Surfactant-secreted phospholipase A2 interplay and respiratory outcome in preterm neonates.

Secreted phospholipase A2 hydrolyzes surfactant phospholipids and is crucial for the inflammatory cascade; preterm neonates are treated with exogenous surfactant, but the interaction between surfactant and phospholipase is unknown. We hypothesize that this interplay is complex and the enzyme plays a relevant role in neonates needing surfactant replacement. We aimed to: 1) identify phospholipases A2 isoforms expressed in preterm lung; 2) study the enzyme role on surfactant retreatment and function and the effect of exogenous surfactant on the enzyme system; and 3) verify whether phospholipase A2 is linked to respiratory outcomes. In bronchoalveolar lavages of preterm neonates, we measured enzyme activity (alone or with inhibitors), enzyme subtypes, surfactant protein-A, and inflammatory mediators. Surfactant function and phospholipid profile were also tested. Urea ratio was used to obtain epithelial lining fluid concentrations. Follow-up data were prospectively collected. Subtype-IIA is the main phospholipase isoform in preterm lung, although subtype-IB may be significantly expressed. Neonates needing surfactant retreatment have higher enzyme activity (P = 0.021) and inflammatory mediators (P always ≤ 0.001) and lower amounts of phospholipids (P always < 0.05). Enzyme activity was inversely correlated to surfactant adsorption (ρ = -0.6; P = 0.008; adjusted P = 0.009), total phospholipids (ρ = -0.475; P = 0.05), and phosphatidylcholine (ρ = -0.622; P = 0.017). Exogenous surfactant significantly reduced global phospholipase activity (P < 0.001) and subtype-IIA (P = 0.005) and increased dioleoylphosphatidylglycerol (P < 0.001) and surfactant adsorption (P < 0.001). Enzyme activity correlated with duration of ventilation (ρ = 0.679, P = 0.005; adjusted P = 0.04) and respiratory morbidity score at 12 mo postnatal age (τ-b = 0.349, P = 0.037; adjusted P = 0.043) but was not associated with mortality, bronchopulmonary dysplasia, or other long-term respiratory outcomes.

Patent ductus arteriosus in preterm infants born before 30 weeks' gestation: high rate of spontaneous closure after hospital discharge.

AimThe aim of this study was to determine the spontaneous closure rate of patent ductus arteriosus at a 2-year follow-up, following failed medical therapy and beyond initial hospital discharge, and to evaluate in-hospital spontaneous or pharmacological closure rates.Materials and methodsA retrospective evaluation was conducted in a cohort of preterm infants admitted to the Neonatal ICU of Ancona between January, 2004 and June, 2013. Inclusion criteria were gestational age between 24+0 and 29+6 weeks or birth weight 1.5 mm, a left atrium-to-aorta ratio >1.4, and/or reversal of end-diastolic flow in the aorta >30% of the anterograde. First-line treatment was intravenous ibuprofen. Intravenous indomethacin was used if ibuprofen failed. Surgical ligation was considered in haemodynamically significant patent ductus arteriosus after medical treatment. RESULTS: A total of 593 infants met the inclusion criteria, and patent ductus arteriosus was diagnosed in 317 (53.4%). Among them, 283 (89.3%) infants had haemodynamically significant patent ductus arteriosus, with pharmacological closure achieved in 228 (80.6%) infants and surgical ligation performed in 20 (7.1%). Follow-up at 24 months was available for 39 (81.3%) of 48 infants with patent ductus arteriosus at the hospital discharge: 36 (92.3%) underwent spontaneous closure, two (5.1%) underwent surgical ligation, and one (2.6%) had a patent ductus arteriosus.DiscussionA significant number of patent ductus arteriosus that fail pharmacological closure undergo spontaneous closure by the age of 2 years. This information should be taken into account when considering surgery or additional attempts of pharmacological closure.

Modes of Death in a Pediatric Cardiac ICU.

