Functional morphometry: non-invasive estimation of the alveolar surface area in extremely preterm infants.

BACKGROUND: The main pathophysiologic characteristic of chronic respiratory disease following extremely premature birth is arrested alveolar growth, which translates to a smaller alveolar surface area (SA). We aimed to use non-invasive measurements to estimate the SA in extremely preterm infants. METHODS: Paired measurements of the fraction of inspired oxygen and transcutaneous oxygen saturation were used to calculate the ventilation/perfusion ratio, which was translated to SA using Fick's law of diffusion. The SA was then adjusted using volumetric capnography. RESULTS: Thirty infants with a median (range) gestational age of 26.3 (22.9-27.9) weeks were studied. The median (range) adjusted SA was 647.9 (316.4-902.7) cm2. The adjusted SA was lower in the infants who required home oxygen [637.7 (323.5-837.5) cm2] compared to those who did not [799.1 (444.2-902.7) cm2, p = 0.016]. In predicting the need for supplemental home oxygen, the adjusted SA had an area under the receiver operator characteristic curve of 0.815 (p = 0.017). An adjusted SA ≥688.6 cm2 had 86% sensitivity and 77% specificity in predicting the need for supplemental home oxygen. CONCLUSIONS: The alveolar surface area can be estimated non-invasively in extremely preterm infants. The adjusted alveolar surface area has the potential to predict the subsequent need for discharge home on supplemental oxygen. IMPACT: We describe a novel biomarker of respiratory disease following extremely preterm birth. The adjusted alveolar surface area index was derived by non-invasive measurements of the ventilation/perfusion ratio and adjusted by concurrent measurements of volumetric capnography. The adjusted alveolar surface area was markedly reduced in extremely preterm infants studied at 7 days of life and could predict the need for discharge home on supplemental oxygen. This method could be used at the bedside to estimate the alveolar surface area and provide an index of the severity of lung disease, and assist in monitoring, clinical management and prognosis.

Effects of human milk on body composition and growth in very low birthweight infants.

OBJECTIVE: To compare body composition and growth in very low birthweight infants according to their source of human milk: maternal expressed breast milk (MEBM) versus donor breast milk (DBM). We hypothesized that infants fed predominately MEBM would exhibit reduced body fat percentage compared to those fed predominately DBM. METHODS: Premature infants weighing ≤1500 g on an exclusive human milk diet were enrolled in a single-center study between 2017 and 2021. Demographic data and anthropometric measurements were collected. All infants underwent body composition analysis via dual energy x-ray absorptiometry at 36 weeks corrected post menstrual age. RESULTS: A total of 60 infants were enrolled and 48 were included in the primary analysis. No differences were detected in percent body fat (14 vs. 12%, p = 0.7) or fat-free mass (2050 vs. 2130 g, p = 0.7). Both groups displayed similar growth and anthropometric measurements. Caloric and macronutrient intake between groups was similar. CONCLUSION: In the cohort of patients studied, no differences were observed in percent body fat based on primary human milk type intake in the first 28 postnatal days. Further investigation is required in a larger population of exclusive human milk fed preterm infants to determine if body composition differences exist based on an infant's primary human milk source. IMPACT: Premature infants are at risk for altered body composition at term corrected age, specifically increased body fat percentage, which may have implications for the future. To our knowledge this is the first study exploring body composition outcomes based on an infant's primary human milk source. Infants fed exclusive human milk (e.g., donor vs. maternal) displayed similar percent body fat and growth outcomes.

Understanding increased ferritin levels in pediatric ECMO patients.

Abnormally high serum ferritin levels have been reported during pediatric ECMO, attributed to frequent red blood cell transfusion and suggestive of iron overload. However, the utility of ferritin for diagnosing iron overload is complicated by its response as an acute-phase reactant. In this study, we aimed to assess the utility of ferritin for diagnosing ECMO-related iron overload, with secondary aims of understanding its relationship with inflammation and erythropoiesis. Ferritin was elevated in all pediatric ECMO runs (median 459 ng/ml, IQR = 327.3-694.4). While intermittent elevations in serum iron were observed, all normalized prior to decannulation. Unreported previously, erythropoietin (EPO) remained well above normative values prior to and throughout ECMO runs, despite frequent transfusion and exposure to hyperoxia. Ferritin correlated poorly with serum iron [r(80) = 0.05, p = 0.65], but correlated well with IL-6 [r(76) = 0.48, p < 0.001] and EPO [r(81) = 0.55, p < 0.001]. We suggest that serum ferritin is a poor biomarker of iron overload in ECMO patients, and that future investigation into its relationship with EPO is warranted.

