopathy of prematurity. The maximal effectiveness was when steroids were administered 2-4 days before delivery. Female preterm infants had less oxidative stress and increased antioxidant activity and better clinical outcomes than did male infants, independent of receiving or not antenatal steroids. Antenatal steroids are accompanied by a reduction in postnatal oxidative-stress-derived conditions and increased antioxidant enzyme activity. Both these effects seem to be influenced by specific timing and female gender.

F2-isoprostanes and total radical-trapping antioxidant potential in preterm infants receiving parenteral lipid emulsions

OBJECTIVE

We assessed the effects of three different parenteral lipid emulsions (long-chain triacylglycerols, medium-chain/long-chain triacylglycerols, olive oil) on lipid peroxidation in preterm infants. The hypothesis to be tested was that preterm infants receiving the olive oil-based lipid emulsion would undergo less peroxidation than preterm infants receiving lipid emulsions based on long- or medium-chain triacylglycerols. The secondary aim was to evaluate whether the lipid peroxidation persists beyond the cessation of parenteral nutrition (PN).

METHODS

A randomized controlled trial was designed. Thirty-six consecutive preterm infants (gestational age 28-33 wk) were enrolled in the study. Preterm infants were randomized to receive one of the three emulsions within the first 24h of life. Plasma F2-isoprostanes (F2-Ip) and total radical-trapping antioxidant potential (TRAP) were determined at baseline, on day 7 of PN, and on day 7 after stopping PN.

RESULTS

The F2-Ip and TRAP concentrations were not statistically different within and among the three groups at any time of the study. No significant interaction effect between the type of lipid emulsion administered and the repeated values of F2-Ip and TRAP was found. F2-Ip values showed a trend to decrease throughout the study in all the three groups.

CONCLUSION

No significant difference in oxidative stress of preterm infants was detected according to the type of lipid emulsion received.

Effects of 50 Hz electromagnetic fields on rat cortical synaptosomes

Nerve cells are very responsive to weak pulsed electromagnetic fields (EMFs). Such non-ionizing radiation, with frequencies of 0-300 Hz and 0.1-100 mT, can affect several cellular activities, with unusual dose-response characteristics. The present study examined the effect of a 2-h exposure of synaptosomes on a system generating a peak magnetic field of 2 mT. We evaluated the changes of the synaptosomal mitochondrial respiration rate and ATP production, membrane potential, intrasynaptosomal Ca2+ concentration, and the release of free iron and F2-isoprostanes. O2 consumption and ATP production remained unchanged in exposed synaptosomes. The intrasynaptosomal Ca2+ concentration decreased slowly and no depolarization of the synaptosomal membrane was detected. Finally, the release of free iron and F2-isoprostanes by synaptosomal suspensions also remained unchanged after EMF exposure. These results indicate that the physiological behavior of cortical synaptosomes was unaffected by weak pulsed EMFs.

Profiling of oxidative stress in patients with inborn errors of metabolism

Free radical formation resulting in oxidative stress is a hallmark of mitochondrial dysfunction. Indeed, oxidative stress has been demonstrated to be an underlying pathophysiologic process in various inborn errors of metabolism. Metabolic profiling of oxidative stress may provide a non-specific measure of disease activity that may further enable physicians to monitor disease. In the present study, we investigated two markers of oxidative damage in urinary samples from IEM subjects and controls: F-2 isoprostanes, a measure of lipid peroxidation and di-tyrosine, a measure of protein oxidation. We also determined urinary antioxidant activity in these samples. Subsets of IEM patients showed significantly higher levels of the damage markers isoprostanes and di-tyrosine. Of note, patients with cobalamin disorders (i.e., CblB and CblC) consistently had the highest levels of oxidative damage markers. Lower urine antioxidant capacity was seen in all subject categories, particularly cobalamin disorders and propionic acidemia. Longitudinal studies in subjects with MSUD showed good concordance between markers of oxidative damage and acute decompensation. Overall, quantifying oxidative stress offers a unique perspective to IEM. These measures may provide a means of addressing mitochondrial function in IEM and aid in the development of therapeutic targets and clinical monitoring in this diverse set of disorders.

