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Background: Globally, one in ten babies is born preterm (<37 weeks), and 1-2% preterm at very low birth weight (VLBW, <1500 g). As adults, they are at increased risk for a plethora of health conditions, e.g., cardiometabolic disease, which may partly be mediated by epigenetic regulation. We compared blood DNA methylation between young adults born at VLBW and controls., Methods: 157 subjects born at VLBW and 161 controls born at term, from the Helsinki Study of Very Low Birth Weight Adults, were assessed for peripheral venous blood DNA methylation levels at mean age of 22 years. Significant CpG-sites (5'-C-phosphate-G-3') were meta-analyzed against continuous birth weight in four independent cohorts (pooled n = 2235) with cohort mean ages varying from 0 to 31 years., Results: In the discovery cohort, 66 CpG-sites were differentially methylated between VLBW adults and controls. Top hits were located in HIF3A, EBF4, and an intergenic region nearest to GLI2 (distance 57,533 bp). Five CpG-sites, all in proximity to GLI2, were hypermethylated in VLBW and associated with lower birth weight in the meta-analysis., Conclusion: We identified differentially methylated CpG-sites suggesting an epigenetic signature of preterm birth at VLBW present in adult life., Impact: Being born preterm at very low birth weight has major implications for later health and chronic disease risk factors. The mechanism linking preterm birth to later outcomes remains unknown. Our cohort study of 157 very low birth weight adults and 161 controls found 66 differentially methylated sites at mean age of 22 years. Our findings suggest an epigenetic mark of preterm birth present in adulthood, which opens up opportunities for mechanistic studies., (© 2024. The Author(s).)

Background: Low-grade systemic inflammation measured as high sensitivity C-reactive protein (hs-CRP) has been associated with non-communicable disease risk. We assessed whether prenatal inflammation and early-childhood vitamin D are associated with inflammation until age 6-8., Methods: We analyzed blood hs-CRP and 25-hydroxy vitamin D [25(OH)D] in pregnancy, at birth from umbilical cord blood (UCB), from offspring at ages 1, 2, and 6-8 years in the Vitamin D Intervention in Infants (VIDI) study. VIDI was a randomized-controlled trial of vitamin D supplementation of 10 μg/day or 30 μg/day from age 2 weeks until 2 years in 975 infants recruited in 2013-14, with follow-up at age 6-8 in 2019-21 (n = 283)., Results: Pregnancy hs-CRP was associated with UCB hs-CRP (r = 0.18, p < 0.001) but not independently with childhood hs-CRP (Estimate [95% CI] 0.04 [<-0.00, 0.09]). Higher UCB hs-CRP was associated independently with higher hs-CRP until 6-8 years (0.20 [0.12, 0.29]). Infant vitamin D dose had no effect on longitudinal hs-CRP (6-8 years, 0.11 [-0.04, 0.25]). Childhood 25(OH)D were associated positively with hs-CRP until age 6-8 (0.01 [>0.00, 0.01])., Conclusion: Our results indicate that in children, inflammation, assessed by hs-CRP, persists from birth until 6-8 years. We observed positive associations between 25(OH)D and hs-CRP in vitamin D-sufficient children., Impact: High sensitivity C-reactive protein (hs-CRP) concentrations tract from birth to age 8 years Our novel finding suggests a long-lasting pro-inflammatory phenotype in the child Higher vitamin D concentration - but not dose - is associated with higher childhood hs-CRP Chronic disease risk related to inflammation may in part originate from the prenatal period or early childhood Further studies are needed to investigate the effects of inflammation on long-term clinical health outcomes., (© 2024. The Author(s).)

Background: Studies on body composition in preterm very low birth weight (VLBW < 1500 g) survivors are inconsistent and trajectories later in life unknown. We assessed body composition and its change from young to mid-adulthood in VLBW adults., Methods: We studied 137 VLBW adults and 158 term-born controls from two birth cohorts in Finland and Norway at mean age 36 years. Body composition was assessed by 8-polar bioelectrical impedance. We compared results with dual-energy x-ray absorptiometry measurements at 24 years., Results: In mid-adulthood, VLBW women and men were shorter than controls. Fat percentage (mean difference in women 1.1%; 95% CI, -1.5% to 3.5%, men 0.8%; -2.0% to 3.6%) and BMI were similar. VLBW women had 2.9 (0.9 to 4.8) kg and VLBW men 5.3 (2.7 to 8.1) kg lower lean body mass than controls, mostly attributable to shorter height. Between young and mid-adulthood, both groups gained fat and lean body mass (p for interaction VLBW x age>0.3)., Conclusion: Compared with term-born controls, VLBW adults had similar body fat percentage but lower lean body mass, largely explained by their shorter height. This could contribute to lower insulin sensitivity and muscular fitness previously found in VLBW survivors and predispose to functional limitations with increasing age., Impact: In mid-adulthood, individuals born preterm with very low birth weight had similar body fat percentage but lower lean body mass than those born at term. This was largely explained by their shorter height. First study to report longitudinal assessments of body size and composition from young to mid-adulthood in very low birth weight adults. Lower lean body mass in very low birth weight adults could contribute to lower insulin sensitivity and muscular fitness and lead to earlier functional limitations with increasing age., (© 2023. The Author(s).)

