Implementing a successful targeted neonatal echocardiography service and a training program: The ten stages of change.

Implementing any new service or program in the health care system is not always straightforward; a multi-stage implementation process is required most of the time. With the advancements in neonatal care and increased survival rates, there has been an increased need for ongoing assessment of hemodynamic stability. At the Children's Hospital of Eastern Ontario and the Ottawa Hospital Neonatal Intensive Care Units (NICUs), University of Ottawa, Canada, Targeted Neonatal Echocardiography service (TnEcho) was successfully established and has led to improvement in the hemodynamic evaluation and decision making in neonatal intensive care. In this article, we describe our experience establishing this program and the process of ensuring its success. This review article highlights the ten steps taken by multiple stakeholders to achieve this goal; this may help other centres implement a similar program.

Allergenicity and immunogenicity of the major mugwort pollen allergen Art v 1 chemically modified by acetylation.

BACKGROUND: Treating allergies with modified allergens is an approach to make the treatment safer and more efficient. Art v 1 is the most prominent allergen of mugwort pollen and a significant cause of hayfever around Europe. The aim of this study was to reduce the allergenicity of Art v 1 by acetylation, and to investigate the capacity of the modified protein to generate blocking antibodies. METHODS: The reduction of allergenicity of Art v 1 following acetylation was monitored by immunoblot, ELISA inhibition using a pool of sera from mugwort pollen allergic patients, basophil activation assay and by skin prick testing of mugwort-allergic patients. Rabbits were immunized against Art v 1 and acetylated Art v 1 (acArt v 1) and the rabbit antisera were tested for their capacity to block human IgE binding in ELISA. Human T cell proliferation against Art v 1 and acArt v 1 was examined in peripheral blood mononuclear cells (PBMCs) of mugwort pollen allergic patients and cytokine release in PBMC cultures was monitored. RESULTS: Acetylation of Art v 1 gave a derivative of reduced allergenicity in the in vitro and ex vivo tests applied. The skin test reactivity to acArt v 1 was significantly reduced in 19 patients when compared with the reactivity to Art v 1. Rabbit antibodies to acArt v 1 and Art v 1 showed similar capacity to block human IgE binding to Art v 1 in inhibition ELISA. Both proteins were able to induce proliferation of PBMCs and CD3/CD4(+) cells of mugwort-allergic patients. Release of IL-5 was significantly reduced in cultures stimulated with acArt v 1. CONCLUSIONS: Art v 1 modified by acetylation had a significantly reduced allergenicity in vitro and in vivo, while its immunogenicity was retained. Modification of allergens by acetylation could be a new strategy for allergen-specific immunotherapy.

The identification of a low molecular mass bacteriocin, rhamnosin A, produced by Lactobacillus rhamnosus strain 68.

AIMS: This study focuses on the isolation and characterization of a peptide with bacteriocin-like properties isolated from Lactobacillus rhamnosus strain 68, previously identified by 16S rRNA gene sequencing and originating from human gastrointestinal flora. METHODS AND RESULTS: The peptide was isolated from a supernatant of bacteria maintained under restrictive conditions by a combination of ethanol precipitation and reversed-phase chromatography. The molecular mass of the peptide as assessed by mass spectrometry was 6433.8 Da. An isoelectric point of 9.8 was determined by 2D-PAGE. The peptide designated rhamnosin A inhibited Micrococcus lysodeikticus ATCC 4698 but did not inhibit Lactobacillus plantarum 8014 or Lact. plantarum 39268. Inhibitory activity against M. lysodeikticus at concentrations used in this study was shown to be bacteriostatic rather than bacteriolytic or bactericidal. Rhamnosin A retained biological activity after heat treatment (95 degrees C, 30 min) but was sensitive to proteolytic activity of pepsin and trypsin. CONCLUSIONS: The N-terminal sequence of rhamnosin A, as determined by Edman degradation and in more detail by blast analysis, did not show identity with any currently available Lact. rhamnosus HN001-translated protein sequences, nor any significant similarity with other sequences in the nonredundant protein sequence database. Being a small, heat-stable, nonlanthionine-containing peptide, rhamnosin A should be categorized as a class II bacteriocin. SIGNIFICANCE AND IMPACT OF THE STUDY: This study describes a partial bacteriocin sequence isolated from Lact. rhamnosus 68 and broadens our understanding of bacteriocins.