Systemic oxidative stress in classic Rett syndrome

Rett syndrome (RS), a progressive severe neurodevelopmental disorder mainly caused by de novo mutations in the X-chromosomal MeCP2 gene encoding the transcriptional regulator methyl-CpG-binding protein 2, is a leading cause of mental retardation with autistic features in females. However, its pathogenesis remains incompletely understood, and no effective therapy is available to date. We hypothesized that a systemic oxidative stress may play a key role in the pathogenesis of classic RS. Patients with classic RS (n=59) and control subjects (n=43) were evaluated. Oxidative stress markers included intraerythrocyte non-protein-bound iron (NPBI; i.e., free iron), plasma NPBI, F2-isoprostanes (F2-IsoPs, as free, esterified, and total forms), and protein carbonyls. Lung ventilation/perfusion (V/Q) ratio was assessed using a portable gas analyzer, and RS clinical severity was evaluated using standard scales. Significantly increased intraerythrocyte NPBI (2.73-fold), plasma NPBI (x 6.0), free F(2)-IsoP (x1.85), esterified F2-IsoP (x 1.69), total F2-IsoP (x 1.66), and protein carbonyl (x 4.76) concentrations were evident in RS subjects and associated with reduced (-10.53%) arterial oxygen levels compared to controls. Biochemical evidence of oxidative stress was related to clinical phenotype severity and lower peripheral and arterial oxygen levels. Pulmonary V/Q mismatch was found in the majority of the RS population. These data identify hypoxia-induced oxidative stress as a key factor in the pathogenesis of classic RS and suggest new therapeutic approaches based on oxidative stress modulation.

Long-term impact of an antioxidant-deficient neonatal diet on lipid and glucose metabolism

Newborn infants are at risk for oxidative stress leading to metabolic syndrome features. Oxidative stress can be induced by oxidant load such as oxygen supplementation, peroxides from intravenous nutrition, or low antioxidant defenses. We hypothesize that a modulation of antioxidant defenses during the neonatal period, without external oxidant challenge, will have a long-term influence on energy metabolism. Guinea pigs were fed between their third and their seventh day of life a regular chow leading to "mature" antioxidant defenses or a deficient chow leading to lower antioxidant defenses. Between weeks 1 and 14, the animals were fed regular chow. The hepatic oxidized redox status of glutathione associated with the deficient diet (-221 +/- 2 vs -228 +/- 1 mV, p < 0.01) was maintained until 14 weeks. At 13-14 weeks, animals fed the deficient diet presented lower plasma TG (479 +/- 57 vs 853 +/- 32 microM, p < 0.01), lower blood glucose (5.8 +/- 0.3 vs 6.9 +/- 0.3 mM, p < 0.05), and better tolerance to glucose (p < 0.05). Blood glucose correlated negatively with the redox status (r2 = 0.47, p < 0.01). Low antioxidant defenses during the neonatal period induce a better energy substrate profile associated with an oxidized redox status later in life. These findings suggest being aware of negative consequences when adopting "aggressive" antioxidant therapies in newborn infants.

The effects of hypoxia/reoxygenation on the physiological behaviour of U373-MG astrocytes

Nerve cells are very susceptible to hypoxia responsive for mitochondrial dysfunctions involved in the subsequent oxidative stress, apoptosis and necrosis. In this paper, we examined the effect of 12 h incubation of U-373 MG astrocytes in hypoxic environment (73% N(2): 2% O(2): 5% CO(2), v:v) by evaluating cell proliferation, modifications of NO and ATP production, intracellular Ca(2+) concentration [Ca(2+)](i), membrane potential, desferoxamine-chelatable free iron, esterified F2-isoprostanes levels and the production of phosphorylated ERK. The same parameters were evaluated also after a following re-oxygenation period of 24 h. Immediately after hypoxia the NO concentration increased significantly and returned to values similar to those of controls after the re-oxygenation period. At the same time, ATP levels remained similar to controls and the cell proliferation significantly decreased. This involved a significant increase of [Ca(2+)](i) immediately after hypoxia and the value remained significantly elevated after the following re-oxygenation period. Moreover, after hypoxia, astrocytes were slightly although not significantly depolarized. Indeed iron and F2-isoprostanes levels increased significantly after hypoxia. Finally ERK proteins increased slowly and not significantly after hypoxia and the same trend was observed after the re-oxygenation period. On the whole, our results indicate that 2% O(2) hypoxia induces a moderate oxidative stress, well tolerated by U-373 MG cells, remaining the ATP production, mitochondrial membrane potential and activated ERK proteins, similar to the values of controls.