Background: Caffeine is widely used in preterm infants for apnea control. It has no effect on sleep in the only existing polysomnographic study including ten preterm infants Behavioral and polygraphic studies have conflicting results., Methods: We studied 21 late-preterm infants at a median gestational age of 36 weeks. Polysomnography was performed twice, at baseline on day 1 and on the day after the onset of caffeine treatment (20 mg/kg loading and 5 mg/kg morning maintenance dose)., Results: Caffeine acted short term as a breathing stimulant with reduction of apneas, improved baseline SpO 2 (p < 0.001), and decreased 95 percentile of end-tidal carbon dioxide level (p < 0.01). It also increased arousal frequency to SpO 2 desaturations of more than 5% (p < 0.001). Caffeine did not affect sleep stage distribution, sleep efficiency, frequency of sleep stage transitions, appearance of REM periods, or the high number of spontaneous arousals. The median spontaneous arousal count was 18 per hour at baseline, and 16 per hour during caffeine treatment (p = 0.88)., Conclusions: In late-preterm infants, caffeine has a clear short-term respiratory stimulant effect, and it increases the arousal frequency to hypoxia. However, caffeine does not appear to act as a central nervous system stimulant, and it has no acute effect on sleep quality., Impact: Effects of caffeine on sleep in preterm infants has previously been investigated with only one full polysomnographic study including ten preterm infants. The study showed no effect. The current study shows that caffeine acts short term as a respiratory stimulant and increases arousal frequency to hypoxia. Although a potent central nervous system (CNS) stimulant in adults, caffeine does not seem to have similar acute CNS effect in late-preterm infants. The onset of caffeine treatment has no short-term effect on sleep stage distribution, sleep efficiency, frequency of sleep stage transitions, appearance of REM periods, or the high number of spontaneous arousals., (© 2021. The Author(s).)

Background: Extremely low gestational age newborns (ELGANs) are at risk of neurodevelopmental impairments that may originate in early NICU care. We hypothesized that early oxygen saturations (SpO 2 ), arterial pO 2 levels, and supplemental oxygen (FiO 2 ) would associate with later neuroanatomic changes., Methods: SpO 2 , arterial blood gases, and FiO 2 from 73 ELGANs (GA 26.4 ± 1.2; BW 867 ± 179 g) during the first 3 postnatal days were correlated with later white matter injury (WM, MRI, n = 69), secondary cortical somatosensory processing in magnetoencephalography (MEG-SII, n = 39), Hempel neurological examination (n = 66), and developmental quotients of Griffiths Mental Developmental Scales (GMDS, n = 58)., Results: The ELGANs with later WM abnormalities exhibited lower SpO 2 and pO 2 levels, and higher FiO 2 need during the first 3 days than those with normal WM. They also had higher pCO 2 values. The infants with abnormal MEG-SII showed opposite findings, i.e., displayed higher SpO 2 and pO 2 levels and lower FiO 2 need, than those with better outcomes. Severe WM changes and abnormal MEG-SII were correlated with adverse neurodevelopment., Conclusions: Low oxygen levels and high FiO 2 need during the NICU care associate with WM abnormalities, whereas higher oxygen levels correlate with abnormal MEG-SII. The results may indicate certain brain structures being more vulnerable to hypoxia and others to hyperoxia, thus emphasizing the role of strict saturation targets., Impact: This study indicates that both abnormally low and high oxygen levels during early NICU care are harmful for later neurodevelopmental outcomes in preterm neonates. Specific brain structures seem to be vulnerable to low and others to high oxygen levels. The findings may have clinical implications as oxygen is one of the most common therapies given in NICUs. The results emphasize the role of strict saturation targets during the early postnatal period in preterm infants., (© 2021. The Author(s).)

Background: Antenatal glucocorticoids (GCs) reduce respiratory distress syndrome (RDS) in preterm infants and are associated with reduced lung liquid content. Our aim was to assess whether airway gene expression of mediators of pulmonary epithelial sodium and liquid absorption, and further, respiratory morbidity, associate with cord blood GC concentrations., Methods: The study included 64 infants delivered <32 weeks gestation. Cortisol and betamethasone in umbilical cord blood were quantified with liquid chromatography-tandem mass spectrometry. The total GC concentration was calculated. Gene expression of the epithelial sodium channel (ENaC), Na,K-ATPase, and serum- and GC-inducible kinase 1 at <2 h and at 1 day postnatally in nasal epithelial cell samples was quantified with reverse transcription-polymerase chain reaction. The mean oxygen supplementation during the first 72 h was calculated., Results: Concentrations of cord blood betamethasone and total GC were significantly lower in infants with RDS and correlated with mean oxygen supplementation. Expression of αENaC and α1- and β1Na,K-ATPase at <2 h correlated with betamethasone and total GC concentrations. Expression of Na,K-ATPase was lower in infants with RDS., Conclusion: Enhancement of lung liquid absorption via increased expression of sodium transporters may contribute to the beneficial pulmonary effects of antenatal GCs., Impact: RDS is related to lower umbilical cord blood GC concentrations and lower airway expression of sodium transporters. In addition to the timing of antenatal GC treatment, resulting concentrations may be of importance in preventing RDS. Induction of sodium transport may be a factor contributing to the pulmonary response to antenatal GCs.

