Improving handover between the transport team and neonatal intensive care unit staff in neonatal transports using the plan-do-study-act tool.

OBJECTIVES: The aim was to achieve 100% effective handover from the critical care transport team to the neonatal intensive care unit (NICU) medical team. STUDY DESIGN: All patients transferred from referring hospitals by the critical care transport team to the Level IV NICU were included. Data for each infant was collected prospectively. The percentage of transported patients for which medical team and nursing handover occurred was recorded. A quality improvement project was launched using the Plan-Do-Study-Act (PDSA) tool. We implemented several processes including call from the transport team before arrival and the completion of a transfer of care form on arrival to the NICU. The process measures and the outcome measure of completion of handover were monitored. Run charts of process measures and the outcome measure were analyzed. RESULTS: Completion of medical handover increased from 95% (baseline) to 100% after 3 PDSA cycles and this has been maintained for 18 consecutive months. CONCLUSION: Medical handover from the critical care transport team to the NICU medical staff has been achieved and sustained for all neonatal transports.

Developmental regulation of SP-A receptor in fetal rat lung.

We studied the ontogeny and developmental regulation of the recently isolated SP-A receptor in fetal and postnatal rat lung. Our results show that SP-A receptor protein levels are first detectable at 16-18 days' gestation in fetal rat lung. There is a biphasic change in its levels with an initial marked increase during late gestation, a decrease in the early postnatal period (4-7 days of age), followed by another rise in levels during the second postnatal week. The results of binding isotherms show that maximal binding of monoclonal antibody to the receptor increases with differentiation of the type II cell, indicating that the increase during fetal lung development is due in part to increased numbers of receptors per cell. Bombesin (10 nM-1 microM) enhanced SP-A receptor protein levels threefold in fetal lung explants as early as 6 hours in culture. This effect of bombesin was associated with increased proliferation of type II cells as measured by levels of proliferating cell nuclear antigen (PCNA). We conclude that the increase in SP-A receptor protein level in late gestation fetal rat lung is due to increased numbers of receptors per cell and increased numbers of type II cells. Bombesin may have an important role during lung development by paracrine mechanisms that result in proliferation of lung cells.

Effects of salmeterol on secretion of phosphatidylcholine by alveolar type II cells.

Beta-adrenergic agents enhance secretion of phosphatidylcholine (PC) by adult and fetal type II cells. We have previously shown that terbutaline stimulates secretion of PC by fetal type II cells, but the response wanes after 30 minutes. We studied the effects of salmeterol, a highly selective, long-acting beta2-adrenergic agonist that does not cause receptor desensitization, on PC secretion by adult type II alveolar cells in primary culture. Release of lactate-dehydrogenase was < 4% and did not vary with the concentration of salmeterol. Salmeterol stimulated PC secretion in a concentration-dependent manner. The maximum effective-concentration tested was 50 nM and the EC50 was 11.40 +/- 1.14 nM. Propranolol inhibited the effect of salmeterol on release of PC, confirming that the effects of salmeterol are mediated by beta-receptors. OT50, the time for onset of action, was 32.0 +/- 1.6 minutes. RT50, the time to achieve 50% recovery from maximal stimulation was, 393.0 +/- 20.2 minutes. We conclude that salmeterol stimulates PC secretion by type II cells through activation of beta-adrenergic receptors and has a longer duration of action (>6 hours) compared to other beta2-agonists. Salmeterol may be a useful drug with which to study the role of receptor desensitization in the developmental changes in PC secretion.

Neutrophil apoptosis during the development and resolution of oleic acid-induced acute lung injury in the rat.

