Validation of disease-specific biomarkers for the early detection of bronchopulmonary dysplasia

OBJECTIVE: To demonstrate and validate the improvement of current risk stratification for bronchopulmonary dysplasia (BPD) early after birth by plasma protein markers (sialic acid-binding lg-like lectin 14 (SIGLEC-14), basal cell adhesion molecule (BCAM), angiopoietin-like 3 protein (ANGPTL-3)) in extremely premature infants.METHODS AND RESULTS: Proteome screening in first-week-of-life plasma samples of n- 52 preterm infants <32 weeks gestational age (GA) on two proteomic platforms (SomaLogic (R), Olink-Proteomics (R)) confirmed three biomarkers with significant predictive power: BCAM, SIGLEC-14, and ANGPTL-3. We demonstrate high sensitivity (0.92) and specificity (0.86) under consideration of GA, show the proteins' critical contribution to the predictive power of known clinical risk factors, e.g., birth weight and GA, and predicted the duration of mechanical ventilation, oxygen supplementation, as well as neonatal intensive care stay. We confirmed significant predictive power for BPD cases when switching to a clinically applicable method (enzyme-linked immunosorbent assay) in an independent sample set (n = 25, p < 0.001) and demonstrated disease specificity in different cohorts of neonatal and adult lung disease.CONCLUSION: While successfully addressing typical challenges of clinical biomarker studies, we demonstrated the potential of BCAM, SIGLEC-14, and ANGPTL-3 to inform future clinical decision making in the preterm infant at risk for BPD.Analytical BioScience

Phosphorylation and Transport in the Na-K-2Cl Cotransporters, NKCC1 and NKCC2A, Compared in HEK-293 Cells

Na-K-2Cl cotransporters help determine cell composition and volume. NKCC1 is widely distributed whilst NKCC2 is only found in the kidney where it plays a vital role reabsorbing 20% of filtered NaCl. NKCC2 regulation is poorly understood because of its restricted distribution and difficulties with its expression in mammalian cell cultures. Here we compare phosphorylation of the N-termini of the cotransporters, measured with phospho-specific antibodies, with bumetanide-sensitive transport of K+ (86Rb+) (activity) in HEK-293 cells stably expressing fNKCC1 or fNKCC2A which were cloned from ferret kidney. Activities of transfected transporters were distinguished from those of endogenous ones by working at 37°C. fNKCC1 and fNKCC2A activities were highest after pre-incubation of cells in hypotonic low-[Cl−] media to reduce cell [Cl−] and volume during flux measurement. Phosphorylation of both transporters more than doubled. Pre-incubation with ouabain also strongly stimulated fNKCC1 and fNKCC2A and substantially increased phosphorylation, whereas pre-incubation in Na+-free media maximally stimulated fNKCC1 and doubled its phosphorylation, but inhibited fNKCC2A, with a small increase in its phosphorylation. Kinase inhibitors halved phosphorylation and activity of both transporters whereas inhibition of phosphatases with calyculin A strongly increased phosphorylation of both transporters but only slightly stimulated fNKCC1 and inhibited fNCCC2A. Thus kinase inhibition reduced phosphorylation and transport, and transport stimulation was only seen when phosphorylation increased, but transport did not always increase with phosphorylation. This suggests phosphorylation of the N-termini determines the transporters' potential capacity to move ions, but final activity also depends on other factors. Transport cannot be reliably inferred solely using phospho-specific antibodies on whole-cell lysates

Physical stimulation of newborn infants in the delivery room

Objective Neonatal resuscitation guidelines recommend that newborn infants are stimulated to assist with the establishment of regular respirations. The mode, site of application and frequency of stimulations are not stipulated in these guidelines. The effectiveness of stimulation in improving neonatal transition outcomes is poorly described. Methods We conducted a retrospective review of video recordings of neonatal resuscitation at a tertiary perinatal centre. Four different types of stimulation (drying, chest rub, back rub and foot flick) were defined a priori and the frequency and infant response were documented. Results A total of 120 video recordings were reviewed. Seventy-five (63%) infants received at least one episode of stimulation and 70 (58%) infants were stimulated within the first minute after birth. Stimulation was less commonly provided to infants = 30 weeks' gestation (1 (1-3); p<0.001). The most common response to stimulation was limb movement followed by infant cry and facial grimace. Truncal stimulation (drying, chest rub, back rub) was associated with more crying and movement than foot flicks. Conclusion Less mature infants are stimulated less frequently compared with more mature infants and many very preterm infants do not receive any stimulation. Most infants were stimulated within the first minute as recommended in resuscitation guidelines. Rubbing the trunk may be most effective but this needs to be confirmed in prospective studies