OBJECTIVE: To determine epidemiology and proximate causes of death in a pediatric cardiac ICU in Southern Europe. DESIGN: Retrospective chart review. SETTING: Single-center institution. PATIENTS: We concurrently identified 57 consecutive patients who died prior to discharge from the cardiac ICU. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Over the study period, there were 57 deaths for a combined mortality rate of 2.4%. Four patients (7%) were declared brain dead, 25 patients (43.8%) died after a failed resuscitation attempt, and 28 patients (49.1%) died after withholding or withdrawal of life-sustaining treatment. Cardiorespiratory failure was the most frequent proximate cause of death (39, 68.4%) followed by brain injury (14, 24.6%) and septic shock (4, 7%). Older age at admission, presence of mechanical ventilation and/or device-dependent nutrition support, patients on a left-ventricular assist device and longer cardiac ICU stay were more likely to have life support withheld or withdrawn. CONCLUSIONS: Almost half of the deaths in the cardiac ICU are predictable, and they are anticipated by the decision to limit life-sustaining treatments. Brain injuries play a direct role in the death of 25% of patients who die in the cardiac ICU. Patients with left-ventricular assist device are associated with withdrawal of treatment.

Airway metabolic anomalies in adolescents with bronchopulmonary dysplasia: new insights from the metabolomic approach.

OBJECTIVES: To assess a group of adolescents with bronchopulmonary dysplasia (BPD) from a biochemical-metabolic standpoint, applying the metabolomic approach to studying their exhaled breath condensate (EBC). STUDY DESIGN: Twenty adolescents with BPD (mean age 14.8 years) and 15 healthy controls (mean age 15.2 years) were recruited for EBC collection, exhaled nitric oxide measurement, and spirometry. The EBC samples were analyzed using a metabolomic approach based on mass spectrometry. The obtained spectra were analyzed using multivariate statistical analysis tools. RESULTS: A reliable Orthogonal Projections to Latent Structures-Discriminant Analysis model showed a clear discrimination between cases of BPD and healthy controls (R(2) = 0.95 and Q(2) = 0.92). The search for putative biomarkers identified an altered complex lipid profile in the adolescents with BPD. CONCLUSIONS: The metabolomic analysis of EBC distinguishes cases of BPD from healthy individuals, suggesting that the lung of survivors of BPD is characterized by long-term metabolic abnormalities. The search for putative biomarkers indicated a possible role of an altered surfactant composition, which may persist far beyond infancy.

Surface film formation in vitro by infant and therapeutic surfactants: role of surfactant protein B.

BACKGROUND: Pulmonary surfactant provides an alveolar surface-active film that is critical for normal lung function. Our objective was to determine in vitro film formation properties of therapeutic and infant surfactants and the influence of surfactant protein (SP)-B content. METHODS: We used a multiwell fluorescent assay measuring maximum phospholipid surface accumulation (Max), phospholipid concentration required for half-maximal film formation (½Max), and time for maximal accumulation (tMax). RESULTS: Among five therapeutic surfactants, calfactant (highest SP-B content) had film formation values similar to natural surfactant, and addition of SP-B to beractant (lowest SP-B) normalized its Max value. Addition of budesonide to calfactant did not adversely affect film formation. In tracheal aspirates of preterm infants with evolving chronic lung disease, SP-B content correlated with ½Max and tMax values, and SP-B supplementation of SP-B-deficient infant surfactant restored normal film formation. Reconstitution of normal surfactant indicated a role for both SP-B and SP-C in film formation. CONCLUSION: Film formation in vitro differs among therapeutic surfactants and is highly dependent on SP-B content in infant surfactant. The results support a critical role of SP-B for promoting surface film formation.

Surfactant protein B and A concentrations are increased in neonatal pneumonia.