Background: The significance of arousal in apnea termination in preterm infants is not known., Methods: We investigated the appearance of arousals from sleep with polysomnography for 21 preterm infants at a median age of 36 gestational weeks., Results: The polysomnographic appearance of sleep was fragmented by frequent arousals. The number of spontaneous arousals unrelated to apneas was 18 per hour in sleep; higher in rapid eye movement (REM) sleep than in non-REM sleep (p < 0.001). Eighty-two percent of arousals were regarded as spontaneous, and 18% were related to apneas. In turn, arousal followed 5% of all apneas; 30% of mixed, 2% of central, and 20% of long apneas defined as apnea of prematurity. Apneas without an arousal led to lower oxygen saturation levels than those followed by an arousal (p < 0.001). Mixed apneas with an arousal had stronger breathing effort and a higher number of breaths compared with apneas without an arousal (p < 0.05)., Conclusions: In preterm infants, frequent spontaneous arousals or arousal-type phenomena make the polysomnographic appearance of sleep fragmented. However, even long apneas or hypoxia commonly fail to elicit arousals or any sign of sleep interruption. Our findings suggest that arousal appears not to be the main mechanism for apnea termination in preterm infants., Impact: Polysomnographic appearance of sleep in preterm infants is fragmented by arousals. Contrary to older children and adults, arousal to apnea is uncommon in preterm infants. Even long mixed apneas with desaturation mostly fail to elicit an arousal response. In preterm infants, apnea termination appears not to depend on an arousal. Low arousability is suggested to be caused by a low ventilation response to hypoxia.

Background: Endogenous pulmonary stem cells (PSCs) play an important role in lung development and repair; however, little is known about their role in bronchopulmonary dysplasia (BPD). We hypothesize that an endogenous PSC marker stage-specific embryonic antigen-1 (SSEA-1) and its enzyme, α1,3-fucosyltransferase IX (FUT9) play an important role in decreasing inflammation and restoring lung structure in experimental BPD., Methods: We studied the expression of SSEA-1, and its enzyme FUT9, in wild-type (WT) C57BL/6 mice, in room air and hyperoxia. Effects of intraperitoneal administration of recombinant human FUT9 (rhFUT9) on lung airway and parenchymal inflammation, alveolarization, and apoptosis were evaluated., Results: On hyperoxia exposure, SSEA-1 significantly decreased at postnatal day 14 in hyperoxia-exposed BPD mice, accompanied by a decrease in FUT9. BPD and respiratory distress syndrome (RDS) in human lungs showed decreased expression of SSEA-1 as compared to their term controls. Importantly, intraperitoneal administration of FUT9 in the neonatal BPD mouse model resulted in significant decrease in pulmonary airway (but not lung parenchymal) inflammation, alveolar-capillary leakage, alveolar simplification, and cell death in the hyperoxia-exposed BPD mice., Conclusions: An important role of endogenous PSC marker SSEA-1 and its enzyme FUT9 is demonstrated, indicating early systemic intervention with FUT9 as a potential therapeutic option for BPD., Impact: Administration of rhFUT9, an enzyme of endogenous stem cell marker SSEA-1, reduces pulmonary airway (but not lung parenchymal) inflammation, alveolar-capillary leak and cell death in the BPD mouse model. SSEA-1 is reported for the first time in experimental BPD models, and in human RDS and BPD. rhFUT9 treatment ameliorates hyperoxia-induced lung injury in a developmentally appropriate BPD mouse model. Our results have translational potential as a therapeutic modality for BPD in the developing lung.

Background: Vitamin D is a potent immunomodulator and may play a role in the development of the fetal innate immune functions. The aim of our study was to evaluate inflammatory markers in cord blood of healthy newborns in relation to vitamin D status at birth., Methods: We studied the concentrations of inflammatory markers, matrix metalloproteinase 8 (MMP-8) and high sensitivity CRP (hs-CRP), and 25-hydroxyvitamin D (25(OH)D) in cord blood of 939 healthy term infants born to mothers of Caucasian origin. We evaluated perinatal factors that affect the concentrations of MMP-8 and hs-CRP, and further explored associations between cord blood 25(OH)D and these inflammatory biomarkers., Results: Majority (99%) of the cohort was vitamin D sufficient (>50 nmol/l or 20 ng/ml). We observed a positive correlation between cord blood 25(OH)D and MMP-8 concentrations, and between 25(OH)D and hs-CRP concentrations. After adjustment for potential confounders (parity, antenatal antibiotic treatment, gestational age, mode of delivery, and maternal prepregnancy BMI), the association of 25(OH)D with MMP-8 and hs-CRP remained significant., Conclusion: Cord blood 25(OH)D correlates with inflammatory markers MMP-8 and hs-CRP. The findings may reflect the diverse immunomodulatory functions of vitamin D in the innate immune response of the newborn.

