Temporal patterns of circulating cell-free DNA (cfDNA) in a newborn piglet model of perinatal asphyxia.

Perinatal asphyxia is a severe medical condition resulting from oxygen deficiency (hypoxia) at the time of birth, causing worldwide approximately 680,000 newborn deaths every year. Better prediction of severity of damages including early biomarkers is highly demanded. Elevated levels of circulating cell-free DNA (cfDNA) in blood have been reported for a range of different diseases and conditions, including cancer and prematurity. The objective of this study was to validate methods for assessing cfDNA in blood and cerebrospinal fluid (CSF) and to explore temporal variations in a piglet model of neonatal hypoxia-reoxygenation. Different cfDNA extraction methods in combination with cfDNA detection systems were tested, including a fluorescent assay using SYBR Gold and a qRT-PCR-based technique. Newborn piglets (n = 55) were exposed to hypoxia-reoxygenation, hypoxia-reoxygenation and hypothermia, or were part of the sham-operated control group. Blood was sampled at baseline and at post-intervention, further at 30, 270, and 570 minutes after the end of hypoxia. Applying the fluorescent method, cfDNA concentration in piglets exposed to hypoxia (n = 32) increased from 36.8±27.6 ng/ml prior to hypoxia to a peak level of 61.5±54.9 ng/ml after the intervention and deceased to 32.3±19.1 ng/ml at 570 minutes of reoxygenation, whereas the group of sham-operated control animals (n = 11) revealed a balanced cfDNA profile. Animals exposed to hypoxia and additionally treated with hypothermia (n = 12) expressed a cfDNA concentration of 54.4±16.9 ng/ml at baseline, 39.2±26.9 ng/ml at the end of hypoxia, and of 41.1±34.2 ng/ml at 570 minutes post-intervention. Concentrations of cfDNA in the CSF of piglets exposed to hypoxia revealed at post-intervention higher levels in comparison to the controls. However, these observations were only tendencies and not significant. In a first methodological proof-of-principle study exploring cfDNA using a piglet model of hypoxia-reoxygenation variations in the temporal patterns suggest that cfDNA might be an early indicator for damages caused by perinatal asphyxia.

N-Acetylcysteine Amide Exerts Possible Neuroprotective Effects in Newborn Pigs after Perinatal Asphyxia.

BACKGROUND: Perinatal asphyxia and ensuing reoxygenation change the antioxidant capacity of cells and organs. OBJECTIVES: To analyze the neuroprotective effect of the antioxidant N-acetylcysteine amide (NACA) after perinatal hypoxia-reoxygenation with an emphasis on proinflammatory cytokines and the transcription factor NF-κB in the prefrontal cortex of neonatal pigs. METHODS: Twenty-nine newborn pigs, aged 12-36 h, were subjected to global hypoxia and hypercapnia. One sham-operated group (n = 5) and 2 experimental groups (n = 12) were exposed to 8% oxygen, until the base excess was -20 mmol/l or the mean arterial blood pressure fell to <20 mm Hg (asphyxia with NACA or saline). The pigs were observed for 9.5 h after hypoxia. Samples of prefrontal cortex and plasma were analyzed. RESULTS: Cortex: there was no significant difference in mRNA expression between the intervention groups regarding IL-1ß, IL6, TNFα, MMP2, MMP9 or IL18. Pigs exposed to hypoxia-reoxygenation and treatment with NACA (NACA-pigs) had a significantly lower protein concentration of IL-1ß than pigs treated with saline (placebo controls), i.e. 8.8 ± 3.9 versus 16.8 ± 10.5 pg/mg protein (p = 0.02). The activation of the transcription factor NF-κB (measured as the fold-change of phosphorylated p65Ser 536), was reduced in the NACA-pigs when compared to the placebo controls (5.2 ± 4.3 vs. 16.0 ± 13.5; p = 0.02). No difference between the intervention groups regarding brain histopathology or in the levels of 8-oxoguanine measured in the prefrontal cortex were observed. Plasma: the NACA-pigs had a stronger reduction of TNFα in the first 30 min following asphyxia compared with the placebo controls, i.e. 36 (30-44) versus 24 (14-32)% (p = 0.01). CONCLUSION: The reduced levels of the pivotal inflammatory markers IL-1ß and TNFα and the transcription factor NF-κB may indicate that NACA has possible neuroprotective effects after perinatal asphyxia.