BACKGROUND: Term newborns with pneumonia show a reduced pulmonary compliance due to multiple and ill-defined factors. Surfactant proteins' (SPs) changes could have a role in the reduced compliance but the matter is still unsettled. The aim of this study was to clarify the meaning of SPs changes during pneumonia in term newborns. METHODS: In 28 term ventilated newborns, 13 with pneumonia and 15 with no lung disease, we measured SP-B, SP-A, disaturated-phosphatidylcholine (DSPC), and total phospholipids (PL) concentrations in tracheal aspirates at intubation and close to extubation. We also measured DSPC kinetics using (U-(13)C-PA)dipalmitoyl-phosphatidylcholine. RESULTS: At baseline, SP-B, expressed as % of PL, was significantly different between the groups, being 3.5-fold higher in pneumonia than controls. Conversely, SP-A did not vary between the groups. At extubation, SP-B and SP-A concentrations had decreased significantly in newborns with pneumonia, while there was no significant change in controls. DSPC t1/2 was significantly shorter in the pneumonia group (11.8 (5.5-19.8) h vs. 26.6 (19.3-63.6) h, P = 0.011). CONCLUSION: In term newborns with pneumonia, SP-B increases with respect to PL, and DSPC is turned over at a faster rate. Disease's resolution is associated with the restoration of the normal ratio between SP-B and PL.

Surfactant protein C metabolism in human infants and adult patients by stable isotope tracer and mass spectrometry.

Surfactant protein C (SP-C) is deemed as the surfactant protein most specifically expressed in type II alveolar epithelial cells and plays an important role in surfactant function. SP-C turnover in humans and its meaning in the clinical context have never been approached. In this study, we used mass spectrometry to investigate SP-C turnover in humans. We studied four infants and eight adults requiring mechanical ventilation. All patients had no lung disease. Patients received a 24-h continuous infusion of (13)C-leucine as precursor of SP-C, and serial tracheal aspirates and plasma samples were obtained every 6 h till 48 h. SP-C was isolated from tracheal aspirates by sorbent-phase chromatography. (13)C-leucine SP-C enrichment could be successfully measured in three infant and in four adult samples by using mass spectrometry coupled with a gas chromatographer. Median SP-C fractional synthesis rate, secretion time, and peak time were 15.7 (14.1-27.5)%/day, 6.0 (4.7-11.5) h, and 24 (20-27) h. In conclusion, this study shows that it is feasible to accurately determine SP-C turnover in humans by stable isotopes.

Impaired surfactant protein B synthesis in infants with congenital diaphragmatic hernia.

Pulmonary hypoplasia and hypertension account for significant morbidity and mortality in neonates with congenital diaphragmatic hernia (CDH). Whether CDH is associated with surfactant dysfunction remains controversial. Therefore, we measured disaturated phosphatidylcholine (DSPC) and surfactant protein (SP)-B concentration in tracheal aspirates and their synthesis rate in infants with CDH compared to infants without lung disease. (2)H2O as a precursor of DSPC and 1-(13)C-leucine as a precursor of SP-B were administered to 13 infants with CDH and eight controls matched for gestational age. DSPC and SP-B were isolated from tracheal aspirates, and their fractional synthesis rate was derived from (2)H and (13)C enrichment curves obtained by mass spectrometry. DSPC and SP-B amounts in tracheal aspirates were also measured. In infants with CDH, SP-B fractional synthesis rate and amount were 62±27% and 57±22% lower, respectively, than the value found in infants without lung disease (p<0.01 and p<0.05, respectively). There were no significant group differences in DSPC fractional synthesis rate and amount. Infants with CDH have a lower rate of synthesis of SP-B and less SP-B in tracheal aspirates. In these infants, partial SP-B deficiency could contribute to the severity of respiratory failure and its correction might represent a therapeutic goal.

Targeting 2.5 versus 4 g/kg/day of amino acids for extremely low birth weight infants: a randomized clinical trial.

