H.M. Berger

The total free radical trapping ability of cord blood plasma in preterm and term babies.

ABSTRACT: The interaction between various antioxidants may be important in protecting the newborn baby against oxygen toxicity. We studied the total radical trapping capacity of the antioxidants in plasma (TRAP) and compared the TRAP level in the preterm and term baby (cord blood) with that in adults. In addition, the concentrations of various known antioxidants were measured and the theoretical contribution of these antioxidants to the TRAP calculated. The measured and calculated TRAP were higher in the newborn babies than the adults. The uric acid concentration was similar in the three groups but the vitamin C concentration was higher and the vitamin E and sulfhydryl concentrations were lower in the newborn babies. In contrast to the adult group, the measured TRAP in the newborn babies did not correlate with the calculated TRAP. This may be due to differences in inhibition or recycling of antioxidants in the newborn and adult groups. Theoretical considerations showed that there may be a large unidentified group of antioxidants that contribute to measured TRAP in plasma. Bilirubin and β-carotene were measured (higher and lower concentrations, respectively, in the newborn) in an attempt to identify these antioxidants. The efficient plasma radical trapping capacity in the cord blood may partly compensate for deficiencies in other components of the antioxidant defenses, e.g. cellular enzymes, at the time of birth.

Impaired plasma antioxidative defense and increased nontransferrin-bound iron during high-dose chemotherapy and radiochemotherapy preceding bone marrow transplantation

To analyze the effects of radiochemotherapy on the pro-oxidative/antioxidative balance in plasma, we measured the total radical antioxidant parameter of plasma (TRAP) and single plasma antioxidants (uric acid, sulfhydryl groups, alpha-tocopherol, ubiquinone-10/total coenzyme-Q10 ratio, ascorbate, and bilirubin) every 12 h during high-dose chemotherapy and radiochemotherapy preceding bone marrow transplantation (BMT). Nontransferrin-bound iron (NTBI) was monitored as a potential pro-oxidant. Plasma levels of polyunsaturated fatty acids (PUFA) were measured as substrates, and thiobarbituric acid-reactive substances (TBARS) were measured as products of lipid peroxidation. Allantoin was analyzed as the product of uric acid oxidation. Patients receiving busulfan, VP-16, and cyclophosphamide (BU/VP/CY) (n = 8) were compared with those receiving total body irradiation in addition to VP-16 and cyclophosphamide (TBI/VP/CY) (n = 8). TRAP values were within the normal range before therapy and decreased after BU/VP/CY by 37% (p <. 02) and after TBI/VP/CY by 39% (p <.02). During TBI and after VP-16, a temporary increase in TRAP values occurred, which was not related to changes in individual antioxidants. In vitro experiments confirmed that VP-16 had an antioxidative effect. The concentration of uric acid declined in both groups and correlated with TRAP (BU/VP/CY: r =.80, p <.001; TBI/VP/CY: r =.84, p <.001). Levels of NTBI, which is normally not found in plasma, increased rapidly during conditioning therapy (p <.02 in both groups) and correlated inversely with TRAP (weighted intraindividual Spearman rank correlation coefficient for both groups: NTBI and TRAP: r = -.59, p <.001) and PUFA (in the radiochemotherapy group: r = -.67, p <.001). Whereas PUFA declined (p <.02 in both groups), TBARS increased (p <. 05 in both groups). Furthermore, an increase of allantoin and ubiquinone-10/total coenzyme-Q10 ratio in the BU/VP/CY group was found (allantoin: p <.02; ubiquinone-10/total coenzyme-Q10 ratio: p <.05). Antioxidants only partially recovered to baseline values until day 14 after BMT. Our findings indicate oxidative stress after high-dose radiochemotherapy and suggest a contribution of NTBI therein.

Human milk vitamin content after pasteurisation, storage, or tube feeding.

We investigated the effect of the composition of the storage container, Holder pasteurisation, and conditions during tube feeding on the concentration of selected vitamins in human milk. Though the fat soluble vitamins A, D, and E were not affected, the concentration of several water soluble vitamins decreased. The lower vitamin C concentration of milk stored in polypropylene containers compared with milk stored in glass containers (29%) was not significant. Holder pasteurisation significantly lowered the concentrations of vitamins C (36%), folacin (31%), and B6 (15%). Tube feeding significantly lowered the concentrations of vitamins C (44%) and B6 (19%), and exposure to phototherapy seemed to lower the vitamin C concentration (53%) further. Low birthweight infants have increased vitamin requirements. Vitamin losses in expressed human milk before or during feeding may increase the incidence of vitamin deficiencies in these babies.