Urinary excretion rates of 8-oxoGua and 8-oxodG and antioxidant vitamins level as a measure of oxidative status in healthy, full-term newborns

The aim of the present study was to evaluate the oxidative status in healthy full-term children and piglets. Urinary excretion of 8-oxoGua (8-oxoguanine) and 8-oxodG (8-oxo-2'-deoxyguanosine) were determined using HPLC/GS/MS methodology and concentrations of vitamins A, C and E with HPLC technique. The levels of 8-oxoGua in urine samples were about 7-8 times higher in newborn children and piglets when compared with the level of adult subjects, while in the case of 8-oxodG the difference was about 2.5 times. The levels of vitamin C and E in umbilical cord blood of newborn children significantly depend on the concentration of these compounds in their mother's blood. However, the values of vitamin C in human's cord blood were about 2-times higher than in respective mother blood, while the level of vitamin E showed an opposite trend. The results suggest that: (i) healthy, full-term newborns are under potential oxidative stress; (ii) urinary excretion of 8-oxoGua and 8-oxodG may be a good marker of oxidative stress in newborns; and (iii) antioxidant vitamins, especially vitamin C, play an important role in protecting newborns against oxidative stress.

Biomarkers of exposure to tobacco smoke and environmental pollutants in mothers and their transplacental transfer to the foetus. Part II. Oxidative damage

Oxidative damage to macromolecules may have numerous negative health consequences. We measured oxidative damage to DNA, proteins and lipids in 80 newborns and 79 mothers, analyzed the effect of mother's tobacco smoke exposure on oxidative stress, and assessed correlations between oxidative stress markers and bulky and PAH (polycyclic aromatic hydrocarbons)-specific DNA adducts. Mean levels (+/-S.D.) of 8-oxodeoxyguanosine (8-oxodG) per 10(5) dG in the placenta were 2.85+/-0.78; we did not see a difference between 8-oxodG levels in newborns born to mothers exposed and unexposed to tobacco smoke. Protein carbonyl levels, a marker of protein oxidation, were comparable in the umbilical cord and in maternal venous blood plasma (17.4+/-3.2 and 17.6+/-4.2nmol/ml plasma in newborns and mothers, respectively, p=0.66). Lipid peroxidation measured as levels of 15-F(2t)-isoprostane (15-F(2t)-IsoP) in plasma was significantly higher in newborns than in mothers (362+/-129 and 252+/-130pg/ml in newborns and mothers, respectively, p<0.001). We did not find any effect of tobacco smoke exposure on either biomarker in any group. Levels of both protein carbonyls and 15-F(2t)-IsoP in cord blood significantly correlated with those in maternal plasma (p<0.001). 8-oxodG levels positively correlated with plasma carbonyls in cord plasma, as well as with cotinine levels (marker of tobacco smoke exposure) in maternal plasma. 8-oxodG levels also correlated with bulky DNA adducts in lymphocyte DNA of newborns and mothers and with PAH-DNA adducts in the placenta. Our results showed higher lipid peroxidation in newborns than in mothers, close correlation of analyzed oxidative stress markers between newborns and mothers, and a relationship between oxidative stress and induction of DNA adducts.

Free iron, total F-isoprostanes and total F-neuroprostanes in a model of neonatal hypoxic-ischemic encephalopathy: neuroprotective effect of melatonin