Background: Late-preterm birth (at 34 0⁄7 -36 6⁄7 wk gestation) increases the risk of early growth faltering, poorer neurocognitive functioning, and lower socio-economic attainment. Among early-preterm individuals, faster early growth benefits neurodevelopment, but it remains unknown whether these benefits extend to late-preterm individuals., Methods: In 108 late-preterm individuals, we examined if weight, head, or length growth between birth, 5 and 20 months' corrected age, and 56 mo, predicted grade point average and special education in comprehensive school, or neurocognitive abilities and psychiatric diagnoses/symptoms at 24-26 y of age., Results: For every 1 SD faster weight and head growth from birth to 5 mo, and head growth from 5 to 20 mo, participants had 0.19-0.41 SD units higher IQ, executive functioning score, and grade point average (95% confidence intervals (CI) 0.002-0.59 SD), and lower odds of special education (odds ratio (OR) = 0.49-0.59, 95% CIs 0.28-0.97), after adjusting for sex, gestational age, follow-up age, and parental education. Faster head growth from 20 to 56 mo was associated with less internalizing problems; otherwise we found no consistent associations with mental health outcomes., Conclusion: Faster growth during the critical early period after late-preterm birth is associated with better adult neurocognitive functioning, but not consistently with mental health outcomes.

Background: Higher cortical function during sensory processing can be examined by recording specific somatosensory-evoked magnetic fields (SEFs) with magnetoencephalography (MEG). We evaluated whether, in extremely low-gestational-age (ELGA) infants, abnormalities in MEG-recorded SEFs at term age are associated with adverse neurodevelopment at 2 y of corrected age., Methods: SEFs to tactile stimulation of the index finger were recorded at term age in 30 ELGA infants (26.5 ± 1.2 wk, birth weight: 884 g ± 181 g). Neurodevelopment was evaluated at 2 y of corrected age. Controls were 11 healthy term infants., Results: In nine of the ELGA infants (30.0%), SEFs were categorized as abnormal on the basis of lack of response from secondary somatosensory cortex (SII). At 2 y, these infants had a significantly worse mean developmental quotient and locomotor subscale on the Griffiths Mental Development Scales than the ELGA infants with normal responses. Mild white matter abnormalities in magnetic resonance imaging at term age were detected in 21% of infants, but these abnormalities were not associated with adverse neurodevelopment., Conclusion: Abnormal SII responses at term predict adverse neuromotor development at 2 y of corrected age. This adverse development may not be foreseen with conventional neuroimaging methods, suggesting a role for evaluating SII responses in the developmental risk assessment of ELGA infants.

Background: As a protective response to an inflammatory stimulus, the antigen-presenting molecules (human leukocyte antigen-DR (HLA-DR)) on monocytes are downregulated. If severe, the response may lead to immunodepression or immunoparalysis, associated with an increased rate of morbidity and mortality in adults. In very low birth weight (VLBW) infants, birth and intensive care present major immunological challenges., Methods: We measured monocyte HLA-DR expression by flow cytometry and determined 13 plasma cytokines in 56 VLBW infants (gestational age (GA): 23.7-31.8 wk) and 25 controls (GA: 34.1-41.4 wk)., Results: HLA-DR expression decreased postnatally both in VLBW and in control infants. In VLBW infants, GA and respiratory distress syndrome (RDS) both showed associations with HLA-DR nadir on day 3, when 45% of them met the criteria of immunodepression. HLA-DR expression was lower in those infants subsequently developing infection (74 vs. 49% (day 3) and 85 vs. 68% (day 7); both P = 0.002). Interleukin (IL)-6 on day 1 was a predictor of the HLA-DR nadir., Conclusion: VLBW infants are in a state of immunodepression postnatally. This immunodepression correlated with GA and was a predisposing factor for late infections. The downregulation of HLA-DR during RDS probably indicates an RDS-induced antigen load on the immune system.

This study was set out to develop and describe a novel, simple, and safe method for routine bedside testing of somatosensory system in very early preterm infants. We recorded electroencephalogram (EEG) activity after tactile stimulation of hand (palm) and foot (sole) by a soft hairbrush stimulator in extremely low birth weight infants (n = 10; GA, 24-28, recording at conceptional age 30-32 wk) and compared with the raw EEG responses to those seen by one- or two-channel brain monitors. In every subject, single tactile stimuli produced prominent (100-350 microV) somatosensory evoked responses (SERs) that were readily identified in the ongoing EEG signal. The maximal SER was in the contralateral hemisphere at around the corresponding somatosensory representation areas. Conventional EEG filtering did significantly reduce the SERs, but they could still be identified in the routine brain monitor setting widely available in NICUs. The method described here is directly applicable to assessment of integrity of somatosensory system in the early preterm period. It needs minimal training and requires an EEG system or a brain monitor device that is available in most units. Thus, the technique is likely to open a novel window to neurologic assessment of these babies.