The oleic acid (OA) model of acute lung injury in rats is characterized by a massive and rapid influx of polymorphonuclear neutrophils (PMN) within 1 h, with a peak inflammatory response at 4 h and resolution by 72 h. We hypothesized that PMN apoptosis is involved in the resolution of OA-induced acute lung injury. To test this hypothesis, healthy adult Fischer 344 rats were given 30 microl OA in 0.1% bovine serum albumin (BSA) intravenously; controls were given BSA alone and killed at 1, 4, 24, and 72 h after OA to obtain bronchoalveolar lavage fluid (BALF) and lung tissue. Cell pellets from BALF and formalin-fixed, paraffin-embedded tissue section samples were processed for terminal deoxyribonucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) to identify apoptotic cells. Propidium iodide was used to counterstain nuclei. Percentage of nuclei undergoing apoptosis was counted under a fluorescent microscope. Control rats showed only resident alveolar macrophages (AM) in the BALF with no apoptosis. At the peak of injury, 1 h and 4 h after OA injection, we observed a massive PMN response without any evidence of apoptosis. At 24 h, when the OA injury is clinically and histologically in early resolution, we observed intense apoptosis of PMN nuclei along with evidence of apoptotic bodies in the cytoplasm of AM. Some of the AM also showed apoptotic nuclei at 72 h. Similar observations were made in the lung tissue sections. The results of the TUNEL assay were confirmed by DNA ladders and electron microscopy. We conclude that apoptosis of PMN and clearance by AM is an important mechanism in resolution of OA- induced acute lung injury.

Meta-analyses of surfactant replacement therapy of infants with birth weights less than 2000 grams.

OBJECTIVES: We conducted a meta-analysis of surfactant replacement therapy to determine (1) the efficacy of surfactant therapy in the reduction of short-term morbidity and long-term outcome in terms of bronchopulmonary dysplasia (BPD) and mortality; (2) whether there are differences in efficacy between modified natural surfactant and synthetic surfactant; (3) the effectiveness of prophylactic surfactant therapy; and (4) whether there are differences in efficacy between the prophylactic approach and the rescue strategy. STUDY DESIGN: We included studies in which infants with birth weights between 500 and 1500 gm were eligible. Studies were grouped into the following categories: (1) rescue therapy with modified natural surfactant; (2) rescue therapy with synthetic surfactant; (3) prophylaxis with modified natural surfactant; (4) prophylaxis with synthetic surfactant; (5) prophylaxis versus rescue studies; (6) modified natural surfactant versus Exosurf (Burroughs-Wellcome Co., Research Triangle Park, NC) studies. The relative risk ratios, corrected for study size, were calculated for the outcome variables (pneumothorax, incidence of BPD, survival, survival without BPD, prevention of hyaline membrane disease [HMD], and intraventricular hemorrhage [IVH]). RESULTS AND CONCLUSION: Surfactant therapy is efficacious in reducing the risk for pneumothorax and increasing the chance for survival without BPD. Synthetic surfactant is not efficacious in the prevention of HMD. Modified natural surfactant is more effective in reducing the risk of pneumothorax and increasing the chance for survival without BPD than is synthetic surfactant. These data do not support the use of either synthetic or modified natural surfactant for routine prophylaxis.

Isolation and partial characterization of a receptor to surfactant protein A expressed by rat type II pneumocytes.

Surfactant protein A (SP-A), the most abundant protein component in pulmonary surfactant, has been shown to enhance surfactant phospholipid uptake by the type II alveolar epithelial cell. Recent evidence has shown that this process may be receptor-mediated. We undertook this study to isolate the putative receptor from type II cell membranes. We isolated two specific SP-A binding proteins from type II cells with apparent molecular weights (Mr) of 86 and > 200 kD under nonreducing conditions. Under reducing conditions, the higher-Mr protein was not present, but three proteins with apparent Mr of 65, 55, and 50 kD were visible, in addition to the 86-kD protein, indicating that the higher-Mr protein was composed of the smaller peptides which form disulfide bonds. The 86-kD protein is a glycoprotein with approximately 30% of its mass as carbohydrate. The 50-kD protein is also a glycoprotein (approximately 30% of its mass as carbohydrate), and SP-A binds to the protein core. Polyclonal and monoclonal antibodies to these peptides saturably bind to the surface of type II cells but not other lung cells, as shown by immunohistochemistry. SP-A competitively inhibits binding of one monoclonal antibody to type II cells, and the monoclonal antibody was able to block the effect of SP-A on phospholipid uptake by type II cells, indicating that this complex is a receptor to SP-A which is expressed on type II cells. This novel receptor is fundamental to the biology of surfactant metabolism in the lung.

Gestational age can predict the need for prophylaxis with surfactant therapy.