OBJECTIVE: To compare the effect of 2.5 vs 4 g/kg/d of amino acid (AA) in parenteral nutrition of extremely low birth weight infants on metabolic tolerance, short-term growth, and neurodevelopment. STUDY DESIGN: One hundred thirty-one infants with birth weight between 500 and 1249 g were randomized to 2.5 (standard AA [SAA] group) or 4 (high AA [HAA] group) g/kg/d AA intake, with equal nonprotein energy. The primary outcome was body size at 36 weeks. RESULTS: One hundred thirty-one patients were randomized and 114 analyzed (58 SAA group and 56 HAA group). Study groups had similar demographics and clinical characteristics. Elevated blood urea (BU >70 mg/dL = BU nitrogen >32.6 mg/dL) occurred in 24% vs 59% (P = .000) and hyperglycemia (>175 mg/dL) in 34% vs 11% (P = .003) of the SAA and HAA patients, respectively. Body weight, length, and head circumference at 36 weeks and 2 years were similar between groups. Bayley Scales of Infant and Toddler Development, Third Edition score was 94 ± 13 in the SAA group and 97 ± 15 in the HAA group (P = .35). CONCLUSIONS: The HAA group had higher BU levels and better glucose control. An extra 8 g/kg of AA over the first 10 days of life did not improve growth and neurodevelopment.

Assessment of modified ultrafiltration hemodynamic impact by pressure recording analytical method during pediatric cardiac surgery.

OBJECTIVE: Modified ultrafiltration is commonly used in pediatric cardiac surgery. Although its clinical benefits are currently debated, modified ultrafiltration has proved to improve mean arterial pressure in the first postoperative hours. Aim of our study was to measure cardiac index, stroke volume index, and mean arterial pressure modification before and after modified ultrafiltration by means of Pressure Recording Analytical Method. DESIGN: Single-center prospective observational cohort study. SETTING: Pediatric cardiac surgery operating room. PATIENTS: Children below 20 kg that are included in the "pediatric" mode of Pressure Recording Analytical Method. MEASUREMENTS AND MAIN RESULTS: Forty patients were enrolled in this study. Median age, weight, and body surface area at surgery were 3 months (interquartile range, 10 days to 3.5 yr), 5.6 (3.1-15) kg, and 0.31 (0.21-0.56), respectively. During the modified ultrafiltration procedure, a median volume of 17 mL/kg (11-25) was ultrafiltered and a median volume of 11 mL/kg (6-17) was reinfused with a median final modified ultrafiltration balance of -0.15 mL/kg (-4.0 to 0.1). By univariate analyses, there was a 10% increase in postmodified ultrafiltration mean, systolic and diastolic pressures (p = 0.01), stroke volume index (p = 0.02), and cardiac index (p = 0.001) without significant changes in heart rate, central (left and right) venous pressures, stroke volume variation, and inotropic score. By multivariate analysis, when controlling for cardiopulmonary bypass time and age at surgery, cardiac index variation was independently associated with lower preoperative body surface area (beta coefficient -5.5, p = 0.04). CONCLUSIONS: According to Pressure Recording Analytical Method assessment, modified ultrafiltration acutely improves myocardial function, as shown by a 10% increase of systemic arterial pressure, stroke volume index, and cardiac index. This effect is more pronounced in smaller sized patients.

A method to determine the kinetics of multiple proteins in human infants with respiratory distress syndrome.

We report a method to measure in vivo turnover of four proteins from sequential tracheal aspirates obtained from human newborn infants with respiratory distress syndrome using targeted proteomics. We detected enrichment for all targeted proteins approximately 3 h from the start of infusion of [5,5,5-(2)H(3)] leucine, secretion times that varied from 1.2 to 2.5 h, and half lives that ranged between 10 and 21 h. Complement factor B, a component of the alternative pathway of complement activation, had an approximately twofold-longer half-life than the other three proteins. In addition, the kinetics of mature and carboxy-terminal tryptic peptides from the same protein (surfactant protein B) were not statistically different (p = 0.49).

Balloon atrial septostomy and pre-operative brain injury in neonates with transposition of the great arteries: a systematic review and a meta-analysis.