Vestibulo-mediated cardiovascular control in hazardous situations is important. Our hypothesis is that the prerequisite for sudden infant death syndrome (SIDS) is impaired vestibulo-mediated cardiovascular control. Prematurity is a risk factor for SIDS, and postnatal intermittent hypoxia may contribute to this risk. We studied heart rate (HR) and blood pressure (BP) responses in 10 infants with bronchopulmonary dysplasia (BPD) who were born at 27 +/- 2.4 (23-30) wk of gestation. Twenty healthy term infants served as controls. Cardiovascular tests were performed under polysomnographic control during slow-wave sleep (SWS) at a corrected age of 12 +/- 3.5 (7-19) wk. Control infants showed biphasic HR and BP responses to side motion with an immediate increase followed by a modest decrease and return to baseline. Compared with the controls, half of the BPD infants had altered BP responses (p < 0.005) without an early increase, followed by a more prominent decrease in BP. BPD infants also presented with a greater variability in BP responses to head-up tilts than did the controls (p < 0.001). In conclusion, these findings suggest that some BPD infants have impaired vestibular sympathoreflex-mediated cardiovascular control. This dysfunction may become critical in life-threatening situations.

Acute lung injury is marked by damage to alveolar-capillary barrier. High pulmonary levels of matrix-degrading serine proteinase trypsin and matrix metalloproteinases (MMP)-2, -8, and -9 have been shown in preterm infants with respiratory distress syndrome (RDS). We studied expression of trypsin and MMP-2, -8, and -9 in rats exposed to >95% oxygen for 24, 48, or 60 h. As demonstrated by zymography and Western immunoblotting, levels of trypsin and MMP-2, -8, and -9 in bronchoalveolar lavage fluid (BALF) sharply increased after 48 h of hyperoxia relative to normoxia controls. This coincided with increase in alveolar-capillary permeability, as indicated by increased protein concentration in BALF. Both neutrophil-derived 80-kD and mesenchymal cell-derived 60-kD MMP-8 isoforms were detected in BALF. Of them, mesenchymal-type MMP-8 predominated. In immunohistochemistry, alveolar epithelium showed strong trypsin expression at 48 and 60 h of hyperoxia, whereas it was predominantly negative in controls. MMP-8 was mostly expressed in macrophages. Marked up-regulation of trypsin and MMP-8 early during hyperoxic lung injury suggests that these enzymes play a role in the pathogenesis of acute lung injury and may therefore be potential targets for therapy of lung injury.

The placental enzyme 11beta-hydroxysteroid dehydrogenase-2 (11beta-HSD2) transforms maternal cortisol to inactive cortisone. Fetal glucocorticoid excess due to reduced 11beta-HSD2 activity could make small preterm infants susceptible to early adrenal insufficiency when the maternal cortisol source is no longer sustained. We assessed whether placental 11beta-HSD2 activity is related to early adrenal insufficiency and postnatal clinical course in extremely low birth weight (<1000 g) infants. Mean gestational age of the 44 infants was 26.6 wk (range, 23.7-32.0), birth weight was 747 g (440-981), and relative birth weight was -1.9 SD (-4.9 to 1.0). We determined placental 11beta-HSD2 activity, baseline, and ACTH-stimulated cortisol and assessed illness severity by the Score of Neonatal Acute Physiology (SNAP). One standard deviation decrease in placental 11beta-HSD2 activity corresponded to a 1.85 (95% CI 0.55 to 3.14; p = 0.006) unit increase in SNAP score and 2.9 mm Hg decrease in minimum mean arterial pressure (95% CI 0.3 to 5.6 mm Hg; p = 0.03). Placental 11beta-HSD2 activity was not associated with cortisol concentrations, although the confidence interval of the ACTH-stimulated cortisol was close to zero: 1 SD increase corresponded to 17% (-18% to 49%) increase in ACTH-stimulated cortisol. Moreover, a 1 SD decrease in enzyme activity was associated with a hazard ratio for postnatal glucocorticoid treatment of 1.63 (95% CI 1.00 to 2.65); p = 0.05. In ELBW infants, lower placental 11beta-HSD2 activity is associated with more severe early postnatal illness and hypotension. Although an association with baseline or ACTH-stimulated cortisol was not seen, possible relationships with other components of the hypothalamic-pituitary-adrenal axis remain to be determined.

Proteinase-activated receptor 2 (PAR(2)), a G-protein-coupled receptor activated by serine proteinases such as trypsin, has been suggested to play an important role in inflammatory and fibroproliferative processes. In preterm infants, the development of bronchopulmonary dysplasia (BPD) is characterized by early pulmonary inflammation and subsequent interstitial fibrosis. High pulmonary trypsin-2 has been shown to be associated with the development of BPD. We studied the expression and distribution of PAR(2) and trypsin-2 by immunohistochemistry in autopsy lung specimens of fetuses (n = 10), of preterm infants who died of acute or prolonged respiratory distress syndrome (RDS) (n = 8 and n = 7, respectively) or BPD (n = 6), and of newborn infants without lung disease (n = 5) who served as controls. In prolonged RDS and BPD, PAR(2) immunoreactivity was significantly higher in bronchial epithelium when compared with infants without pulmonary pathology (p < 0.05 and p < 0.005, respectively). In alveolar epithelium, expression of PAR(2) was elevated in prolonged RDS when compared with newborn infants without pulmonary pathology (p < 0.05). Moreover, strong expression of PAR(2) was detected in myofibroblasts of thickened and fibrotic alveolar walls in prolonged RDS or BPD. Trypsin-2 was co-localized with PAR(2) in bronchoalveolar epithelium. These findings suggest that PAR(2), possibly activated by trypsin-2, may participate in inflammation and fibroproliferation associated with progression of RDS toward BPD in preterm infants.