Oxidative stress due to free radical formation and initiation of abnormal oxidative reactions is involved in several diseases of newborns, such as hypoxic-ischemic encephalopathy. Melatonin, an endogenously produced indoleamine primarily formed in the pineal gland, is a potent free radical scavenger as well as an indirect antioxidant. The present study was conducted to evaluate the formation of oxidative damage mediators and the possible effect of melatonin treatment in a model of hypoxic-ischemic encephalopathy in 7-day-old rats. Pups were subjected to permanent ligation of the right common carotid artery and exposed for 2.5 hr to a nitrogen-oxygen mixture (92% and 8%, respectively) (hypoxia-ischemia, HI). Melatonin was injected intraperitoneally to a group of rats at the dose of 15 mg/kg 30 min before starting the ischemic procedure (HI-Melatonin). After 24 hr of treatment, in homogenized cerebral cortex, desferoxamine (DFO)-chelatable free iron, total F(2)-isoprostanes and total F(4)-neuroprostanes, originating from the free radical-catalyzed peroxidation of arachidonic and docosahexaenoic acids, respectively, were determined. HI induced a significant increase in DFO-chelatable iron, total F(2)-isoprostanes and F(4)-neuroprostanes in both right and left side of the cerebral cortex. In HI-Melatonin-treated animals the levels of free iron, F(2)-isoprostanes, and F(4)-neuroprostanes were significantly lower than that in HI rats and the values were similar to controls. These data show the important neuroprotective role of melatonin in reducing oxidative damage resulting from HI. Melatonin could represent a potential safe approach to perinatal brain damage in humans.

Plasma esterified F2-isoprostanes and oxidative stress in newborns: role of nonprotein-bound iron

Nonprotein-bound iron (NPBI) and F2-isoprostanes, reliable markers of oxidative stress, are increased in plasma of newborns and inversely correlated to the gestational age. Because NPBI represents a pro-oxidant stimulus in plasma, we test the hypothesis that the entity of lipid peroxidation is related with NPBI concentrations. Plasma levels of free, esterified, and total F2-isoprostanes were investigated in relation to NPBI levels in 59 newborns and 16 healthy adults. The pro-oxidant role of iron was ascertained in vitro, by measuring all the forms of F2-isoprostanes after incubation with ammonium iron sulfate. Significant positive correlations were found between NPBI and total as well as esterified F2-isoprostanes in plasma of the newborns. The addition of ammonium iron sulfate induced a marked increase in all the forms of F2-isoprostanes after 2 hours of incubation. The higher NPBI concentration, the higher F2-isoprostanes levels. An increase NPBI dose dependent in total F2-isoprostanes formation was observed in dialyzed low density lipoprotein from adult plasma. The results clearly show that once NPBI is generated, whatever its source, it is capable of inducing oxidative stress. NPBI-induced oxidative stress may contribute to the morbidity in preterm infants that are particularly susceptible to free radical damage.

F2-isoprostanes are not just markers of oxidative stress

F(2)-isoprostanes are not just markers of oxidative stress. The discovery of F(2)-isoprostanes (F(2)-IsoPs) as specific and reliable markers of oxidative stress in vivo is briefly summarized here. F(2)-IsoPs are also agonists of important biological effects, such as the vasoconstriction of renal glomerular arterioles, the retinal vessel, and the brain microcirculature. In addition to the F(2)-IsoPs, E(2)- and D(2)-IsoPs can be formed by rearrangement of H(2)-IsoP endoperoxides and can give rise to cyclopentenone IsoPs, which are very reactive alpha,beta-unsaturated aldehydes. The same type of reactivity is also shown by acyclic gamma-ketoaldehydes formed as products of the IsoP pathway. Because previous studies suggested a relation between oxidative stress and collagen hyperproduction, it was investigated whether collagen synthesis is induced by F(2)-IsoPs, the most proximal products of lipid peroxidation. In contrast to aldehydes, F(2)-IsoPs act through receptors able to elicit definite signal transduction pathways. In a rat model of carbon tetrachloride-induced hepatic fibrosis, plasma F(2)-IsoPs were markedly elevated for the entire experimental period; hepatic collagen content was also increased. When hepatic stellate cells from normal liver were cultured up to activation (expression of smooth muscle alpha-actin) and then treated with F(2)-IsoPs in the concentration range found in the in vivo studies (10(-9) to 10(-8) M), a striking increase in DNA synthesis, cell proliferation, and collagen synthesis was observed. Total collagen content was similarly increased. All these stimulatory effects were reversed by the specific antagonist of the thromboxane A(2) receptor, SQ 29 548, whereas the receptor agonist, I-BOP, also had a stimulatory effect. Therefore F(2)-IsoPs generated by lipid peroxidation in hepatocytes may mediate hepatic stellate cell proliferation and collagen hyperproduction seen in hepatic fibrosis.