OBJECTIVE: To perform a systematic review and a meta-analysis of the effects of balloon atrial septostomy on peri-operative brain injury in neonates with transposition of the great arteries. DATA SOURCE: We conduct a systematic review of the literature to identify all observational studies that included neonates born with transposition of the great arteries who had peri-operative evidence of brain injury. STUDY SELECTION AND DATA EXTRACTION: The search strategy produced three prospective and two retrospective cohort studies investigating the association between balloon atrial septostomy and brain injury totalling 10,108 patients. In two studies, the outcome was represented by the presence of a coded diagnosis of a clinically evident stroke at discharge, whereas in three studies the outcome was represented by the finding of pre-operative brain injury identified by magnetic resonance scans. DATA SYNTHESIS: The overall brain injury rate for neonates who underwent balloon atrial septostomy versus control patients was 60 of 2273 (2.6%) versus 45 of 7835 (0.5%; pooled odds ratio, 1.90; 95% confidence intervals, 0.93-3.89; p = 0.08). A subgroup analysis of the three studies that used pre-operative brain injury as the primary outcome found no significant association between balloon atrial septostomy and brain injury (pooled odds ratio, 2.70; 95% confidence intervals, 0.64-11.33; p = 0.17). Balloon atrial septostomy frequency was 22.4% (2273 of 10,108), with reported rates ranging from 20% to 75%. CONCLUSION: Our analysis shows that balloon atrial septostomy is not associated with increased odds for peri-operative brain injury. Balloon atrial septostomy should still be used for those patients with significant hypoxaemia, haemodynamic instability, or both.

Altered surfactant homeostasis and recurrent respiratory failure secondary to TTF-1 nuclear targeting defect.

BACKGROUND: Mutations of genes affecting surfactant homeostasis, such as SFTPB, SFTPC and ABCA3, lead to diffuse lung disease in neonates and children. Haploinsufficiency of NKX2.1, the gene encoding the thyroid transcription factor-1 (TTF-1)--critical for lung, thyroid and central nervous system morphogenesis and function--causes a rare form of progressive respiratory failure designated brain-lung-thyroid syndrome. Molecular mechanisms involved in this syndrome are heterogeneous and poorly explored. We report a novel TTF-1 molecular defect causing recurrent respiratory failure episodes in an infant. METHODS: The subject was an infant with severe neonatal respiratory distress syndrome followed by recurrent respiratory failure episodes, hypopituitarism and neurological abnormalities. Lung histology and ultrastructure were assessed by surgical biopsy. Surfactant-related genes were studied by direct genomic DNA sequencing and array chromatine genomic hybridization (aCGH). Surfactant protein expression in lung tissue was analyzed by confocal immunofluorescence microscopy. For kinetics studies, surfactant protein B and disaturated phosphatidylcholine (DSPC) were isolated from serial tracheal aspirates after intravenous administration of stable isotope-labeled (2)H(2)O and (13)C-leucine; fractional synthetic rate was derived from gas chromatography/mass spectrometry (2)H and (13)C enrichment curves. Six intubated infants with no primary lung disease were used as controls. RESULTS: Lung biopsy showed desquamative interstitial pneumonitis and lamellar body abnormalities suggestive of genetic surfactant deficiency. Genetic studies identified a heterozygous ABCA3 mutation, L941P, previously unreported. No SFTPB, SFTPC or NKX2.1 mutations or deletions were found. However, immunofluorescence studies showed TTF-1 prevalently expressed in type II cell cytoplasm instead of nucleus, indicating defective nuclear targeting. This pattern has not been reported in human and was not found in two healthy controls and in five ABCA3 mutation carriers. Kinetic studies demonstrated a marked reduction of SP-B synthesis (43.2 vs. 76.5 ± 24.8%/day); conversely, DSPC synthesis was higher (12.4 vs. 6.3 ± 0.5%/day) compared to controls, although there was a marked reduction of DSPC content in tracheal aspirates (29.8 vs. 56.1 ± 12.4% of total phospholipid content). CONCLUSION: Defective TTF-1 signaling may result in profound surfactant homeostasis disruption and neonatal/pediatric diffuse lung disease. Heterozygous ABCA3 missense mutations may act as disease modifiers in other genetic surfactant defects.

Disaturated-phosphatidylcholine and surfactant protein-B turnover in human acute lung injury and in control patients.