Controversy exists as to whether prophylactic or rescue therapy with surfactant should be used in infants born at less than 30 weeks gestation. We developed the hypothesis that gestational age can be used to predict a need for prophylactic surfactant therapy. We designed this retrospective study to determine whether there was a gestational age below which one could accurately predict the need for prophylactic surfactant therapy in almost all infants and limit unnecessary treatment of infants. We conducted a retrospective study of infants born at 23-34 weeks' gestation to determine the frequency with which surfactant therapy was used in a rescue strategy at each gestational age, and to ascertain the sensitivity, specificity, and predictive values of gestational age as a predictor of the use of surfactant therapy. There was a significant inverse correlation between gestational age and the proportion of infants treated with surfactant (r = -0.923, p < 0.001). A gestational age cut-off of 26 completed weeks' had a positive predictive value of 85% and a specificity of 96% for the need for surfactant therapy. We conclude that gestational age can be used to predict a need for surfactant therapy in premature infants. At our institution, the failure to attain 26 completed weeks' gestation will accurately predict the need for surfactant therapy and will result in unnecessary treatment of very few infants. We suggest that each institution caring for very low birth weight infants should examine its population to determine the gestational age at which they can accurately predict the need for prophylaxis with surfactant therapy.

Ontogeny of apoptosis during lung development.

Apoptosis has been shown to be involved in several processes during embryogenesis, but the ontogeny of apoptosis during lung development ahs not been studied. The goals of the current study were to determine if apoptosis occurs during lung development, and to determine the ontogeny of the changes in apoptosis that occur. We studied the ontogeny of apoptosis in vivo using lungs from 14-18-d gestation fetal rats, newborn rats, and 1-d-, 2-d-, 5-d-, and 10-d-old rat pups. Apoptosis was assessed by electron microscopy and the terminal deoxyribonucleotidyl transferase dUTP nick end-labeling assay. We compared the in vivo results with explants of 14-d gestation fetal rat lung placed in culture for 1-4 d because the biochemical development of the lung in organ culture has been shown to closely parallel the development of the lung in vivo. We found apoptosis of mesenchymal cells at the periphery of distal lung buds in early fetal lung (14-16-d gestation). Apoptosis of both mesenchyme and epithelium was present in later fetal lung (18-d gestation). There were no qualitative differences in apoptosis between in vivo fetal lung and explant cultures of fetal lung. There was a 14-fold increase in apoptosis at birth and in the first postnatal day of life (9-12% of cells) compared with fetal lung (0.6-1% of cells). This was followed by a rapid decline in the percentage of apoptotic cells to fetal levels at postnatal d 2-10. We conclude that apoptosis occurs in a spatially, temporally, and cell-specific manner during lung development. The number of cells undergoing apoptosis increases dramatically in the first day after birth.

Developmental regulation of the effects of surfactant protein A on phospholipid uptake by fetal rat type II pneumocytes.

Surfactant protein A (SP-A) enhances the uptake of phospholipid by type II cells derived from adult and late gestation fetal rat lung. The present study was performed to examine more fully the developmental biology of the effects of SP-A on phosphatidylcholine (PC) uptake, to determine the effect of SP-A on the cellular location of bound and internalized phospholipid and on the metabolism of internalized phospholipid by morphologically undifferentiated (18-day) and morphologically differentiated (19-day) fetal type II cells. SP-A enhanced uptake almost two-fold in a dose-dependent manner in 19-day fetal cells, but it had no effect on uptake by 18-day fetal cells at any concentration. Stimulation of uptake by 19-day fetal cells was saturable at concentrations above 1 microgram/ml SP-A. Maximal uptake was 1.12 nmol of PC/mg of protein, and the effective concentration that yields 50% maximal response, K phi, was 58.9 ng/ml (84.1 pM). The effect of SP-A on uptake by 19-day fetal cells was detectable as early as 1 min of exposure. Uptake correlated significantly with time both in the absence (r = 0.98, p < 0.001) and presence of 5 micrograms/ml SP-A (r = 0.979, p < 0.001). The rate of uptake in the presence of SP-A (0.019 +/- 0.002 nmol of PC/mg of protein/min) was twice the rate of uptake in controls (0.009 +/- 0.001 nmol of PC/mg of protein/min). SP-A had no effect on binding to plasma membranes and uptake of phospholipid into lamellar bodies by 18-day fetal cells. On the other hand, SP-A significantly enhanced binding of dipalmitoyl phosphatidylcholine to plasma membranes (two- to threefold) and uptake into lamellar bodies (threefold) of 19-day fetal cells. SP-A caused a significant reduction in the degradation of internalized phospholipid by differentiated fetal type II cells. Based on the lack of effect of exogenous SP-A on 18-day fetal cells, we conclude that the response to SP-A is under developmental control. SP-A enhances the initial binding to the plasma membranes of fetal type II cells and subsequent internalization into the lamellar bodies. This effect is associated with a protection of internalized phospholipid from metabolic degradation. Both of these processes are developmentally regulated during the transition from the canalicular to the saccular phase of lung development.