A bronchial epithelium-derived factor reduces pulmonary vascular tone in the newborn rat.

The factors accounting for the maintenance of a low pulmonary vascular resistance postnatally are not completely understood. The aim of this study was to test the hypothesis that bronchial epithelium produces a factor capable of relaxing adjacent pulmonary arterial smooth muscle. We studied fourth-generation intralobar pulmonary arteries and bronchi of 4- to 8-day-old rats. Arteries were mounted on a wire myograph, alone or with the adjacent bronchus. The presence of the attached bronchus significantly reduced pulmonary artery force generation induced by the thromboxane analog (U-46619) or KCl whether the endothelium was present or absent (P < 0.01). The converse was not true in that bronchial force generation was not affected when studied with the adjacent pulmonary artery. Mechanical removal of the bronchial epithelium or addition of the nitric oxide (NO) synthase (NOS) nonspecific (N(G)-monomethyl-l-arginine) or the specific neuronal NOS (7-nitroindazole) inhibitors increased arterial force generation to levels comparable to the isolated artery preparation. Wortmannin, a phosphatidylinositol 3-kinase inhibitor, significantly decreased (P < 0.01) NO release of pulmonary arteries only when the adjacent bronchus was present. We conclude that bronchial epithelium in the newborn rat produces a factor capable of lowering pulmonary vascular muscle tone. This relaxant effect can be suppressed by NOS and phosphatidylinositol 3-kinase kinase inhibition, suggesting an action via NOS phosphorylation and NO release. We speculate that such a mechanism may be operative in vivo and plays an important role in control of pulmonary vascular resistance in the early postnatal period.

Chronic O2 exposure enhances vascular and airway smooth muscle contraction in the newborn but not adult rat.

Neonatal rats exposed to 60% O(2) for 14 days develop lung changes compatible with human bronchopulmonary dysplasia and pulmonary hypertension. Our aim was to evaluate and compare the newborn and adult rat pulmonary vascular and airway smooth muscle force generation and relaxation potential after exposure to 60% O(2) for 14 days. Vascular and airway intrapulmonary rings 100 microm in diameter were mounted on a myograph and bathed in Krebs-Henseleit solution bubbled with air- 6% CO(2) at 37 degrees C. Significant age-dependent changes in intrapulmonary arteries and their neighboring airway muscle properties were observed. Whereas hyperoxia enhanced force in neonatal vascular and airway muscle, the opposite was seen in adult samples. No changes in endothelium-dependent vascular relaxation were observed at either age, but the dose response to an endothelium-independent NO donor was altered. In the newborn experimental animals, the relaxation was reduced, whereas, in their adult counterparts, it was enhanced. After O(2) exposure, the bronchial muscle relaxation response to epithelium-dependent and -independent stimulation was not altered in either age group, whereas the epithelium-dependent response was decreased only in the adult. The antioxidant Trolox, or an endothelin-A and -B receptor antagonist, reversed the vascular and airway muscle's hyperoxia-induced changes. We conclude that chronic O(2) exposure in the newborn rat results in enhanced lung vascular and airway muscle contraction potential via a mechanism involving reactive oxygen species and the endothelin pathway. The present findings also suggest that the newborn is more susceptible to airway hyperresponsiveness after chronic O(2) exposure.

Chronic O2 exposure in the newborn rat results in decreased pulmonary arterial nitric oxide release and altered smooth muscle response to isoprostane.