BACKGROUND: Patients with adult respiratory distress syndrome (ARDS) and acute lung injury (ALI) have low concentrations of disaturated-phosphatidylcholine and surfactant protein-B in bronchoalveolar lavage fluid. No information is available on their turnover. OBJECTIVES: To analyze disaturated-phosphatidylcholine and surfactant protein-B turnover in patients with ARDS/ALI and in human adults with normal lungs (controls). METHODS: 2H2O as precursor of disaturated-phosphatidylcholine-palmitate and 113C-Leucine as precursor of surfactant protein-B were administered intravenously to 12 patients with ARDS/ALI and to 8 controls. Disaturated-phosphatidylcholine and surfactant protein-B were isolated from serial tracheal aspirates, and their fractional synthetic rate was derived from the 2H and 13C enrichment curves, obtained by gas chromatography mass spectrometry. Disaturated-phosphatidylcholine, surfactant protein-B, and protein concentrations in tracheal aspirates were also measured. RESULTS: 1) Surfactant protein-B turned over at faster rate than disaturated-phosphatidylcholine both in ARDS/ALI patients and in controls. 2) In patients with ARDS/ALI the fractional synthesis rate of disaturated-phosphatidylcholine was 3.1 times higher than in controls (p < 0.01), while the fractional synthesis rate of surfactant protein-B was not different. 3) In ARDS/ALI patients the concentrations of disaturated-phosphatidylcholine and surfactant protein-B in tracheal aspirates were markedly and significantly reduced (17% and 40% of the control values respectively). CONCLUSIONS: 1) Disaturated-phosphatidylcholine and surfactant protein-B have a different turnover both in healthy and diseased lungs. 2) In ARDS/ALI the synthesis of these two surfactant components may be differently regulated.

Secondary hyperparathyroidism is associated with postpartum blood pressure in preeclamptic women and normal pregnancies.

BACKGROUND: Preeclampsia has been associated with features of secondary hyperparathyroidism. In this study, we examine the relationships of calcium metabolism with blood pressure (BP) in preeclamptic women and in a control group of normal (NORM) pregnancies in the postpartum. METHODS: Sixty-three consecutive preeclamptic women (age 35 ±â€Š6 years) were studied 4 weeks after delivery. We collected clinical and lab information on pregnancy and neonates and measured plasma and urinary calcium and phosphate, plasma parathyroid hormone (PTH) and 25-hydroxy vitamin D [25(OH)D], and performed 24-h ambulatory BP monitoring. BP and calcium metabolism of 51 preeclamptic were compared with 17 NORM pregnant women that matched for age, race, and postpartum BMI. RESULTS: 25(OH)D deficiency (<10 ng/ml) was found in 3% of preeclamptic women, insufficiency (10-30 ng/ml) in 67%, and NORM values (31-100 ng/ml) in the remaining 30%. Elevated plasma PTH (≥79 pg/ml) was found in 24% of preeclamptic women who had 25(OH)D plasma levels of 21.4 ±â€Š8.3 ng/ml. In these women, PTH levels was independently associated with 24-h SBP and DBP and daytime and night-time DBP. Prevalence of nondippers and reverse dippers was elevated (75% and 33%, respectively). No associations between calcium metabolism and neonates' characteristics of preeclamptic women were observed. Prevalence of vitamin D deficiency and insufficiency and of elevated plasma PTH levels were comparable in matched groups. Considering preeclamptic women and matched controls as a whole group, office SBP and DBP levels were associated with PTH independently of preeclampsia and other confounders. CONCLUSION: Features of secondary hyperparathyroidism are common in the postpartum. Preeclampsia and increased PTH levels were both independent factors associated with increased BP after delivery, and both might affect the future cardiovascular risk of these women.

Metabolic precursors of surfactant disaturated-phosphatidylcholine in preterms with respiratory distress.