Perinatal Asphyxia May Influence the Level of Beta-Amyloid (1-42) in Cerebrospinal Fluid: An Experimental Study on Newborn Pigs.

OBJECTIVE: Total tau (T-tau), phosphorylated tau (p-Tau) and Beta-Amyloid 1-42 (AB42) in Cerebrospinal Fluid (CSF) are useful biomarkers in neurodegenerative diseases. The aim of the study was to investigate the role of these and other CSF biomarkers (T-tau, p-Tau, AB42, S100B and NSE), during hypoxia-reoxygenation in a newborn pig model. DESIGN: Thirty newborn pigs were included in a study of moderate or severe hypoxia. The moderate hypoxia group (n = 12) was exposed to global hypoxia (8% O2) until Base excess (BE) reached -15 mmol/l. The pigs in the group exposed to severe hypoxia (n = 12) received 8% O2 until BE reached -20 mmol/l or mean Blood Pressure fell below 20 mm Hg, The control group (n = 6) was kept at room air. For all treatments, the CSF was collected at 9.5 hours after the intervention. RESULTS: The level of AB42 in CSF was significantly lower in the pigs exposed to severe hypoxia compared with the control group, 922(SD +/-445)pg/ml versus. 1290(SD +/-143) pg/ml (p<0.05), respectively. Further, a non-significant reduction of AB42 was observed in the group exposed to moderate hypoxia T-tau and p-Tau revealed no significant differences between the intervention groups and the control group, however a significantly higher level of S100B was seen in the CSF of pigs receiving hypoxia in comparison to the level in the control group. Further on, there was a moderate negative correlation between the levels of AB42 and S100B in CSF, as well as a moderate negative correlation between Lactate in blood at end of hypoxia and AB42 in CSF. INTERPRETATION: This is the first study to our knowledge that demonstrated a significant drop in AB42 in CSF after neonatal hypoxia. Whether or not this has an etiological basis for adult neurodegenerative disorders needs to be studied with additional experiments and epidemiological studies. AB42 and S100B are significantly changed in neonatal pigs subjected to hypoxia compared to controls and thus may be valuable biomarkers of perinatal asphyxia.

Cesarean section is associated with more frequent pneumothorax and respiratory problems in the neonate.

We have investigated whether the incidence of neonatal pneumothorax (NP), use of mechanical ventilation (MV) or Continuous Positive Airways Pressure (CPAP) is increased in neonates delivered at term and preterm by cesarean section (CS). All deliveries at Ullevål University Hospital, Oslo, during the period 2001-2005 (n=29,358) were included, among whom 5,957 were delivered by CS (20.3%). Data were collected on mode of delivery, elective or emergency CS, gestational age, maternal age, gender and parity. Among the 26,664 neonates born at term (> or =37th gestational week), 4,546 were delivered by CS (17.0%), of whom 0.5% by elective and 0.6% by emergency CS with NP. The incidence of diagnosed NP was significantly higher after CS than after vaginal delivery (0.6% vs. 0.10%, p<0.001). In addition, the need for MV was significantly increased (0.41% vs. 0.19%; p=0.01) but use of CPAP was not (0.28%vs. 0.15%; p=0.08). Among 2,694 neonates born preterm (<37th gestational week), 1,266 were delivered by CS (47.0%). The incidence of diagnosed NP was 2.05% when delivered by CS but only 0.63% when delivered vaginally (p<0.01). Among the preterm infants delivered by CS, 17.7% needed CPAP compared to 6.9% when delivered vaginally (p<0.001) and MV was required for 8.1 and 3.7% (p<0.001), respectively. Among neonates delivered at term or moderately preterm (30-36 weeks) by CS the incidence of NP and other respiratory problems was significantly increased.