Hyperoxia inhibits fetal rat lung fibroblast proliferation and expression of procollagens.

The direct effects of hyperoxia on collagen production by fetal lung fibroblasts are unknown and would be important to the understanding of the molecular mechanisms involved in bronchopulmonary dysplasia in premature infants. We studied the effect of hyperoxia on 1) proliferation, 2) mRNA levels for type I and III procollagens, and 3) net collagen production in primary cultures of fetal rat lung fibroblasts. Fibroblasts from 19-day-old rat fetuses (term is 22 days) were obtained. Test plates were incubated in hyperoxia and controls in room air for varying time periods. Cell viability in both conditions was >97% as determined by trypan blue exclusion. Fibroblast proliferation in nonconfluent cultures was found to be significantly reduced with exposure to hyperoxia (P < 0.001). Steady-state levels of type I and III procollagen mRNAs, analyzed on Northern blots hybridized to [32P]cDNA probes, were significantly decreased in hyperoxia (P < 0.01). This effect was noted as early as 4 h of exposure to hyperoxia and persisted for 5 days. There was a significant inverse correlation between duration of exposure to O2 and steady-state levels of mRNA for alpha1(I)-procollagen (r = -0.904) and alpha1(III)-procollagen (r = -0.971). There were no significant changes in steady-state levels of beta-actin mRNA. We also found a significant decrease in collagen synthesis in hyperoxia-exposed fibroblasts (P < 0.05). We conclude that hyperoxia directly effects a reduction in fetal lung fibroblast proliferation and net collagen production at a pretranslational level.

Actin depolymerization is developmentally regulated in rat type II cells exposed to terbutaline.

The type II alveolar epithelial cell synthesizes and secretes pulmonary surfactant. Terbutaline enhances phospholipid release from adult and fetal type II cells. Our hypothesis is that the actin network of microfilaments regulates the secretory activity of the type II cell. To examine the developmental regulation of the changes in actin subfractions associated with secretory activity, cultures of type II cells derived from adult and 19-d fetal rat lung were incubated with or without 10 microM terbutaline for 1, 30, and 60 min. Dose-response effects of terbutaline were examined in adult type II cells. Effects of phorbol ester were also examined Globular (G-actin) and filamentous (F-actin) fractions were extracted from the cells and analyzed separately. Specified cellular equivalent volumes of each subfraction were analyzed by Western blotting, visualized by a color reaction, and quantified by densitometry. There was a decrease in the cytoskeletal F-actin pool along with an increase in the G-actin fraction within I min in adult type II cells exposed to terbutaline, indicating that depolymerization of F-actin occurs. Values returned to control levels by 60 min. In contrast, the decrease in F-actin, with a concomitant increase in G-actin, was maximal at 60 min in fetal cells exposed to terbutaline. There was a dose-dependent increase in actin depolymerization with maximal effects at 10 microM terbutaline. Phorbol ester also caused an increase in actin depolymerization. Depolymerization of the actin microfilament network may regulate transport and exocytosis of lamellar bodies in type II cells. We speculate that there is an early secretory mechanism that involves depolymerization of actin microfilaments and a late, actin-independent secretory mechanism present in adult type II cells. The timing of the response of the actin-dependent pathway is developmentally regulated. This may explain the developmental differences in the secretion of surfactant that we have previously shown.