Isoprostanes and hepatic fibrosis

After a brief introduction to oxidative stress, the discovery of F(2)-isoprostanes as specific and reliable markers of oxidative stress is described. Isoprostanes are also agonists of important biological effects. Since a relation between oxidative stress and collagen hyperproduction has been previously suggested and since lipid peroxidation products have been proposed as possible mediators of liver fibrosis, we investigated whether collagen synthesis is induced by F(2)-isoprostanes the most proximal products of lipid peroxidation. In a rat model of carbon tetrachloride-induced hepatic fibrosis, plasma isoprostanes were markedly elevated for the entire experimental period; hepatic collagen content was also increased. When hepatic stellate cells from normal liver were cultured up to activation (expression of alpha-smooth muscle-alpha actin) and then treated with F(2)-isoprostanes in the concentration range found in the in vivo studies (10(-9)-10(-8)M), a striking increase in DNA synthesis, in cell proliferation and in collagen synthesis was observed. Moreover, F(2)-isoprostanes increased the production of transforming growth factor-beta1 by U937 cells, assumed as a model of Kupffer cells or liver macrophages. The data suggest the possibility that F(2)-isoprostanes generated by lipid peroxidation in hepatocytes mediate hepatic stellate cell proliferation and collagen hyperproduction seen in hepatic fibrosis.

Plasma levels of 15-F(2t)-isoprostane in newborn infants are affected by mode of delivery

OBJECTIVE

To investigate how the mode of delivery affects the level oxidative stress in newborns.

DESIGN AND METHODS

15-F(2t)-isoprostane, as index of oxidative stress, was measured in umbilical cord plasma samples from 37 infants born after vaginal delivery or caesarian section, using specific immuno-affinity extraction and immunoassay.

RESULTS

15-F(2t)-isoprostane levels were higher in infants born after vaginal delivery (n=18) compared to those delivered by elective caesarian section (n=19).

CONCLUSIONS

15-F(2t)-isoprostane is a sensitive biomarker of fetal oxidative stress during labor.

Anti-oxidant strategies

Oxidative stress plays an important role in causing organ injury in the compromised fetus and neonate. Recent experimental research and clinical studies have clarified important pathways in the production of reactive oxygen and nitrogen species. Free radicals are involved in causing cerebral damage after perinatal hypoxia-ischemia affecting membrane lipids, proteins, and DNA. Anti-oxidant strategies can be used as add-on neuroprotective therapy after perinatal oxidative stress. Selective inhibitors of neuronal and inducible nitric oxide synthase, allopurinol, melatonin, and erythropoietin are among the first compounds that are ready for clinical trials.

Association between oxidative stress in pregnancy and preterm premature rupture of membranes

BACKGROUND

Premature rupture of membranes (PROM) is caused by collagen damage in the chorioamniotic sac leading to tearing. Reactive oxygen species (ROS) may be the cause of collagen damage. Isoprostanes (F(2)-IP) are produced by ROS attack on polyunsaturated fatty acids and are sensitive and specific biomarkers of lipid-peroxidation in vivo.

AIM

To verify whether oxidative stress occurs in pregnancies associated with preterm PROM.

METHODS

F(2)-IPs were measured in amniotic fluid of 16 pregnancies with preterm PROM (Group II) and 97 without PROM (Group I).

RESULTS

F(2)-IP concentrations (pg/mL) were significantly higher in group II than group I (p<0.0001). The ROC curve showed a sensitivity of 100% and a specificity of 84.5% at a cut-off of 124.4 pg/mL.

CONCLUSIONS

An association exists between oxidative stress in pregnancy and preterm PROM. The detection of amniotic fluid F(2)-IP concentrations seems to be a reliable predictive index of risk of preterm PROM.

Urinary F2-isoprostanes are poor prognostic indicators for the development of bronchopulmonary dysplasia

OBJECTIVE

Oxygen toxicity is thought to contribute to the development of bronchopulmonary dysplasia (BPD). Oxidant injury leads to formation of F(2)-isoprostanes (F(2)-IsoP). We hypothesized that urinary excretion of the stable metabolite of F(2)-IsoP, 8-iso-PGF(2alpha), would be higher in infants who develop BPD than those who did not.

METHODS

Forty infants <30-weeks gestational age (GA) were enrolled, 24 infants with BPD and 16 without BPD. Urine specimens were collected weekly and stored at -80 degrees C until analyzed. Urinary 8-iso-PGF(2alpha) was measured by gas chromatography/mass spectrometry (GC-MS) and normalized to creatinine excretion.