Late-onset hospital-acquired sepsis is common in extremely low birth-weight (<1000 g) (ELBW) infants. The diagnosis is difficult since, at early stages of sepsis, routine laboratory tests are neither specific nor sensitive. In term infants with sepsis neutrophil surface expression of CD11b/CD18, a beta2-integrin, is significantly increased. Here we studied whether increased CD11b/CD18 density on blood neutrophils and monocytes serves as an early sepsis marker in ELBW infants. Blood samples were obtained from 30 ELBW infants on a daily basis for 3-4 postnatal weeks, and neutrophil and monocyte CD11b/CD18 expression was determined by flow-cytometry. Patients were assigned one of 3 groups: 1) an infected group, comprised of infants who had blood culture-positive sepsis and/or necrotizing enterocolitis, 2) a non-infected group, and 3) a potentially infected group, comprised of infants in whom infection was suspected but could not be confirmed microbiologically. One patient had blood culture contamination and was excluded from the analysis. In the infected group, CD11b expression gradually increased during the three days preceding sampling for blood culture. At the day of sampling, median expression of CD11b in neutrophils and monocytes was higher in the infected group than in the control group. For neutrophils the sensitivity and specificity were 1.00 and 0.56, respectively, and for monocytes, 0.86 and 0.94, respectively. From these data, we conclude that determination of CD11b/CD18 density on neutrophils and monocytes may improve diagnosis of late-onset sepsis in ELBW infants.

Upon activation, polymorphonuclear leucocytes (PMN) release bactericidal/permeability-increasing protein, (BPI) from their azurophil granules. BPI selectively binds to the lipopolysaccharide (LPS) on gram-negative bacteria and induces their death. This study examined plasma BPI concentration levels in healthy newborns and in newborns with clinical sepsis, and the ability of PMN from preterm and term infants to release BPI. We also studied the release of myeloperoxidase (MPO), and the surface expression of adhesion molecule CD11b on PMN. In infants with clinical sepsis, plasma BPI concentration was higher, 27.8 microg/L [8.6-883; median (range)] (n = 11), than in healthy term infants 8.9 microg/L (3.9-179) (n = 17), and in adults 7.3 microg/L (0.7 -18.4) (n = 15); p = 0.014, Kruskal-Wallis. In preterm infants (n = 8), the ability of PMN to release BPI in vitro after stimulation with PMA was 8.8, in term infants it was 15.9 (n = 29; p > 0.05 vs. preterm infants) and in adults 23.4 ng/10(6) PMN (n = 15; p = 0.024 and p > 0.05 vs. preterm and term infants, respectively). The corresponding values of MPO were 20.0 ng/10(6) (11.3-46.7) in preterms, 19.0 ng/10(6) (2.2-223.7) in terms, and 27.8 ng/10(6) (9.1-80.7) in adults; p = 0.67 between groups. In infants with clinical sepsis, CD11b level was higher, 292 RFU (234-403) than the basal CD11b expression levels in healthy newborn infants, 116 RFU (76-145); P = 0.0001. FMLP-stimulated PMN CD11b expressions in preterm cord blood, 1071 RFU (552-1286) and in term cord blood, 918 (567-1472) were on the same level, but lower than that in adult blood, 1592 (973-1946); p < 0.001, ANOVA. Our findings suggest that in preterm infants the ability to release BPI is lower than in adults and term infants. These findings suggest that premature neonates have an impaired ability to mobilize BPI, possibly contributing to their marked susceptibility to infections with Gram-negative bacteria.

Disorders affecting fetal growth are commonly associated with premature birth. IGFs and their binding proteins (IGFBPs) are potent regulators of fetal growth. In vitro evidence suggests that they regulate collagen turnover. Collagen turnover can be monitored by serum markers of type I collagen synthesis (PINP) and degradation (ICTP) and a marker of type III collagen synthesis (PIIINP). We examined whether these markers in fetal circulation reflect intrauterine growth and maturity, and whether any interrelationship exists between them and fetal IGFs and IGFBPs in preterm infants before 32 wk of gestation. Cord plasma PINP, ICTP, PIIINP, IGF-I, IGF-II, IGFBP-1, and IGFBP-3 were determined for 98 preterm infants. To express birth weight in units adjusted for gestational age, a birth weight SD score (SDS) was calculated. Negative correlations existed between gestational age and PINP (r = -0.43; p < 0.0001), ICTP (r = -0.34; p = 0.002), and PIIINP (r = -0.34; p = 0.0001). Positive correlations existed between birth weight SDS and PINP (r = 0.40; p = 0.0002) and ICTP (r = 0.48; p < 0.0001) but not PIIINP. Moreover, birth weight SDS was positively correlated with IGF-I (r = 0.58; p < 0.0001) and IGFBP-3 (r = 0.44; p < 0.0001) and negatively correlated with IGF-II (r = -0.36; p = 0.003) and IGFBP-1 (r = -0.50; p < 0.0001). Gestational age correlated with IGFBP-3 (r = 0.25; p = 0.03). In preeclampsia, IGF-I was lower (p = 0.002) and IGFBP-1 higher (p < 0.0001), also after adjustment for fetal size. The number of antenatal glucocorticoid treatments was associated with lower ICTP (p = 0.04), higher IGF-I (p = 0.002), lower IGF-II (p = 0.02), lower IGFBP-1 (p = 0.05), and higher IGFBP-3 (p = 0.004), also after adjustment for potential confounders. In multiple regression analysis, the factors significantly associated with PINP (R:(2) = 0.47) were gestational age and IGF-I, and those associated with ICTP (R:(2) = 0.54) were IGF-I, gestational age, and antenatal glucocorticoid treatment. We conclude that IGF-I may be involved in regulation of type I collagen turnover in the growing fetus. Cord blood PINP and ICTP reflect both fetal growth and maturity and deserve evaluation as potential indicators of postnatal growth velocity in preterm infants, whereas PIIINP reflects fetal maturity.