Our objective was to study the metabolic precursors of surfactant disaturated-phosphatidylcholine (DSPC) in preterm infants with respiratory distress syndrome (RDS) on mechanical ventilation. We performed 46 DSPC kinetic studies in 23 preterms on fat-free parenteral nutrition and mechanical ventilation (birth weight = 1167 +/- 451 g, gestational age = 28.5 +/- 2.0 weeks). Eight infants received a simultaneous intravenous infusion of U(13)C-glucose and [16,16,16](2)H-palmitate, eight infants received U(13)C-glucose and (2)H(2)O, and seven received U(13)C-palmitate and (2)H(2)O. Surfactant DSPC kinetics were calculated from the isotopic enrichments of DSPC-palmitate from sequential tracheal aspirates and its metabolic precursors in plasma or urine. DSPC fractional synthesis rate (FSR) was 17 +/- 11, 21 +/- 16, and 15 +/- 6%/day from glucose, palmitate, and body water, respectively (P = 0.36). DSPC-FSR from U(13)C-glucose and (2)H(2)O were significantly correlated and yielded similar estimates (difference of -0.1 +/- 3%) (P = 0.91). The difference in the 15 infants receiving palmitate versus (2)H(2)O or palmitate versus glucose was +6.0 +/- 12%/day (P = 0.21). There was a significant correlation between DSPC-FSRs from plasma glucose and plasma FFA. The contribution of glucose versus palmitate to DSPC-FSR was 49 +/- 20% versus 51 +/- 20%, respectively. Plasma glucose and FFA showed similar contributions to DSPC-FSR in infants with RDS and fat-free parenteral nutrition. FSRs from (2)H(2)O or glucose were highly correlated.

Synthesis of long-chain polyunsaturated fatty acids in preterm newborns fed formula with long-chain polyunsaturated fatty acids.

BACKGROUND: Docosahexaenoic acid (DHA) and arachidonic acid (AA) are long-chain polyunsaturated fatty acids (LCPs) that play pivotal roles in growth and neurodevelopment. OBJECTIVE: We aimed to quantify the synthesis of LCPs in preterm infants fed infant formula containing LCPs. DESIGN: Twenty-two preterm infants were randomly assigned to either the no-LCP group (fed formula without LCPs; n = 11) or the LCP group (fed formula with LCPs; n = 11). Dietary LCPs had higher (13)C content than did the endogenously synthesized LCPs, which were derived from linoleic and alpha-linolenic acids. The (13)C content of major selected plasma fatty acids was measured by using gas chromatography-isotope ratio mass spectrometry at birth and at age 1, 3, and 7 mo. Absolute LCP synthesis and the percentage of LCP synthesis relative to dietary intake were calculated. RESULTS: Percentage AA synthesis was 67.2 +/- 7.8%, 35.9 +/- 9.8%, and 29.0 +/- 10.3%, and that of DHA was 41.7 +/- 14.9%, 10.5 +/- 8.1%, and 7.4 +/- 6.2% at 1, 3, and 7 mo old, respectively. Absolute AA synthesis was 26.7 +/- 4.2, 14.4 +/- 3.9, and 11.6 +/- 4.1 mg x kg(-1) x d(-1) and that of DHA was 12.6 +/- 4.5, 3.2 +/- 2.5, and 2.3 +/- 1.9 mg x kg(-1) . d(-1) at 1, 3, and 7 mo old, respectively. AA and DHA synthesis decreased significantly (P < 0.01) with time, and AA synthesis was significantly (P < 0.01) greater than DHA synthesis. CONCLUSIONS: By this novel approach, we measured endogenous LCP synthesis in infants receiving dietary LCPs over long periods. By age 7 mo, LCP synthesis was dramatically lower in preterm infants fed LCPs.

Surfactant disaturated-phosphatidylcholine kinetics in acute respiratory distress syndrome by stable isotopes and a two compartment model.