Chronic oxygen exposure in the newborn rat results in lung isoprostane formation, which may contribute to the pulmonary hypertension evident in this animal model. The purpose of this study was to investigate the pulmonary arterial smooth muscle responses to 8-iso-prostaglandin F(2alpha) (8-iso-PGF(2a)) in newborn rats exposed to 60% O2 for 14 days. Because, in the adult rat, 8-iso-PGF(2alpha) may have a relaxant effect, mediated by nitric oxide (NO), we also sought to evaluate the pulmonary arterial NO synthase (NOS) protein content and NO release in the newborn exposed to chronic hyperoxia. Compared with air-exposed control animals, 8-iso-PGF(2a) induced a significantly greater force (P < 0.01) and reduced (P < 0.01) relaxation of precontracted pulmonary arteries in the 60% O2-treated animals. These changes were reproduced in control pulmonary arteries by NOS blockade by using NG-nitro-L-arginine methyl ester. Pulmonary arterial endothelial NOS was unaltered, but the inducible NOS protein content was significantly decreased (P < 0.01) in the experimental group. Pulmonary (P < 0.05) and aortic (P < 0.01) tissue ex vivo NO accumulation was significantly reduced in the 60% O2-treated animals. We speculate that impaired pulmonary vascular tissue NO metabolism after chronic O2 exposure potentiates 8-iso-PGF(2alpha)-induced vasoconstriction in the newborn rat, thus contributing to pulmonary hypertension.

Effect of 8-isoprostaglandin F2alpha on the newborn rat pulmonary arterial muscle and endothelium.

8-Isoprostaglandin F2alpha (8-iso-PGF2alpha) is a bioactive lipid peroxidation product that is a vasoconstrictor at high concentrations. Paradoxically, at lower, and possibly physiological, concentrations, it is a pulmonary vascular muscle's relaxant. Its effects on newborn pulmonary vasculature are unknown. We hypothesized that the pulmonary arterial 8-iso-PGF2alpha responses may be developmentally regulated. Therefore, the purpose of this study was to evaluate and compare 8-iso-PGF2alpha effects between 1- and 2-wk-old newborn and adult rat isolated intrapulmonary arteries (100 microm) mounted on a myograph. Force after 8-iso-PGF2alpha stimulation was greatest in the adult (P < 0.01). In newborns, force was significantly increased by the nitric oxide (NO) synthase inhibitor NG-nitro-l-arginine methyl ester (l-NAME) (P < 0.01) and was suppressed by blockade of the thromboxane (Tx) A2 receptor. Whereas 8-iso-PGF2alpha induced a significant dose-dependent relaxation of adult precontracted vessels in the presence of a TxA2 mimetic (U-46619; 1 microM), contraction was observed in the 1-wk-old rat. This 8-iso-PGF2alpha-induced contraction was abolished by endothelium removal and l-NAME and was attenuated by the cyclooxygenase inhibitor ibuprofen. In the presence of a TxA2/prostaglandin H2 receptor blocker, 8-iso-PGF2alpha induced NO-mediated relaxation, the magnitude of which was greater in the newborn, compared with the adult (P < 0.01). When exposed to 8-iso-PGF2alpha in vitro, only the newborn lung secreted TxB2. We conclude that, in contrast to its relaxant effect in the adult, 8-iso-PGF2alpha induces contraction of the pulmonary arteries in the early postnatal period, which is likely to be mediated by endothelium-derived TxA2. This phenomenon may contribute to the maintenance of a higher pulmonary vascular resistance in the early postnatal period.

Passage of delta sleep-inducing peptide (DSIP) across the blood-cerebrospinal fluid barrier.

Unidirectional flux of 125I-labeled DSIP at the blood-tissue interface of the blood-cerebrospinal fluid (CSF) barrier was studied in the perfused in situ choroid plexuses of the lateral ventricles of the sheep. Arterio-venous loss of 125I-radioactivity suggested a low-to-moderate permeability of the choroid epithelium to the intact peptide from the blood side. A saturable mechanism with Michaelis-Menten type kinetics with high affinity and very low capacity (approximate values: Kt = 5.0 +/- 0.4 nM; Vmax = 272 +/- 10 fmol.min-1) was demonstrated at the blood-tissue interface of the choroid plexus. The clearance of DSIP from the ventricles during ventriculo-cisternal perfusion in the rabbit indicated no significant flux of the intact peptide out of the CSF. The results suggest that DSIP crosses the blood-CSF barrier, while the system lacks the specific mechanisms for removal from the CSF found with most, if not all, amino acids and several peptides.

Saturable mechanism for delta sleep-inducing peptide (DSIP) at the blood-brain barrier of the vascularly perfused guinea pig brain.