Effects of antenatal betamethasone on preterm human and mouse ductus arteriosus: comparison with baboon data.

BACKGROUND: Although studies involving preterm infants ≤34 weeks gestation report a decreased incidence of patent ductus arteriosus after antenatal betamethasone, studies involving younger gestation infants report conflicting results. METHODS: We used preterm baboons, mice, and humans (≤276/7 weeks gestation) to examine betamethasone's effects on ductus gene expression and constriction both in vitro and in vivo. RESULTS: In mice, betamethasone increased the sensitivity of the premature ductus to the contractile effects of oxygen without altering the effects of other contractile or vasodilatory stimuli. Betamethasone's effects on oxygen sensitivity could be eliminated by inhibiting endogenous prostaglandin/nitric oxide signaling. In mice and baboons, betamethasone increased the expression of several developmentally regulated genes that mediate oxygen-induced constriction (K+ channels) and inhibit vasodilator signaling (phosphodiesterases). In human infants, betamethasone increased the rate of ductus constriction at all gestational ages. However, in infants born ≤256/7 weeks gestation, betamethasone's contractile effects were only apparent when prostaglandin signaling was inhibited, whereas at 26-27 weeks gestation, betamethasone's contractile effects were apparent even in the absence of prostaglandin inhibitors. CONCLUSIONS: We speculate that betamethasone's contractile effects may be mediated through genes that are developmentally regulated. This could explain why betamethasone's effects vary according to the infant's developmental age at birth.

Favorable Outcomes of Preterm Infants With Parenteral Nutrition-associated Liver Disease Treated With Intravenous Fish Oil-based Lipid Emulsion.

OBJECTIVES: The aim of the study was to determine the acute and long-term outcomes of preterm infants treated with an intravenous fish oil-based lipid emulsion (FishLE) for parenteral nutrition-associated liver disease (PNALD). METHODS: Preterm infants 14 days to 24 months of age with anatomic short gut or severe intestinal dysmotility, serum direct bilirubin ≥4 mg/dL, and requiring >60% calories from parenteral nutrition were eligible. Enrolled infants received 1 g ·â€Škg ·â€Šday of FishLE until resolution of direct hyperbilirubinemia or return of enteral nutrition. Acute clinical effects and biochemical markers of liver function were monitored. Growth and developmental scores at 6 and 12 months postmenstrual age (PMA) were assessed and compared with controls matched by gestational age (GA). RESULTS: Thirteen patients with mean GA of 28 ±â€Š4 weeks were treated and compared with 119 GA-matched controls. Their mean direct bilirubin was 9.8 ±â€Š6.4 mg/dL at enrollment. All infants had resolution of cholestasis after study completion. There were no acute adverse events, deaths, or liver/intestinal transplants. Weight and head circumference were similar between FishLE-treated patients and controls at 6- and 12-month PMA. Cognitive and motor scores were decreased at 6 and 12 months PMA in FishLE-treated infants. Logistic regression analysis showed that prolonged hospitalization was detrimental to cognitive and motor development, whereas treatment was not. CONCLUSIONS: The use of intravenous FishLEs in premature infants appears to be safe and reverses PNALD despite significant liver disease and intestinal failure. This therapy should be used in preterm infants with PNALD and followed long term to evaluate development.

Hyperglycemia increases the risk of death in extremely preterm baboons.