Effect of interleukin 8 in meconium on in-vitro neutrophil chemotaxis

BACKGROUND Pneumonitis, characterised by large numbers of neutrophils in the lung, is an important feature of the meconium aspiration syndrome. The mechanism underlying the neutrophil influx is not known. We have investigated whether meconium has chemotactic activity and whether such activity is related to the presence of interleukin 8. METHODS The chemotactic activity of meconium on neutrophils from newborn infants was assessed in a Boyden-chamber assay. Interleukin 8 and formyl-methionyl-leucyl-phenylalanine (f-MLP) served as positive controls. Inhibition of chemotaxis was assessed with monoclonal antibody to interleukin 8. The interleukin-8 concentration was measured by ELISA. FINDINGS Sterile meconium suspension from seven unrelated newborn babies increased migration of neutrophils from neonates in comparison with random migration (79, 72, 70, 50, 58, 88 microm vs 46 microm; p<0.001). This effect was greatest at a meconium concentration of 5 g/L, although differences between samples from individual babies were observed. Interleukin 8 was present in all meconium suspensions (480-3980 ng/L). Anti-interleukin-8 inhibited neutrophil migration. INTERPRETATION Interleukin 8 is present in meconium and it induces chemotaxis of neutrophils in vitro. This mechanism may have a role in the pathogenesis of pneumonitis in meconium aspiration syndrome.

Ferrous Ions Detected in Iron-Overloaded Cord Blood Plasma From Preterm and Term Babies: Implications for Oxidative Stress

Redox active iron chelatable to bleomycin is often present in the plasma of cord blood samples taken from preterm and term babies. The low caeruloplasmin and high ascorbate levels in plasma at birth may allow this iron to exist in the reduced ferrous state. In support of this postulate thirteen cord blood samples showing the presence of low molecular mass iron were able to degrade DNA in the presence of bleomycin and plasma.

Effect of deferoxamine and allopurinol on non-protein-bound iron concentrations in plasma and cortical brain tissue of newborn lambs following hypoxia-ischemia.

Reduction of non-protein-bound iron (NPBI) using iron chelators may attenuate hypoxia-ischemia-induced reperfusion injury of the brain. This study investigated whether administration of low-dose deferoxamine and allopurinol, both having NPBI-chelating properties, reduced hypoxia-ischemia-induced NPBI formation in plasma effluent from the brain and in cerebral cortical tissue. Twenty-one newborn lambs underwent severe hypoxia-ischemia. Upon reperfusion and reoxygenation the lambs received either a placebo (n = 7), or deferoxamine 2.5 mg/kg (n = 7) or allopurinol 20 mg/kg (n = 7). The post-hypoxic-ischemic NPBI levels in plasma were significantly lower after deferoxamine but not after allopurinol as compared to placebo-treated lambs. Cortical NPBI levels in both deferoxamine and allopurinol-treated lambs were significantly lower than NPBI levels in placebo-treated lambs. We conclude that deferoxamine effectively lowers NPBI in plasma effluent from the brain, and that both, deferoxamine and allopurinol, lower NPBI in cortical brain tissue.

Uric acid and ascorbic acid redox ratios in plasma and tracheal aspirate of preterm babies with acute and chronic lung disease.

This study compared plasma redox ratios of uric acid and ascorbic acid in well preterm babies with those with respiratory distress syndrome (RDS) and chronic lung disease (CLD), and investigated the relationship between these ratios and their respective measurements in tracheal aspirate. On day 1 after birth, plasma allantoin and allantoin/uric acid ratio were elevated in CLD (p < .05), and both markers of oxidative stress enabled early prediction of development of CLD (sensitivity and specificity: 54 and 83%, respectively). The relation between allantoin production and oxidative stress is supported by the correlation between the allantoin level and oxygen therapy in both RDS and CLD (p < .05). Reduced and oxidize ascorbic acid in plasma decreased postnatally in all groups and their redox ratio remained stable. Uric acid and ascorbic acid redox ratios were significantly elevated in tracheal aspirates compared to plasma samples (p < .05), and there was a strong positive correlation between both ratios (p < .005). These markers may be useful in monitoring babies with respiratory distress.