Developmental regulation of phospholipid secretion by fetal type II pneumocytes.

Surfactant sufficiency is dependent upon adequate synthesis and secretion of surfactant by the type II alveolar epithelium. Our laboratory has previously shown that basal secretion of surfactant phospholipid by differentiated fetal type II cells is lower than the basal secretion by adult cells. The purposes of this study were to determine if undifferentiated fetal type II cells can secrete phosphatidylcholine, to determine if terbutaline, a beta-adrenergic agonist, stimulates secretion of surfactant phospholipids by undifferentiated fetal cells and to examine the effects of differentiation on secretion of surfactant phospholipids by fetal cells. Constitutive (basal) secretion of phosphatidylcholine increased linearly as a function of time in both undifferentiated and differentiated cells, but the rate of secretion was greater in differentiated cells than the rate of secretion in undifferentiated cells. Terbutaline caused a concentration-dependent increase in secretion in both undifferentiated and differentiated cells. Maximal effective concentration and EC50 were similar for undifferentiated (10(-6) M, 0.2 microM) and differentiated (10(-5) M, 0.3 microM) cells. The relative stimulation of secretion above control values was greater for undifferentiated cells. The kinetics of terbutaline stimulation varied significantly with cellular differentiation. Terbutaline resulted in 230% stimulation of secretion in undifferentiated cells at 30 min followed by a decline in the response to terbutaline at 60 to 120 min. In contrast, terbutaline stimulated secretion by differentiated cells showed a sustained linear increase from 0 to 120 min. This regulation of stimulated secretion is not present in undifferentiated cells. We conclude that undifferentiated type II cells are capable of the secretion of phosphatidylcholine and that terbutaline stimulates secretion by undifferentiated cells. Furthermore, basal secretion increases as a function of differentiation of type II cells and the regulation of stimulated secretion seen in differentiated cells is not developed in undifferentiated cells. The developmental regulation of the secretion of surfactant is complex and probably involves both excitatory as well as inhibitory mechanisms which develop at different stages of differentiation of the type II cell.

Characterization of Ca(2+)-release channels in fetal and adult rat hearts.

The goal of this study was to characterize the Ca(2+)-release channel in whole homogenates of left (LV) and right ventricles (RV) of fetal (22 days in gestation) and adult Sprague-Dawley rat hearts using [3H]ryanodine binding and 45Ca2+ fluxes. Although many features of the Ca(2+)-release channels were similar in fetal and adult hearts, biochemical assays revealed quantitative differences. Similar properties include 1) Ca(2+)-sensitive cooperative ryanodine binding to Ca(2+)-release channel, measured as Ca2+ concentration for half-maximal activation (fetal LV: 0.13 +/- 0.02 microM; adults LV: 0.15 +/- 0.02 microM) and Hill coefficient (fetal LV: 2.5 +/- 0.9; adult LV: 2.7 +/- 0.5), and 2) caffeine-sensitive ryanodine binding, measured as the percent increase in ryanodine binding induced by caffeine (fetal LV: 148.8 +/- 16.9% vs. adult LV: 171.4 +/- 34.9%). The distinguishing property was the lower Ca(2+)-release channel density in the fetal heart (LV: 0.22 +/- 0.03 pmol/mg protein) compared with adult heart (LV: 0.59 +/- 0.04 pmol/mg protein; P < 0.05), as determined by [3H]ryanodine binding. The lower density of Ca(2+)-release channel is supported by the finding that there is very low ryanodine-sensitive oxalate-supported 45Ca2+ uptake in the fetal heart. The tested characteristics of the Ca(2+)-release channel were similar between LV and RV in both fetal and adult rat hearts. Ou results indicate that expression of Ca2+-release channels in sarcoplasmic reticulum increases during postnatal growth in the rat heart. This is consistent with previous physiological reports that Ca2+ available for excitation-contraction coupling in the fetal heart is derived mainly from transsarcolemmal Ca2+ influx.

Developmental regulation of re-uptake of phosphatidylcholine by type II alveolar epithelium.