BACKGROUND: Transient neonatal hyperglycemia (HG) has been reported in up to 80% of extremely preterm human infants. We hypothesize that severe HG is associated with increased morbidity and mortality in preterm baboons. METHODS: Sixty-six baboons born at 67% of gestation were studied. HG was defined as serum glucose level ≥150 mg/dl during the first week of life. Animals were stratified into two groups: severe HG (≥8 events) and nonsevere HG (<8 events). RESULTS: HG developed in 65 of the 66 (98%) baboons that were included. A total of 3,386 glucose measurements were obtained. The mean serum glucose level was 159 ± 69 mg/dl for the severe HG group and 130 ± 48 mg/dl for the nonsevere HG group during the first week of life. No differences were found in gender, birth weight, sepsis, patent ductus arteriosus, or oxygenation/ventilation indexes between groups. Severe HG was associated with early death even after controlling for sepsis, postnatal steroid exposure, and catecholamine utilization. CONCLUSION: HG is common in preterm baboons and is not associated with short-term morbidity. Severe HG occurring in the first week of life is associated with early death in preterm baboons.

Prophylactic Administration of Mesenchymal Stromal Cells Does Not Prevent Arrested Lung Development in Extremely Premature-Born Non-Human Primates.

Premature birth is a leading cause of childhood morbidity and mortality and often followed by an arrest of postnatal lung development called bronchopulmonary dysplasia. Therapies using exogenous mesenchymal stromal cells (MSC) have proven highly efficacious in term-born rodent models of this disease, but effects of MSC in actual premature-born lungs are largely unknown. Here, we investigated thirteen non-human primates (baboons; Papio spp.) that were born at the limit of viability and given a single, intravenous dose of ten million human umbilical cord tissue-derived MSC per kilogram or placebo immediately after birth. Following two weeks of human-equivalent neonatal intensive care including mechanical ventilation, lung function testing and echocardiographic studies, lung tissues were analyzed using unbiased stereology. We noted that therapy with MSC was feasible, safe and without signs of engraftment when administered as controlled infusion over 15 minutes, but linked to adverse events when given faster. Administration of cells was associated with improved cardiovascular stability, but neither benefited lung structure, nor lung function after two weeks of extrauterine life. We concluded that a single, intravenous administration of MSC had no short- to mid-term lung-protective effects in extremely premature-born baboons, sharply contrasting data from term-born rodent models of arrested postnatal lung development and urging for investigations on the mechanisms of cell-based therapies for diseases of prematurity in actual premature organisms.

Effects of ibuprofen treatment on the developing preterm baboon kidney.

Preterm neonates are commonly exposed postnatally to pharmacological treatments for a patent ductus arteriosus. Exposure of the developing kidney to nephrotoxic medications may adversely impact renal development. This study aimed to determine the effect of early postnatal ibuprofen treatment, both alone and in combination with a nitric oxide synthase inhibitor (NOSi), on renal development and morphology. Baboon neonates were delivered prematurely at 125-day (125d) gestation (term = 185d) and were euthanized at birth or postnatal day 6. Neonates were divided into four groups: 125d gestational controls (n = 8), Untreated (n = 8), Ibuprofen (n = 6), and ibuprofen (Ibu)+NOSi (n = 4). Animals in the Ibuprofen and Ibu+NOSi groups received five doses of ibuprofen, with the Ibuprofen+NOSi animals additionally administered a NOS inhibitor (N(G)-monomethyl-l-arginine). There was no difference among groups in body weight, kidney weight, or glomerular generation number. Nephrogenic zone width was significantly reduced in the Ibuprofen group (123.5 ± 7.4 µm) compared with the 125d gestational control (176.1 ± 6.9 µm) and Untreated animals (169.7 ± 78.8 µm). In the Ibu+NOSi group, nephrogenic zone width averaged 152.7 ± 3.9 µm, which was not significantly different from any other group. Morphologically abnormal glomeruli were present at a range of 0.0-22.9% in the Untreated group, 0.0-6.1% in the Ibuprofen group, and 0.0-1.4% in the Ibu+NOSi group. In conclusion, early postnatal ibuprofen exposure is associated with a reduced nephrogenic zone width, which may suggest the early cessation of nephrogenesis following treatment. Ultimately, this may impact the number of nephrons formed in the preterm kidney.

MR imaging correlates of white-matter pathology in a preterm baboon model.