Cellular uptake of [125I] labelled DSIP at the luminal interface of the blood-brain barrier (BBB) was studied in the ipsilateral perfused in situ guinea pig forebrain. Regional unidirectional transfer constants (Kin) calculated from the multiple-time brain uptake analysis were 0.93, 1.33 and 1.66 microliter.min-1 g-1 for the parietal cortex, caudate nucleus and hippocampus, respectively. In the presence of 7 microM unlabelled DSIP the brain uptake of [125I]-DSIP (0.3 nM) was inhibited, the values of Kin being reduced to 0.23-0.38 microliter.min-1 g-1, values that were comparable with the Kin for mannitol. The rapidly equilibrating space of brain, measured from the intercept of the line describing brain uptake versus time on the brain uptake ordinate, Vi, was greater for [125I]-DSIP than for mannitol; in the presence of unlabelled DSIP this was reduced to that of mannitol, and it was suggested that the larger volume for [125I]-DSIP represented binding at specific sites on the brain capillary membrane. L-tryptophan, the N-terminal residue of DSIP, in concentrations of 7 microM and 1 mM, inhibited Kin without affecting Vi. A moderate inhibition of Kin was obtained by vasopressin ([Arg8]-VP), but only at a concentration as high as 0.2 mM. The results suggest the presence of a high affinity saturable mechanism for transport of DSIP across the blood-brain barrier, with subsequent uptake at brain sites that are highly sensitive to L-tryptophan, and may be modulated by [Arg8]-VP.

Oxidation products of hyperforin from Hypericum perforatum.

The isolation of two oxidation products of hyperforin from the aerial parts of Hypericum perforatum and their structure determination by means of 2D NMR methods is reported. The products had the same 1-(2-methyl-1-oxopropyl)-2,12-dioxo-3,10 beta-bis(3-methyl-2-butenyl)-11 beta-methyl-11 alpha-(4-methyl-3-pentenyl)-5-oxatricyclo[6.3.1.0(4,8)]-3-dodec ene skeleton. In addition, one of them, with the same number of carbons as hyperforin (C35H52O5), contained a 1-methyl-l-hydroxyethyl group in the 6 beta-position, whereas the other compound (a hemiacetal, C32H46O5), presumably a degradation product of hyperforin, exhibited a 6-hydroxy function. The latter was an inseparable mixture of 6 alpha- and 6 beta-hydroxy epimers undergoing (according to phase sensitive NOESY) mutual interconversion.

Microbiologic transformation of progesterone by Curvularia clavata Jain.

Progesterone was transformed microbiologically by the fungal strain Curvularia clavata Jain. Progesterone (I) was added as substrate when the microorganism reached its exponential growth phase. Three substances were isolated after the fermentation: a non-steroidal substance, radicinin (II), which has been established to be a metabolic product of the fungus and acts as a phytotoxin, and two steroidal substances which resulted from fungal enzymatic action on the progesterone molecule. The structure of each microbial metabolite was elucidated by 1H-nuclear magnetic resonance, mass spectrometry, and infrared and UV analyses, and the yields were determined by high-pressure liquid chromatography. The progesterone metabolites were characterized as 7 alpha,14 alpha-dihydroxypregn-4-ene-3,20-dione (III) and 11 beta, 14 alpha-dihydroxypregn-4-ene-3,20-dione (IV). Evidence for the structure of these steroidal products came from derivatives resulting from acetylation and dehydration.

Randomised, controlled trial of nasal continuous positive airway pressure in the extubation of infants weighing 600 to 1250 g.