RESULTS

GA and birth weight (BW) were lower in infants who developed BPD than those who did not. Urinary 8-iso-PGF(2alpha) levels in the first or third weeks of age were not significantly different between the two groups.

CONCLUSION

Urinary excretion of 8-iso-PGF(2alpha) in early postnatal life in preterm infants is not correlated with the development of BPD.

Melatonin levels during the first week of life and their relation with the antioxidant response in the perinatal period

AIM

Melatonin is a potent free radical scavenger and an indirect antioxidant. Knowledge about the behavior of melatonin secretion in the early neonatal period, which may relate to its properties at a vital stage during very high antioxidant demands, is limited.

PATIENTS AND METHODS

We studied 35 newborns admitted to the Neonatal Unit with respiratory distress syndrome (RDS) and with no signs of sepsis, severe anemia, hemodynamic compromise or malformation. The gestational age of the newborns was 26-40 weeks (mean value 32.5 weeks) and the weight at birth was 870-4,400 g (mean value 1,800 g). They were classified into two groups: <or=1,500 g or >1,500 g birthweight. In all cases, at 09:00 h on their 1st, 3rd and 7th days of life, serum melatonin was measured by RIA. The clinical history was recorded and treatment and follow-up were performed according to established neonatology practice, and the resultant data recorded. Informed consent from the parents or guardians was obtained in accordance with the Declaration of Helsinki. Statistical analysis was carried out using ANOVA-II (factor I: day of sample; factor II: birthweight).

RESULTS

There were significant increases in melatonin levels with increasing birthweight (p = 0.017), but no changes by day of sample. Although in both study groups melatonin levels increased during the first few days this was not statistically significant.

CONCLUSIONS

In newborns of low birthweight, we report high melatonin concentrations in the morning and during the first week of life. These increase with maturation, and at full-term were similar to nocturnal levels during the acrophase of pineal gland secretion in toddlers and schoolage children, when pineal gland secretion is maximal and takes place reflecting environmental variations. In the early neonatal period these high levels of melatonin seem to derive from extrapineal sources, which mature to provide antioxidant protection in accordance with other elements of the antioxidant network to compensate for the high levels of oxidative stress that are present in the perinatal period.

Oxidative stress and antioxidant status in fetal circulation in preeclampsia

Preeclampsia is associated with oxidative stress in maternal circulation. The purpose of this study was to explore oxidative stress and antioxidants in the fetal circulation in preeclampsia. Women with preeclampsia (n = 19) or uncomplicated pregnancies (n = 33) delivered by cesarean section were included. Blood was sampled separately from the umbilical vein and artery. 8-Iso-prostaglandin F(2alpha) (8-isoprostane), a stable product of lipid peroxidation, is a reliable marker of oxidative stress. Concentration of total 8-isoprostane in cord plasma was analyzed by gas chromatography-mass spectrometry. Antioxidant status was evaluated measuring ferric reducing ability of plasma and vitamin E. There was no difference between preeclampsia and control groups regarding median plasma concentration of 8-isoprostane in umbilical vein (955 versus 780 pg/mL, p = 0.41) or in umbilical artery (233 versus 276 pg/mL, p = 0.65). Concentration of 8-isoprostane was much higher in plasma from the umbilical vein than artery, suggesting placenta as the source of 8-isoprostane. Median ferric reducing ability of plasma concentration was higher in preeclampsia than in controls, both in the umbilical vein and artery. Median vitamin E concentration in the umbilical vein was higher in preeclampsia, but no difference was found in the umbilical artery. In conclusion, no evidence of increased oxidative stress, evaluated by 8-isoprostane concentration, was found in fetal circulation in preeclampsia.

Lipid peroxidation in cord blood and neonatal outcome

BACKGROUND

Periventricular-intraventricular hemorrhage, necrotizing enterocolitis, chronic lung disease and retinopathy of prematurity have been referred to as oxygen radical diseases (ORD) because they are thought to be related to excess oxidant stress relative to anti-oxidant defenses in premature infants. 8-Isoprostane is a product of lipid peroxidation that can be used as a measure of free radical exposure or injury. The aim of the present study was to determine whether fetal oxidant stress is associated with adverse effects in preterm infants.