INTRODUCTION: Cerebral white-matter (WM) abnormalities on magnetic resonance imaging (MRI) correlate with neurodevelopmental disability in infants born prematurely. RESULTS: Quantitative histological measures of WM and ventricular volumes correlated with qualitative MRI scores of WM volume loss and ventriculomegaly. Diffuse astrocytosis was associated with signal abnormality on T(2)-weighted imaging and higher apparent diffusion coefficient in WM. Loss of oligodendrocytes was associated with lower relative anisotropy characterized by higher radial diffusivity values. The relationship between histopathology and MRI abnormalities was more pronounced in animals in the 28 d model, equivalent to the term human infant. DISCUSSION: MRI reflects microstructural and anatomical abnormalities that are characteristic of WM injury in the preterm brain, and these changes are more evident on MRI at term-equivalent postmenstrual age. METHODS: We assessed the histopathological correlates of MRI abnormalities in a baboon model of premature birth. Baboons were delivered at 125 d of gestation (dg, term ~185 dg) and maintained in an animal intensive care unit for 14 (n = 26) or 28 d (n = 17). Gestational control animals were delivered at 140 dg (n = 9) or 153 dg (n = 4). Cerebral WM in fixed brains was evaluated using MRI, diffusion tensor imaging (DTI), and histopathology.

Functional morphometry to estimate the alveolar surface area using a premature baboon model.

The main respiratory pathophysiological process following premature birth is the delayed or arrested alveolar development that translates to a smaller alveolar surface area (SA). Histological morphometry is the gold standard method to measure the SA but requires invasive tissue sampling or the removal of the whole organ for analysis. Alternatively, the SA could be measured in living subjects by "functional morphometry" using Fick's first law of diffusion and noninvasive measurements of the ventilation to perfusion ratio (V̇a/Q̇). We herein aim to describe a novel functional morphometric method to measure SA using a premature baboon model. We used both functional morphometry and postmortem histological morphometry to measure SA in 11 premature baboons born at 135 days who received intensive care treatment for 14 days. For the calculation of the SA by functional morphology, we measured the septal wall thickness using microscopy, the alveolar arterial oxygen gradient using concurrent measurements of arterial pressure of O2 and CO2, and pulmonary perfusion using echocardiography and integrated Doppler signals. The median [interquartile range (IQR)] SA using functional morphometry was 3,100 (2,080-3,640) cm2 and using histological morphometry was 1,034 (634-1,210) cm2 (left lung only). The SA measured by functional morphometry was not related to the SA measured by histological morphometry. Following linear regression analysis, the V̇a/Q̇ significantly predicted the histologically measured SA (R2 = 0.659, P = 0.002). In conclusion, functional measurements of ventilation to perfusion ratio could be used to estimate the alveolar surface area in prematurely born baboons and the ventilation perfusion ratio was the main determinant of the alveolar surface area.NEW & NOTEWORTHY The main morphological characteristic of chronic respiratory disease in prematurely born infants is the impaired/arrested alveolar growth that corresponds to a smaller aggregated alveolar surface area (SA). This decreased SA might be the limiting factor later in life affecting exercise capacity and quality of life. There is paucity of sensitive, noninvasive biomarkers to monitor the evolution of neonatal respiratory disease. Our noninvasive functional morphometric SA might help to bridge the gap between pathophysiology and clinical monitoring.

Relationship between circulating platelet counts and ductus arteriosus patency after indomethacin treatment.

OBJECTIVE: To determine whether low platelet counts are related to the incidence of patent ductus arteriosus (PDA) after indomethacin treatment in preterm human infants. STUDY DESIGN: Multivariable logistic regression modeling was used for a cohort of 497 infants, who received indomethacin (within 15 hours of birth). RESULTS: Platelet counts were not related to the incidence of permanent closure after indomethacin constriction. There was a relationship between platelet counts and the initial degree of constriction; however, this relationship appeared to be primarily influenced by the high end of the platelet distribution curve. PDA incidence was similar in infants with platelet counts < 50 × 109/L and those with platelet counts above this range. Only when platelet counts were consistently >230 ×109/L was there a decrease in PDA incidence. CONCLUSION: In contrast to the evidence in mice, low circulating platelet counts do not affect permanent ductus closure (or ductus reopening) in human preterm infants.