Type II alveolar epithelia produce, store and secrete pulmonary surfactant, a phospholipid and protein mixture which stabilizes alveoli at low lung volumes and, thereby, prevents alveolar collapse. We determined the developmental changes in the uptake, metabolism and reutilization of surfactant-related phospholipid in primary cultures of type II cells derived from fetal rat lung. Primary cultures of fetal and neonatal type II cells were incubated in media containing labelled liposomes. After the incubation phospholipids were extracted from the cells and uptake of label was analyzed. Re-uptake of radiolabelled dipalmitoyl phosphatidylcholine (DPPC) was concentration-dependent in undifferentiated fetal cells, differentiated fetal cells and neonatal cells. Re-uptake of DPPC by undifferentiated fetal cells was lower than re-uptake by both differentiated fetal and neonatal cells at 15 and 75 microM PC. Binding of DPPC to the cell surface involved a protein interaction, since trypsin was able to dissociate this trypsin-releasable fraction from internalized label. Undifferentiated fetal, differentiated fetal and neonatal cells all exhibited approx. 50% metabolic degradation of internalized phospholipid. Degraded lipids were reutilized in the synthesis of phosphatidylglycerol, but neonatal cells resynthesized twice as much phosphatidylglycerol as did undifferentiated fetal cells. These are the first studies which show that morphologically undifferentiated fetal type II cells are capable of the uptake of surfactant phospholipid as well as the degradation and reutilization of internalized phospholipid. Re-uptake, degradation and reutilization of internalized phospholipid appear to be under developmental control.

Magnetic resonance imaging in full-term infants with repetitive focal seizures.

We report two full-term infants who developed repetitive focal seizures within the first 48 hours of life. Neither infant had predisposing factors and there were no abnormalities on a computed tomography (CT) scan performed on day 2 of life. Magnetic resonance imaging (MRI) performed during the second week of life showed a focal hemorrhagic infarction in both patients. We conclude that either an MRI or a contrast-enhanced CT scan should be obtained within 1 week in patients in whom the initial imaging technique failed to reveal a focal lesion, at which time a cerebral infarction can be diagnosed with greater sensitivity.

Long-bone radiographic abnormalities as a sign of active congenital syphilis in asymptomatic newborns.

Metaphyseal abnormalities are present in greater than 90% of infants with symptomatic congenital syphilis. The incidence of these lesions in asymptomatic newborns in the present epidemic is not known. To determine the incidence of bone lesions at birth in asymptomatic congenital syphilis, long-bone films were obtained for all babies born during a 9-month period with a positive perinatal serology. Of 2544 newborns, 61 had a positive maternal serology and 40 also had a positive cord serology. Two symptomatic babies had abnormal radiographs and 12 of 59 asymptomatic newborns had metaphyseal changes consistent with congenital syphilis. It is concluded that long-bone radiographs are abnormal in approximately 20% of asymptomatic newborns with positive perinatal treponemal serology. With the increasing incidence of congenital syphilis, radiologic studies should be included in the assessment of all newborns with a positive serology. Indeed, those patients with any sign of active disease should be carefully followed because even treated infants remain at some risk for developing the late sequelae of congenital syphilis.

Comparison of the Maclura pomifera lectin-binding glycoprotein in late fetal and adult rat lung.

The lectin, Maclura pomifera agglutinin (MPA), binds to alpha-galactose residues of glycoproteins on the apical surface of type II alveolar cells. It has recently been shown to bind to macrophages. We isolated the cell surface glycoprotein, which binds the MPA lectin, from fetal and adult rat whole lung to determine if changes in this glycoprotein occur during development from fetal to adult life. The glycoprotein was purified from whole lung cell membranes by lectin affinity chromatography that resulted in 10(5)-fold enrichment. The MPA binding glycoproteins from both fetal and adult lung had the same apparent molecular weight of 170 kD as determined by sodium dodecylsulfate-polyacrylamide gel electrophoresis. Amino acid analysis revealed similar composition of the fetal and adult proteins. Two-dimensional peptide maps of the 170 kD proteins isolated from fetal and adult lung were also similar. These data indicate that the glycoprotein that binds MPA to lung cell membranes does not change during this stage of development. Our method for the isolation of this glycoprotein can be used for the generation of antibodies or other molecular probes for further study of this protein.