Cyclooxygenases-1 and -2 are the key enzymes in the conversion of arachidonic acid to prostanoids. Cyclooxygenase-2 (COX-2) takes part both in inflammation and in control of cell growth. COX-2 immunohistochemistry was performed on lung tissues from autopsies, with four groups included: fetuses (n = 4, GA = 16.0 to 32.0 wk), preterm infants (n = 10, GA = 23.0 to 29.9 wk), term infants (n = 6, GA = 38.7 to 42.0 wk), and infants with bronchopulmonary dysplasia (BPD) (n = 4, GA = 28.9 to 30.7 wk). COX-2 staining occurred exclusively in the epithelial cells resembling type II pneumocytes in the alveolae, and in ciliated epithelial cells in the bronchi. In fetuses, moderate intensity alveolar staining was seen in 90-100% cells lining the alveolar epithelium. In preterm infants, high intensity alveolar staining was seen in a scattered pattern. In term infants, the alveolar staining was also scattered, but with a lower proportion of positive cells. In BPD no staining appeared in alveolar epithelial cells. The most intense bronchial staining was found in fetuses and the least intense in term infants; staining was also seen in BPD. COX-2 is present in human perinatal lung from the gestational age of 16 wk, in a changing pattern. We suggest that COX-2 may, in addition to participating in inflammation, also play a developmental role in the perinatal lung.

There are substantial alterations in fuel homeostasis immediately after birth. Leptin is a putative regulator of energy metabolism. Consequently, the aim of this study was to examine whether there are changes in circulating leptin concentrations during the early postnatal period. Umbilical cord mixed blood samples were taken at delivery, and a venous blood sample was obtained at 3 d of age from 38 healthy newborn infants (20 male, 18 female; gestational age 36.3 to 41.9 wk) for analysis of leptin concentration with radioimmunoassay. Cord plasma leptin concentration was 9.7+/-5.2 microg/L (mean+/-SD), with no gender difference between male (8.6+/-4.6 microg/L) and female (10.9+/-5.6 microg/L) infants. In male newborns, cord plasma leptin concentration correlated with arm circumference (r = 0.48, p < 0.05), and in female newborns with body mass index (r = 0.62, p < 0.01), thickness of the s.c. fat (r = 0.54, p < 0.05), and arm circumference (r = 0.72, p < 0.01). By the third postnatal day, plasma leptin decreased similarly in male (to 1.8+/-0.4 microg/L, p < 0.001) and female (to 2.3+/-0.8 microg/L, p < 0.001) infants, when there was a significant gender difference in leptin levels (p = 0.01). At 3 d of age, plasma leptin correlated with weight (r = 0.49, p < 0.05) and arm circumference (r = 0.49, p < 0.05) in female but not in male newborns. In conclusion, 1) circulating leptin already correlates with adiposity at birth in female but not in male newborn infants and 2) leptin decreases markedly in both genders by the third postnatal day, and the gender difference with higher leptin levels in females develops by that time. Thus, the postnatal decrease in plasma leptin concentration may be a physiologically feasible adaptation to profound alterations in fuel homeostasis during the first days of extrauterine life.

As a model of the meconium aspiration syndrome (MAS) of human infants, adult rabbits and newborn rhesus monkeys received intratracheal instillation of human meconium to induce pulmonary injury. Injured rabbits were ventilated with 100% O2 and divided into four treatment groups, receiving: 1) bronchoalveolar lavages (BAL) with dilute KL4-Surfactant; 2) lavages with equal volumes of sterile saline; 3) a single intratracheal bolus of KL4-Surfactant, 100 mg/kg; and 4) no treatment. The untreated rabbits developed atelectasis, a fall in pressure-volume levels and in partial pressure of O2 in arterial blood (PaO2) from approximately 500 to < 100 mm Hg, and severe pulmonary inflammation between 3 and 5 h after instillation of meconium. Rabbits treated by BAL with dilute KL4-Surfactant showed rapid and sustained recovery of PaO2 to approximately 300 mm Hg within minutes, a return toward normal pressure-volume levels, and diminished inflammation. Rabbits receiving BAL with saline failed to show recovery, and rabbits treated with a bolus of surfactant intratracheally exhibited a transient response by 1-2 h after treatment, but then returned to the initial atelectatic state. Newborn rhesus monkeys, after receiving human meconium intratracheally before the first breath, developed severe loss of pulmonary function. Treatment of these monkeys 1-5 h after birth with BAL with dilute KL4-Surfactant produced clearing of chest radiographs and a rapid improvement in pulmonary function with ratios of partial pressure of O2 in arterial blood to the fraction of O2 in the inspired air rising into the normal range where they remained through the 20-h period of study. The studies indicate that pulmonary function in two models of severe meconium injury respond rapidly to BAL with dilute KL4-Surfactant.