The effects of postnatal estrogen therapy on brain development in preterm baboons.

OBJECTIVE: Estrogen receptors are present within the fetal brain, suggesting that estrogens may exert an influence on cerebral development. Loss of placentally derived estrogen in preterm birth may impair development. STUDY DESIGN: Baboons were delivered at 125 days of gestation (term approximately 185 days), randomly allocated to receive estradiol (n = 10) or placebo (n = 8), and ventilated for 14 days. Brains were assessed for developmental and neuropathological parameters. RESULTS: Body and brain weights were not different between groups, but the brain/body weight ratio was increased (P < .05) in estradiol-treated animals. There were no differences (P > .05) between groups in any neuropathological measure in either the forebrain or cerebellum. There were no intraventricular hemorrhages; 1 estradiol animal displayed ectactic vessels in the subarachnoid space. CONCLUSION: Brief postnatal estradiol administration to primates does not pose an increased risk of injury or impaired brain development.

Patent ductus arteriosus ligation alters pulmonary gene expression in preterm baboons.

Ibuprofen-induced ductus closure improves pulmonary mechanics and increases alveolar surface area in premature baboons compared with baboons with a persistent patent ductus arteriosus (PDA). Ibuprofen-treatment has no effect on the expression of genes that regulate pulmonary inflammation but does increase the expression of alpha-ENaC (the transepithelial sodium channel that is critical for alveolar water clearance). Although ligation eliminates the PDA, it does not improve pulmonary mechanics or increase alveolar surface area. We used preterm baboons (delivered at 67% of term gestation and ventilated for 14 d) to study whether the lack of beneficial effects, after PDA ligation, might be due to alterations in pulmonary gene expression. We found no differences in ventilation or oxygenation indices between animals that were ligated (n = 7) on day of life 6 and those that had a persistent PDA (n = 12) during the entire 14 d study. In contrast with no intervention, PDA ligation produced a significant increase in the expression of genes involved with pulmonary inflammation (COX-2, TNF-α, and CD14) and a significant decrease in alpha-ENaC sodium channel expression. We speculate that these changes may decrease the rate of alveolar fluid clearance and contribute to the lack of improvement in pulmonary mechanics after PDA ligation.

Anatomic closure of the premature patent ductus arteriosus: The role of CD14+/CD163+ mononuclear cells and VEGF in neointimal mound formation.

Permanent closure of the newborn ductus arteriosus requires the development of neointimal mounds to completely occlude its lumen. VEGF is required for neointimal mound formation. The size of the neointimal mounds (composed of proliferating endothelial and migrating smooth muscle cells) is directly related to the number of VLA4 mononuclear cells that adhere to the ductus lumen after birth. We hypothesized that VEGF plays a crucial role in attracting CD14/CD163 mononuclear cells (expressing VLA4) to the ductus lumen and that CD14/CD163 cell adhesion to the ductus lumen is important for neointimal growth. We used neutralizing antibodies against VEGF and VLA-4 to determine their respective roles in remodeling the ductus of premature newborn baboons. Anti-VEGF treatment blocked CD14/CD163 cell adhesion to the ductus lumen and prevented neointimal growth. Anti-VLA-4 treatment blocked CD14/CD163 cell adhesion to the ductus lumen, decreased the expression of PDGF-B (which promotes smooth muscle migration), and blocked smooth muscle influx into the neointimal subendothelial space (despite the presence of increased VEGF in the ductus wall). We conclude that VEGF is necessary for CD14/CD163 cell adhesion to the ductus lumen and that CD14/CD163 cell adhesion is essential for VEGF-induced expansion of the neointimal subendothelial zone.

Highly conserved transcriptional responses to mechanical ventilation of the lung.