AIM: To determine whether extubation to nasal continuous airway pressure (NCPAP) results in a greater proportion of infants remaining free of additional ventilatory support for one week after extubation compared with those extubated directly to headbox oxygen. METHODS: A randomised, controlled, clinical trial was conducted at the neonatal intensive care unit of the Royal Women's Hospital, Melbourne, of infants with birthweights between 600 and 1250 g, ventilated via an endotracheal tube for more than 12 hours, requiring less than 50% oxygen, a ventilator rate < or = 20/minute, considered by the clinical management team to be ready for extubation. Infants were randomly allocated either to NCPAP or to oxygen administered via a headbox. Success was defined by no requirement for additional ventilatory support over the week following extubation. Failure criteria were (i) apnoea; (ii) absolute increase in oxygen requirement greater than 15% above than required before extubation; or (iii) respiratory acidosis (pH < 7.25 with pCO2 > 6.67 kPa). RESULTS: Thirty one of 47 (66%) infants were successfully extubated to NCPAP compared with 18 of 45 (40%) for headbox oxygen. The increase in failure rate in the headbox group was due primarily to increased oxygen requirements in this group. Of the 27 who failed headbox oxygen, 26 were given a trial of NCPAP and 13 did not require endotracheal reintubation. There was no significant difference between the groups in the total number of days of assisted ventilation or the duration of inpatient stay. CONCLUSIONS: NCPAP applied prophylactically after endotracheal extubation reduces the incidence of adverse clinical events that lead to failure of extubation in the seven days after extubation. This reduction is clinically important. The benefits of NCPAP do not seem to be associated with an increased incidence of unwanted side effects.

Isolation and partial characterization of Fes p 4 allergen.

More than 75% of grass pollen-allergic patients produce specific IgE antibodies against group-4 allergens. Purification and characterization of different grass group-4 allergens should help to further understand their allergenicity. In this study, an attempt was made to isolate and characterize Fes p 4 allergen by several biochemical and immunochemical methods. Fes p 4 was purified by a combination of chromatographic techniques (gel permeation and ion exchange chromatography). Isolated protein revealed four main spots at a molecular weight of 60 kDa and a pI ranging from 8.7 to 9.1. Eight sera were selected from patients with positive result of skin prick test to the mixture of grass pollen extracts. ELISA inhibition technique was used to study Fes p 4-specific IgE in the patients' sera. ELISA to Festuca pratensis was inhibited up to 80% by F. pratensis pollen extract and up to 48% by Fes p 4. 2D-PAGE-immunoblot was used to identify allergenic and antigenic components of Fes p 4 with patients' IgE and monoclonal antibodies (MABs). Three components of purified protein expressed IgE binding ability. Two MABs which recognized unrelated regions on Phl p 4, bound three components of Fes p 4. The role of the carbohydrate moiety in allergenicity was examined with individual patient sera by using periodate-treated Fes p 4. Six out of eight patients reduced IgE binding to periodate-treated allergen. Isolated Fes R 4 glycoprotein consisted of four components, three of which were allergenic, and share common epitopes specific for grass group-4 homologs. The results of periodate oxidation of Fes p 4 suggest that the carbohydrate moiety is involved in IgE binding.

IgE cross-reactivity between meadow fescue pollen and kiwi fruit in patients' sera with sensitivity to both extracts.

BACKGROUND: The presence of IgE reactivity to kiwi fruit and grass pollen allergens which could be caused by cross-reactivity has been detected in many patients with allergy. Proper identification of allergens as well as cross-reactive components is essential for understanding fruit- and pollen-associated hypersensitivity. METHODS: Using the sera from the polysensitized patients with specific IgE to grass pollen and kiwi fruit we tested reactivity to both allergen sources. IgE reactivity was exhibited in 8 serum samples by immunoblot. A serum pool formed by 8 individual sera was used for the investigation of IgE crossreactivity. SDS-PAGE immunoblot-inhibition assay was performed by preincubation of the sera with meadow fescue pollen, kiwi fruit extract, and isolated 24 kDa kiwi protein. To determine the allergens of kiwi fruit extract, we performed 2D PAGE immunoblot. In order to detect the crossreactive components between two allergen sources, a specific IgE for the 24 kDa kiwi allergen was purified. RESULTS: SDS-PAGE immunoblot meadow fescue pollen showed allergens ranging from 94 to 16 kDa, and kiwi fruit had 12 allergens ranging from 94 to 17 kDa. 2D-PAGE analysis revealed at least 15 spots in the kiwi extract and about 10 allergens. The most prominent allergen in 2D PAGE immunoblot was protein with 24 kDa and pI 9.4-9.5. Using an affinity-purified specific IgE we found that the 24 kDa kiwi allergen shared IgE-reactive epitopes with the meadow fescue group 4 and allergen about 36 kDa. Crossreactivity between isolated 24 kDa kiwi allergen and Fes p 4 was confirmed by anti-grass group 4 moab 2D8. CONCLUSION: Our findings showed that fescue meadow pollen cross-sensitize to kiwi fruits. A 24 kDa kiwi glycoprotein represent potential major allergen, which share common epitopes with Fes p 4 and 36 kDa meadow fescue allergen.