METHODS

Mothers delivering at gestational age <37 weeks were recruited. Umbilical arterial and venous cord blood samples were collected and 8-isoprostane levels measured. Levels of 8-isoprostane in cord blood were correlated with maternal and perinatal variables, neonatal mortality, and the development of one or more ORD.

RESULTS

Umbilical cord venous, but not arterial, 8-isoprostane levels were associated with mortality and the development of one or more of the ORD. After controlling for gestational age, for each unit change in the log value of 8-isoprostane in venous cord blood the odds of mortality were 12 (95% confidence interval [CI]: 1-223) and oxygen radical disease were 2.7 (95%CI: 1-7.2). Isoprostane levels were not related to gender, method of delivery, use of maternal magnesium or steroids, pregnancy-induced hypertension, or delivery room resuscitation.

CONCLUSION

Oxidant stress in utero may be an important determinant of mortality and morbidity in preterm infants. Elevated umbilical venous isoprostane levels suggest that oxidative injury to maternal and placental tissues predispose to adverse neonatal outcomes.

Oxidative stress and autologous immunoglobulin G binding to band 3 dimers in newborn erythrocytes

Since birth-induced oxidative stress (OS) results in the removal of erythrocytes from the blood stream, we studied the binding of autologous IgG to erythrocyte band 3 dimers (the 170-kDa band, which marks the erythrocytes for removal) in preterm and term newborns and in adults. The 170-kDa band was present in as much as 74% of preterm, in 21% of term newborns, and in 10% of adults. During erythrocyte ageing "in vitro" (0, 24, and 48 h aerobic incubation), the appearance of the band occurred much faster with erythrocytes from newborns (particularly preterm) than with those from adults. When the blots for the 170-kDa band were quantified by scanning densitometry, it was seen that the 0 time values were significantly higher in preterm compared to term and adult values. After aerobic incubation a progressive increase in the optical density was observed in each group and the densities were higher in preterm than in the other groups. The course of iron release during the various incubations was analogous to that of the 170-kDa band blots, and significant correlations were found at 0 and 48 h. Methemoglobin formation roughly paralleled iron release. Esterified F(2)-isoprostanes (markers of OS) and O(2)(-) production in the nonincubated (0 time) erythrocytes were much higher in newborn (preterm and term) than in adult erythrocytes. Plasma free F(2)-isoprostanes were significantly higher in preterms than in terms and in terms than in adults. Plasma non-protein-bound iron (NPBI) was higher in preterm than in term newborns and not detectable in adults. In conclusion dimers of band 3 with autologous IgG are found under conditions in which OS can be detected in erythrocytes or in plasma: namely in newborns or in aged erythrocytes.

F2-isoprostanes stimulate collagen synthesis in activated hepatic stellate cells: a link with liver fibrosis?

Carbon tetrachloride (CCl4)-induced hepatic fibrosis has been considered to be linked to oxidative stress and mediated by aldehydic lipid peroxidation products. In the present study, we investigated whether collagen synthesis is induced by F2-isoprostanes, the most proximal products of lipid peroxidation and known mediators of important biological effects. By contrast with aldehydes, F2-isoprostanes act through receptors able to elicit definite signal transduction pathways. In a rat model of CCl4-induced hepatic fibrosis, plasma F2-isoprostanes were markedly elevated for the entire experimental period; hepatic collagen content also increased. When hepatic stellate cells (HSCs) from normal liver were cultured with F2-isoprostanes in the concentration range found in the in vivo studies (10(-9)-10(-8) M), a striking increase in DNA synthesis (reversed by the thromboxane A2 antagonist SQ 29 548), in cell proliferation and in collagen synthesis was observed. Total collagen content was similarly increased. Moreover, F2-isoprostanes markedly increased the production of transforming growth factor-beta1 by U937 cells, considered a model of liver macrophages. The data provide evidence for the possibility that F2-isoprostanes generated by lipid peroxidation in hepatocytes mediate HSC proliferation and collagen production seen in hepatic fibrosis.