Lipid peroxidation in human milk and infant formula: effect of storage, tube feeding and exposure to phototherapy

Preformed lipid peroxidation products present in the feed may contribute to the total reactive oxygen radical load infants have to deal with and may play a role in the pathogenesis of necrotizing enterocolitis and bronchopulmonary dysplasia. In this study, the occurrence of lipid peroxidation in human milk and feeding formulas for preterm babies was evaluated in vitro. Free linoleic acid (18:2) and its hydroperoxide (18:2OOH) were measured by gas chromatography‐mass spectrometry and the concentration of 18:2OOH and the 18:2OOH/18:2 ratio were used as indices of peroxidation. In all feeds peroxidation products were present, but the proportion of peroxidized 18:2 was greater in infant formula. Storage of human milk (+4°C for four days) increased lipid peroxidation. Exposure to light during tube feeding incrcased pcroxidation in infant formula but not in human milk. Different procedures for preparation, storage and feeding may decrease the concentration of these potentially toxic peroxidized lipids in human milk and infant formula.

The Effect of Antioxidative Combination Therapy on Post Hypoxic-Ischemic Perfusion, Metabolism, and Electrical Activity of the Newborn Brain

Reoxygenation and reperfusion after severe hypoxia and ischemia (HI) contribute substantially to birth asphyxia-related brain injury. Excess production of free radicals via metabolization of arachidonic acid, xanthine oxidase, and non-protein-bound iron play an important role. Cerebral reperfusion injury is characterized by a decrease in perfusion, oxygen consumption, and electrical activity of the brain. Reduction of free radical production may attenuate these features. We therefore induced severe HI in 35 newborn lambs, and upon reperfusion the lambs received a placebo [control(CONT), n = 7], the cyclooxygenase inhibitor indomethacin (INDO, 0.3 mg/kg/i.v., n = 7), the xanthine oxidase inhibitor allopurinol(ALLO, 20 mg/kg/i.v., n = 7), the iron chelator deferoxamine (DFO, 2.5 mg/kg/i.v., n = 7), or a combination of these drugs (COMB,n = 7). In each group changes (%) from pre-HI values were investigated for brain perfusion [measured by carotid artery flow(Qcar, mL/min)], (relative) cerebral O2 metabolism(CMRO2), and electrocortical brain activity (ECBA, µV) at 15, 60, 120, and 180 min post-HI. Qcar decreased significantly at 120 and 180 min post-HI in CONT (p < 0.05), but not in INDO, ALLO, DFO, and COMB groups. CMRO2 decreased significantly in CONT at 60 min post-HI (p < 0.05), remained stable in DFO and INDO, and was significantly higher in ALLO and COMB (p < 0.05) at 120 and 180 min post-HI. ECBA was significantly lower in CONT during the whole post-HI period (p < 0.05), ECBA in INDO and COMB were significantly decreased at 60 and 120 min post-HI (p < 0.05), but recovered afterward, whereas DFO and ALLO remained stable during the post-HI period. In conclusion preservation of Qcar and CMRO2, and recovery of ECBA occurred after treatment with INDO, ALLO, and DFO; combination of these drugs did not have an additional positive effect.

Influence of long chain unsaturated fatty acids in formula feeds on lipid peroxidation and antioxidants in preterm infants.

The influence of long chain polyunsaturated fatty acids (LCP) in formula feeds on lipid peroxidation and antioxidants was studied in 35 healthy preterm infants (gestational age 30-35 wk) during the first 6 postnatal weeks. Infants received a preterm formula supplemented with n-3 LCP (LCP group,n = 13), or standard preterm formula (NO-LCP group, n = 15); 7 infants fed human milk served as a reference group. With LCP supplementation, erythrocyte C22:6n-3 levels were stable; without supplementation, the levels declined (difference p < 0.001). LCP supplementation did not decrease vitamin E or C levels, or increase lipid peroxidation products (thiobarbituric acid-reactive substances) in plasma. In erythrocytes, LCP supplementation did not markedly influence the reduced/oxidized glutathione ratio; however, the susceptibility to H2O2-induced oxidative stress was reduced. Our results suggest that healthy preterm infants are able to cope with any extra peroxidative stress produced by n-3 LCP supplementation. However, these findings might not be generally applicable to other formulas containing LCP supplements.