To examine the role of immaturity in the free radical-mediated rate of lipid peroxidation in premature infants, we studied 27 infants [gestational age, 27.1 (SD 2.4) wk; birth weight, 970 (SD 330) g]. Ethane and pentane were quantitated in expired air during the first 18 d of life. During the first 2 postnatal d ethane [24.1 (SEM 7.8) pmol x kg-1 x min-1] and pentane [24.2 (SEM 4.1) pmol x kg-1 x min-1] were stable but increased during d 5 to maxima of 79.1 (15.8) pmol x kg-1 x min-1 and 62.1 (8.1) pmol x kg-1 x min-1, respectively. Maximum ethane and pentane correlated with gestational age (r = -0.42, p = 0.03 and r = -0.52, p = 0.005, respectively) and birth weight (r = -0.38, p = 0.05 and r = -0.59, p = 0.001, respectively). Infants with high maximum expired ethane and pentane (exceeding 40 pmol x kg-1 x min-1) had higher odds of dying or having bronchopulmonary dysplasia than those with low ethane and pentane (odds ratio, 6.5; 95% confidence interval, 1.1 to 38.5; p < 0.05 for ethane and odds ratio, 5.6; 95% confidence interval, 1.1 to 29.3; p < 0.05 for pentane). We conclude that degree of prematurity is the single most important factor explaining free radical-mediated lipid peroxidation in premature infants. A therapeutic intervention to limit the effects of free radicals should be started during the 1st postnatal d in premature infants to be effective.

Lipid emulsions used in parenteral nutrition are prone to peroxidation that may be an important feature of oxygen-associated tissue damage. Incubation of lipid emulsion [Intralipid (IL)] with H2O2 and FeCl2 increased lipid peroxidation, measurable as increased production of pentane, from 0.39 +/- 0.33 to 0.99 +/- 0.18 microM (p less than 0.0001). Malondialdehyde was increased from 0.010 +/- 0.005 mM to 0.380 +/- 0.025 mM (p less than 0.001). Superoxide dismutase and catalase (each 100 U/mL) or vitamin C (10 mM) inhibited pentane and malondialdehyde production (p less than 0.0001). Incubation of human erythrocytes in the presence of FeCl2 caused 11.0 +/- 3.2% hemolysis (control 0.95 +/- 0.14%). Addition of 0.44% IL increased hemolysis to 66.5 +/- 3.4%, whereas further addition of vitamin E or C significantly inhibited hemolysis to 16.4 +/- 8.1 and 38.9 +/- 7.1%, respectively (p less than 0.0001). IL was administered i.v. to eight preterm infants. It increased 3- to 28-fold (p less than 0.001) the amount of pentane in expired breath. Partly, this increase was due to pentane dissolved in IL as a result of lipid peroxidation during storage. After discontinuing IL infusion, the elimination of pentane was nonexponential, consisting of a rapid and a slow component. According to our results, IL undergoes peroxidation causing free-radical-dependent damage to human cells. We propose that the adverse effects of parenteral IL are partially caused by free oxygen radicals generated by lipid peroxidation.

The concentration of plasma atrial natriuretic factor (ANF) and the mechanism for its secretion were investigated in 17 preterm infants with respiratory distress. Their mean gestational age was 29 wk and wt 1250 g. The infants were followed during the first week of life by sequential Doppler ultrasound studies. Ductal openness versus closure and amount of ductal flow were correlated with plasma ANF concentrations. In a subset of 10 infants, sequential Doppler color flow mapping was used to quantify the ductal flow. During the first 72 h, plasma ANF was high, 361 pg/mL; it decreased to 96 pg/mL by the end of the 1st wk. The ANF level was significantly higher when the ductus was open than closed (393 versus 123 pg/mL, p less than 0.05). In patients with open ductus and bidirectional foramen ovale shunting (n = 3) ANF was 567 pg/mL and in those with left-to-right shunt 355 pg/mL (n 15, NS). The left atrial size, i.e. the left atrial to aortic root ratio, correlated with the amount of ductal shunting (r = 0.63, p less than 0.01) and with ANF concentration (r = 0.46, p less than 0.02). The correlation of ANF values and the magnitude of left-to-right ductal shunting assessed by color flow mapping was highly significant (r = 0.66, p less than 0.001). In these patients, the elevation of ANF is reflective of ductal flow.