Role of oxidative stress in female reproduction

In a healthy body, ROS (reactive oxygen species) and antioxidants remain in balance. When the balance is disrupted towards an overabundance of ROS, oxidative stress (OS) occurs. OS influences the entire reproductive lifespan of a woman and even thereafter (i.e. menopause). OS results from an imbalance between prooxidants (free radical species) and the body's scavenging ability (antioxidants). ROS are a double-edged sword - they serve as key signal molecules in physiological processes but also have a role in pathological processes involving the female reproductive tract. ROS affect multiple physiological processes from oocyte maturation to fertilization, embryo development and pregnancy. It has been suggested that OS modulates the age-related decline in fertility. It plays a role during pregnancy and normal parturition and in initiation of preterm labor. Most ovarian cancers appear in the surface epithelium, and repetitive ovulation has been thought to be a causative factor. Ovulation-induced oxidative base damage and damage to DNA of the ovarian epithelium can be prevented by antioxidants. There is growing literature on the effects of OS in female reproduction with involvement in the pathophysiology of preeclampsia, hydatidiform mole, free radical-induced birth defects and other situations such as abortions. Numerous studies have shown that OS plays a role in the pathophysiology of infertility and assisted fertility. There is some evidence of its role in endometriosis, tubal and peritoneal factor infertility and unexplained infertility. This article reviews the role OS plays in normal cycling ovaries, follicular development and cyclical endometrial changes. It also discusses OS-related female infertility and how it influences the outcomes of assisted reproductive techniques. The review comprehensively explores the literature for evidence of the role of oxidative stress in conditions such as abortions, preeclampsia, hydatidiform mole, fetal embryopathies, preterm labour and preeclampsia and gestational diabetes. The review also addresses the growing literature on the role of nitric oxide species in female reproduction. The involvement of nitric oxide species in regulation of endometrial and ovarian function, etiopathogenesis of endometriosis, and maintenance of uterine quiescence, initiation of labour and ripening of cervix at parturition is discussed. Complex interplay between cytokines and oxidative stress in the etiology of female reproductive disorders is discussed. Oxidant status of the cell modulates angiogenesis, which is critical for follicular growth, corpus luteum formation endometrial differentiation and embryonic growth is also highlighted in the review. Strategies to overcome oxidative stress and enhance fertility, both natural and assisted are delineated. Early interventions being investigated for prevention of preeclampsia are enumerated. Trials investigating combination intervention strategy of vitamin E and vitamin C supplementation in preventing preeclampsia are highlighted. Antioxidants are powerful and there are few trials investigating antioxidant supplementation in female reproduction. However, before clinicians recommend antioxidants, randomized controlled trials with sufficient power are necessary to prove the efficacy of antioxidant supplementation in disorders of female reproduction. Serial measurement of oxidative stress biomarkers in longitudinal studies may help delineate the etiology of some of the diosorders in female reproduction such as preeclampsia.

A normotriglyceridemic, low HDL-cholesterol phenotype is characterised by elevated oxidative stress and HDL particles with attenuated antioxidative activity

OBJECTIVE

Low levels of high density lipoprotein-cholesterol (HDL-C) are highly prevalent in subjects presenting premature atherosclerosis. It is indeterminate as to whether high cardiovascular risk in low HDL-C subjects occurs concomitantly with elevated oxidative stress and/or with biologically dysfunctional HDL particles.

METHODS AND RESULTS

Systemic oxidative stress (as plasma 8-isoprostanes) was 2.3-fold elevated (p<0.05) in normocholesterolemic, normotriglyceridemic, normoglycemic low HDL-C subjects (plasma HDL-C, <40 mg/dL; n=8) as compared to normolipidemic controls (n=15). HDL subfractions (HDL2b, 2a, 3a, 3b and 3c) isolated by density gradient ultracentrifugation from low HDL-C subjects displayed significantly lower (-21 to -43%, p<0.05) specific antioxidative activity (sAA; capacity to protect LDL from oxidation on a unit particle mass or on a particle number basis) as compared to controls. Altered chemical composition (core triglyceride enrichment, cholesteryl ester depletion) paralleled antioxidative dysfunction of HDL subfractions. Plasma 8-isoprostane levels negatively correlated with sAA of HDL subfractions and positively correlated with the total cholesterol/HDL-C ratio, which was significantly elevated in the low HDL-C phenotype.

CONCLUSIONS

Low HDL-C subjects display elevated oxidative stress and possess HDL particle subspecies with attenuated intrinsic antioxidative activity which is intimately related to their altered chemical composition.