Cross-species analysis of microarray data has shown improved discriminating power between healthy and diseased states. Computational approaches have proven effective in deciphering the complexity of human disease by identifying upstream regulatory elements and the transcription factors that interact with them. Here we used both methods to identify highly conserved transcriptional responses during mechanical ventilation, an important therapeutic treatment that has injurious side effects. We generated control and ventilated whole lung samples from the premature baboon model of bronchopulmonary dysplasia (BPD), processed them for microarray, and combined them with existing whole lung oligonucleotide microarray data from 85 additional control samples from mouse, rat, and human and 19 additional ventilated samples from mouse and rat. Of the 2,531 orthologs shared by all 114 samples, 60 were modulated by mechanical ventilation [false discovery rate (FDR)-adjusted q value (q(FDR)) = 0.005, ANOVA]. These included transcripts encoding the transcription factors ATF3 and FOS. Because of compelling known roles for these transcription factors, we used computational methods to predict their targets in the premature baboon model of BPD, which included elastin (ELN), gastrin-releasing polypeptide (GRP), and connective tissue growth factor (CTGF). This approach identified highly conserved transcriptional responses to mechanical ventilation and may facilitate identification of therapeutic targets to reduce the side effects of this valuable treatment.

Ibuprofen treatment for closure of patent ductus arteriosus is not associated with increased risk of neuropathology.

Ibuprofen is an effective pharmacological intervention for closure of a patent ductus arteriosus (PDA) in preterm infants and is an alternative to surgical ligation; however, it is not certain whether ibuprofen treatment is associated with adverse effects on the brain. Therefore, this study examined neuropathological outcomes of ibuprofen therapy for a PDA. Fetal baboons were delivered at 125 d of gestation (dg; term ∼185 dg) by caesarean section, given surfactant, and ventilated for 14 d with positive pressure ventilation (PPV). Baboons were randomly allocated to receive either ibuprofen (PPV+ ibuprofen, n = 8) or no therapy (PPV, n = 5). Animals were killed on day 14 and brains assessed for cerebral growth, development, and neuropathology. Body and brain weights, the total volume of the brain, and the surface folding index (measure of brain growth) were not different (p > 0.05) between PPV+ ibuprofen-treated and PPV animals. There was no difference (p > 0.05) in the number of myelin basic protein-immunoreactive (IR) oligodendrocytes, glial fibrillary acid protein-IR astrocytes, or Iba1-IR macrophages/microglia in the forebrain. No overt cerebellar alterations were observed in either group. Ibuprofen treatment for PDA closure in the preterm baboon neonate is not associated with any increased risk of neuropathology or alterations to brain growth and development.

Patterns of gene expression in the ductus arteriosus are related to environmental and genetic risk factors for persistent ductus patency.

Three independent risk factors (immature gestation, absence of antenatal glucocorticoid exposure, and presence of the rs2817399(A) allele of the gene TFAP2B) are associated with patent ductus arteriosus (PDAs) that fail to close during prostaglandin inhibition. We hypothesized that these three factors may affect a common set of genes that increase the risk of persistent PDA after birth. We studied baboon ductus from term, preterm, and glucocorticoid-treated preterm fetuses and found that both immature gestation and absence of antenatal glucocorticoid exposure decreased RNA expression of calcium- and potassium-channel genes involved in oxygen-induced constriction, and phosphodiesterase genes (that modulate cAMP/cGMP signaling). Ductus obtained from second trimester human pregnancies were genotyped for TFAP2B polymorphisms. When present, the rs2817399(A) allele also was associated with decreased expression of calcium- and potassium-channel genes. In contrast, alleles of two other TFAP2B polymorphisms, rs2817419(G) and rs2635727(T), which are not related to the incidence of PDA after birth, had no effect on RNA expression. In conclusion, three calcium- and potassium-channel genes (CACNA1G/ alpha1G, CACNB 2/CaL-beta2, and KCNA2/ Kv1.2) were similarly affected by each of the PDA risk factors. We speculate that these channels may play a significant role in closing the preterm ductus during prostaglandin inhibition and may be potential targets for future pharmacologic manipulations.

Postnatal estradiol up-regulates lung nitric oxide synthases and improves lung function in bronchopulmonary dysplasia.