BACKGROUND: In patients with acute respiratory distress syndrome (ARDS), it is well known that only part of the lungs is aerated and surfactant function is impaired, but the extent of lung damage and changes in surfactant turnover remain unclear. The objective of the study was to evaluate surfactant disaturated-phosphatidylcholine turnover in patients with ARDS using stable isotopes. METHODS: We studied 12 patients with ARDS and 7 subjects with normal lungs. After the tracheal instillation of a trace dose of 13C-dipalmitoyl-phosphatidylcholine, we measured the 13C enrichment over time of palmitate residues of disaturated-phosphatidylcholine isolated from tracheal aspirates. Data were interpreted using a model with two compartments, alveoli and lung tissue, and kinetic parameters were derived assuming that, in controls, alveolar macrophages may degrade between 5 and 50% of disaturated-phosphatidylcholine, the rest being lost from tissue. In ARDS we assumed that 5-100% of disaturated-phosphatidylcholine is degraded in the alveolar space, due to release of hydrolytic enzymes. Some of the kinetic parameters were uniquely determined, while others were identified as lower and upper bounds. RESULTS: In ARDS, the alveolar pool of disaturated-phosphatidylcholine was significantly lower than in controls (0.16 +/- 0.04 vs. 1.31 +/- 0.40 mg/kg, p < 0.05). Fluxes between tissue and alveoli and de novo synthesis of disaturated-phosphatidylcholine were also significantly lower, while mean resident time in lung tissue was significantly higher in ARDS than in controls. Recycling was 16.2 +/- 3.5 in ARDS and 31.9 +/- 7.3 in controls (p = 0.08). CONCLUSION: In ARDS the alveolar pool of surfactant is reduced and disaturated-phosphatidylcholine turnover is altered.

Short-Term Stability of Whole Blood Polyunsaturated Fatty Acid Content on Filter Paper During Storage at -28 °C.

Finger or heel-pricked blood sampling for fatty acid analysis is suitable especially in newborn infants where blood sampling is difficult and phlebotomy for research can be unethical. The aim of this study was to evaluate dried blood long chain polyunsaturated fatty acids (LC-PUFA) stability during storage at -28 °C. We collected 12 blood cord samples that were analyzed immediately after blood drawing, with and without drying the blood on filter paper. Dried samples were then analyzed 7 days and 1, 3, and 6 months after collection. Butylated hydroxytoluene was added to all samples. Fatty acid composition and (13)C enrichment were measured by gas chromatography and by gas chromatography-isotope ratio mass spectrometry, respectively. The fatty acid composition, expressed in mol%, of the major LC-PUFA at day 7 was not statistically different from time 0, however lower values were found by the first month of storage. The (13)C enrichment of 20:4n-6 and 22:6n-3 did not differ during the whole study period. LC-PUFA analysis from dried umbilical cord blood in neonates should be performed within a week, major losses of LC-PUFA occur afterwards. However, fatty acids obtained from dried blood maintain their (13)C enrichment value for up to 6 months and thus these samples are suitable for natural abundance isotopic studies.

Cardiopulmonary Bypass Increases Plasma Glial Fibrillary Acidic Protein Only in First Stage Palliation of Hypoplastic Left Heart Syndrome.

BACKGROUND: Univentricular congenital heart defects require open-heart surgery soon after birth, and are associated with risk of brain injury and poor neurologic outcome. METHODS: This is a prospective, observational study on children undergoing cardiac surgery. Plasma glial fibrillary acidic protein (GFAP), as an early marker of brain injury, was measured by ELISA at the end of anaesthesia induction, initiation of cardiopulmonary bypass (CPB), the end of cooling, the end of rewarming, the end of CPB, and after protamine administration. We recorded clinical and surgical parameters to assess which CPB phase and clinical parameters were associated with a GFAP increase. RESULTS: We studied 13 children less than 50 months of age: 8 underwent Norwood or Damus-Kaye-Stansel palliation (group 1) and 5 underwent Fontan procedure (group 2). A GFAP increase was only observed in group 1, with the highest median value at the end of rewarming. No quantifiable levels of GFAP were measured at pre-bypass and the start of CPB stages in all patients. End of cooling and CPB-end GFAP, GFAP maximum value, and GFAP area under the curve all correlated with the CPB time spent at a cerebral regional saturation < 45% (P = 0.021, 0.028, 0.007, 0.021, respectively). CONCLUSIONS: Children with univentricular heart defects exhibit a CPB plasma-GFAP increase only after stage 1 palliation. The maximum GFAP increase occurred at the end of rewarming. Further studies are needed to identify which clinical or surgical parameter(s) could reflect a GFAP increase during surgery for congenital heart defects, and whether GFAP levels correlate with the neurologic outcome.