Effect of valency on binding properties of the antihuman IgM monoclonal antibody 202.

A murine monoclonal IgG2a antibody, 202, specific for human IgM, was produced and immunochemically characterized. Binding features of MAb 202, epitope localization, and its accessibility at the quaternary structure of polymeric IgM were investigated. Direct and competitive ELISA with fragments of IgM molecule demonstrated that the epitope recognized by MAb 202 lies on the Fc3 portion of IgM. Sandwich ELISA with MAb 202, which could be used simultaneously to capture and to detect bound IgM, indicated that more than one 202 epitope is present on the IgM molecule. MAb 202 did not precipitate IgM in solution, whereas good precipitation lines were obtained in agarose gel. Binding of MAb 202 to the J chain, C-terminal tailpiece and C mu 2 peptide, which remain attached to the C mu 3 domain of the Fc5 fragment, was excluded by a number of experimental results and structural reasons. Therefore a potential candidate for epitope 202 expression was the C mu 3 domain. MAb 202 did not react with isolated mu chain, which is expected since epitope 202 is of a conformational type. Furthermore, the reaction with monomeric IgM was almost undetectable as was demonstrated by a number of methods (ELISA, immunofluorescence, Western blotting). Since monovalent Fab portions of MAb 202 weakly reacted with polymeric IgM, we concluded that intrinsic affinity of their interaction is low but greatly enhanced by bivalent binding. Antipolymeric IgM binding specificity of MAb 202 was demonstrated only in the case of bivalent binding with a functional affinity constant of Kd = 2.14 x 10(-9) M-1. This implied up to a 10(4) difference between intrinsic and functional affinity, as in the range of concentration used in this study MAb 202 did not react with monomeric IgM.

A matrix effect in pectin-rich fruits hampers digestion of allergen by pepsin in vivo and in vitro.

BACKGROUND: It is a general belief that a food allergen should be stable to gastric digestion. Various acidic plant polysaccharides, including pectin, are ubiquitous in fruit matrixes and can form hydrogels under low-pH conditions. OBJECTIVE: The purpose of this study was to investigate the effect of hydrogel forming polysaccharide-rich fruit matrixes on in vivo gastric and in vitro pepsic digestion of fruit allergens. METHODS: Fruit extract proteins (kiwi, banana, apple and cherry) and a purified major kiwi allergen Act c 2 were digested with simulated gastric fluid in accordance with the US Pharmacopeia. In vivo experiments on kiwi fruit digestion were performed on four healthy non-atopic volunteers by examining the gastric content 1 h after ingestion of kiwi fruit. The Act c 2 and kiwi proteins were detected in immunoblots using monoclonal anti-Act c 2 antibodies and rabbit polyclonal antisera. RESULTS: Crude fruit extracts were resistant to digestion by pepsin when compared with commonly prepared extracts. In the gastric content of all volunteers, following kiwi fruit ingestion and immunoblotting, intact Act c 2 was detected with anti-Act c 2 monoclonal antibodies, while kiwi proteins of higher molecular weights were detected using rabbit polyclonal antisera. Addition of apple fruit pectin (1.5% and 3%) to the purified kiwi allergen was able to protect it from pepsin digestion in vitro. CONCLUSION: The matrix effect in pectin-rich fruits can influence the digestibility of food proteins and thereby the process of allergic sensitization in atopic individuals.

Bronchial epithelium-associated pulmonary arterial muscle relaxation in the rat is absent in the fetus and suppressed by postnatal hypoxia.