RATIONALE: Nitric oxide (NO) plays an important role in lung development and perinatal lung function, and pulmonary NO synthases (NOS) are decreased in bronchopulmonary dysplasia (BPD) following preterm birth. Fetal estradiol levels increase during late gestation and estradiol up-regulates NOS, suggesting that after preterm birth estradiol deprivation causes attenuated lung NOS resulting in impaired pulmonary function. OBJECTIVE: To test the effects of postnatal estradiol administration in a primate model of BPD over 14 days after delivery at 125 days of gestation (term = 185 d). METHODS: Cardiopulmonary function was assessed by echocardiography and whole body plethysmography. Lung morphometric and histopathologic analyses were performed, and NOS enzymatic activity and abundance were measured. MEASUREMENTS AND MAIN RESULTS: Estradiol caused an increase in blood pressure and ductus arteriosus closure. Expiratory resistance and lung compliance were also improved, and this occurred before spontaneous ductal closure. Furthermore, both oxygenation and ventilation indices were improved with estradiol, and the changes in lung function and ventilatory support requirements persisted throughout the study period. Whereas estradiol had negligible effect on indicators of lung inflammation and on lung structure assessed after the initial 14 days of ventilatory support, it caused an increase in lung neuronal and endothelial NOS enzymatic activity. CONCLUSIONS: In a primate model of BPD, postnatal estradiol treatment had favorable cardiovascular impact, enhanced pulmonary function, and lowered requirements for ventilatory support in association with an up-regulation of lung NOS. Estradiol may be an efficacious postnatal therapy to improve lung function and outcome in preterm infants.

Extracorporeal Life Support in Pediatric Patients with Bronchopulmonary Dysplasia and Associated Pulmonary Hypertension.

This retrospective study reviews outcomes of 281 pediatric patients with bronchopulmonary dysplasia (BPD) managed with extracorporeal life support (ECLS). Data from 1982 to 2018 from the Extracorporeal Life Support Organization (ELSO) registry were queried for children aged 60 days to 18 years with a prior diagnosis of BPD, and all patients with secondary pulmonary hypertension (PH) were identified. Overall survival of patients with and without PH was 86.7% and 68.0%, respectively (p = 0.23). There was no report of patients with PH before 2004. Patients with BPD + PH were more likely to have associated intraventricular hemorrhage (p = 0.002) and retinopathy of prematurity (p = 0.05), as well as a greater reported use of sildenafil (p = 0.0001) and milrinone (p = 0.008) before ECLS. The most common primary diagnosis in patients with BPD was viral respiratory infection (45.3%) and in patients with BPD + PH was respiratory failure without mention of infection (40.0%). Inotrope use was the most common complication reported (36.7%) with survival of 54.4%. We conclude that data from the ELSO registry demonstrate reasonable survival in both, patients with BPD and BPD + PH. Thus, patients with BPD and associated PH should be considered candidates for ECLS.

Oxygen-induced tension in the sheep ductus arteriosus: effects of gestation on potassium and calcium channel regulation.

Compared with the full-term ductus arteriosus, the premature ductus is less likely to constrict when exposed to postnatal oxygen concentrations. We used isolated fetal sheep ductus arteriosus (pretreated with inhibitors of prostaglandin and nitric oxide production) to determine whether changes in K+ - and CaL-channel activity could account for the developmental differences in oxygen-induced tension. In the mature ductus, KV-channels appear to be the only K+-channels that oppose ductus tension. Oxygen concentrations between (2% and 15%) inhibit KV-channel activity, which increases the CaL-channel-mediated increase in tension. Low oxygen concentrations have a direct inhibitory effect on CaL-channel activity in the immature ductus; this is not the case in the mature ductus. In the immature ductus, three different K+-channel activities (KV, KCa, and KATP) oppose ductus tension and contribute to its decreased tone. Oxygen inhibits the activities of all three K+ -channels. The inhibitory effects of the three K+-channel activities decline with advancing gestation. The decline in K+ -channel activity is not due to decreased K+ -channel expression. Super-physiologic oxygen concentrations (>or=30% O2) constrict the ductus by using calcium-dependent pathways that are independent of K+- and CaL-channel activities. Super-physiologic oxygen concentrations eliminate the difference in tensions between the two age groups.