We recently reported the existence of a bronchial epithelium-derived relaxing factor (BrEpRF) capable of reducing pulmonary arterial smooth muscle force generation in the newborn rat. We reasoned in this study that BrEpRF has physiological significance in the control of pulmonary vascular tone. We hypothesized that the release and/or activity of this factor can be stimulated and is suppressed prenatally or under hypoxic conditions postnatally. Therefore, we evaluated the pathways stimulated by the BrEpRF in fetal and newborn rat intrapulmonary arteries mounted with their adjacent bronchi in a wire myograph under both normoxic and hypoxic conditions. Under normoxic conditions, BrEpRF release/activation was observed in newborn vessels following methacholine stimulation of M(2) muscarinic receptors, which was mediated via a nitric oxide (NO)-dependent mechanism involving the phosphatidylinositol 3-kinase pathway. Hypoxia suppressed the BrEpRF-dependent modulation of basal and methacholine-induced pulmonary arterial muscle tone in newborn vessels without altering endothelium-dependent or -independent NO-mediated relaxation. In fetal pulmonary arteries studied under normoxic conditions, BrEpRF neither was active under basal conditions nor could it be stimulated with methacholine. We conclude that release/activation of the BrEpRF occurs by an oxygen-dependent mechanism in the newborn and is suppressed during late fetal life. These results suggest that the BrEpRF may be involved in postnatal adaptation of the pulmonary circulation and that its suppression may contribute to hypoxic pulmonary vasoconstriction.

Minimal haemolysis in blood co-infused with amino acid and dextrose solutions in vitro.

OBJECTIVE: To examine the haemolytic effects of amino acid and dextrose solutions on co-infused packed red blood cells. METHODOLOGY: An in vitro study of packed cells co-infused at various rates with dextrose 5%, 10%, 15% and intravenous amino acid solution (Vamin; Kabi-Pharmacia, Baxter Healthcare Pty Ltd) in dextrose 5%, 10% and 15%. The degree of haemolysis was measured as free oxyhaemoglobin by spectrophotometer. Co-infused 0.9% saline and water were used as 0% and 100% haemolysis controls. RESULTS: Only minimal haemolysis was observed with the solutions tested. The greatest observed amount of haemolysis was 0.14%. CONCLUSIONS: Co-infusion of packed red blood cells with dextrose and amino acid solutions at the concentrations and infusion rates commonly used in neonatal care, does not cause clinically important haemolysis.

Favourable neurological outcomes following delivery room cardiopulmonary resuscitation of infants < or = 750 g at birth.

OBJECTIVE: To study short- and long-term outcomes of infants < or = 750 g birthweight who received cardiopulmonary resuscitation (CPR) in the delivery room. METHODOLOGY: A retrospective analysis of all inborn live births < or = 750 g birthweight from 1990 to 1996. Cardiopulmonary resuscitation was defined as positive pressure ventilation via an endotracheal tube and chest compressions. Univeriate analysis were conducted comparing patients according to the use of CPR or positive pressure ventilation alone. RESULTS: Cardiopulmonary resuscitation was administered to 16 infants: four received chest compressions only and 12 also received adrenaline. Cardiopulmonary resuscitation recipients had significantly lower Apgar scores at both 1 and 5 min, and had delayed onset of spontaneous respiration (P < 0.01). Seven patients died, and eight of nine survivors were free of major neurodevelopmental abnormalities at follow up. All CPR recipients with a 5 min Apgar score of < or = 5 and delayed onset of spontaneous respiration beyond 5 min had poor outcomes. CONCLUSION: Contrary to the majority of published evidence, delivery room CPR in our extremely small infants was not associated with a high risk of severe neurodevelopmental disability.

Antioxidants as therapy in the newborn: some words of caution.

Reactive oxygen and nitrogen species are considered to play a major role in the pathogenesis of a wide range of human disorders. This may be a particularly important pathogenetic mechanism in the newborn nursery. The phrase "oxygen radical disease of prematurity" has been coined to collectively describe a wide range of neonatal disorders based on the belief that premature newborns are deficient in antioxidant defenses at a time when they are subjected to acute and chronic oxidant stresses. This belief has led to a number of clinical trials of antioxidant therapies being undertaken in neonatal patients. The realization that reactive oxygen species play a critical role in neonatal illnesses has only recently been paralleled by an increased understanding of their physiologic roles. A major concern is that effective scavenging of reactive oxygen species, to attenuate their toxic effects, will also inhibit essential cellular functions such as growth in potential target organs such as lung, brain, intestine, and retina.