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Epithelial cell functions ultimately define the ability of the extremely low birth weight human fetus to survive outside of the uterus. These specialized epithelial cell capacities manage all human interactions with the ex utero world including: (i) lung mechanics, surface chemistry and gas exchange, (ii) renal tubular balance of fluid and electrolytes, (iii) barrier functions of the intestine and skin for keeping bacteria out and water in, plus enabling intestinal digestion, as well as (iv) maintaining an intact neuroepithelium lining of the ventricles of the brain and retina. In Part I of this two part review, the authors describe why the gut barrier is a clinically relevant model system for studying the complex interplay between innate and adaptive immunity, dendritic &epithelial cell interactions, intraepithelial lymphocytes, M-cells, as well as the gut associated lymphoid tissues where colonization after birth, clinician feeding practices, use of antibiotics as well as exposure to prebiotics, probiotics and maternal vaginal flora all program the neonate for a life-time of immune competence distinguishing "self" from foreign antigens. These barrier defense capacities become destructive during disease processes like necrotizing enterocolitis (NEC) when an otherwise maturationally normal, yet dysregulated and immature, immune defense system is associated with high levels of certain inflammatory mediators like TNFa. In Part II the authors discuss the rationale for why rhG-CSF has theoretical advantages in managing NEC or sepsis by augmenting neonatal neutrophil number, neutrophil expression of Fcg and complement receptors, as well as phagocytic function and oxidative burst. rhG-CSF also has potent anti-TNFa functions that may serve to limit extension of tissue destruction while not impairing bacterial killing capacity. Healthy, non-infected neutropenic and septic neonates differ in their ability to respond to rhG-CSF; however, no neonatal clinical trials to date have identified a clear clinical benefit of rhG-CSF therapy. This manuscript will review the literature and evidence available for identifying the ideal subject for cytokine treatment using NEC as the model disease target. [ABSTRACT FROM AUTHOR]

Epithelial cell functions ultimately define the ability of the extremely low birth weight human fetus to survive outside of the uterus. These specialized epithelial cell capacities manage all human interactions with the ex utero world including: (i) lung mechanics, surface chemistry and gas exchange, (ii) renal tubular balance of fluid and electrolytes, (iii) barrier functions of the intestine and skin for keeping bacteria out and water in, plus enabling intestinal digestion, as well as (iv) maintaining an intact neuroepithelium lining of the ventricles of the brain and retina. In Part I of this two part review, the authors describe why the gut barrier is a clinically relevant model system for studying the complex interplay between innate and adaptive immunity, dendritic &epithelial cell interactions, intraepithelial lymphocytes, M-cells, as well as the gut associated lymphoid tissues where colonization after birth, clinician feeding practices, use of antibiotics as well as exposure to prebiotics, probiotics and maternal vaginal flora all program the neonate for a life-time of immune competence distinguishing "self" from foreign antigens. These barrier defense capacities become destructive during disease processes like necrotizing enterocolitis (NEC) when an otherwise maturationally normal, yet dysregulated and immature, immune defense system is associated with high levels of certain inflammatory mediators like TNFa. In Part II, the authors will discuss the theoretical advantages of using rhG-CSF in managing NEC or sepsis by augmenting neonatal neutrophil number and killing capacity including an unexpected, paradoxical and potent anti-TNFa function that may serve to limit extension of tissue destruction without impairing bacterial killing capacity. The authors conclude by arguing that NEC may be the ideal disease process for testing whether a clearly defined clinical benefit of cytokine therapy can prove beneficial. [ABSTRACT FROM AUTHOR]

OBJECTIVE: Extremely low birth weight (ELBW) infants often acquire catheter-related infections (CRIs) when a percutaneously inserted central catheter (PICC) is used for parenteral nutrition or drug administration. Our objective was to compare the incidence of CRIs after we established a 'PICC Maintenance Team' for the proactive management--compared to expectant management--of these lines. STUDY DESIGN: We did a prospective collection and analysis of catheter-related sepsis data over a 15-month period from February 1, 1998 through May 1, 1999. Eligible patients included all neonates weighing <1000 g at birth. RESULTS: There was a significantly decreased incidence of CRIs, to a rate of 7.1%, or 5.1/1000 catheter days (p<0.05). CONCLUSION: 'Proactive' management of PICC, significantly reduced the incidence of CRIs. The reduction in infection rate is estimated to save 180 hospitalized patient days/100 very low birth weight neonates, with a concomitant savings in morbidity and medical expense. [ABSTRACT FROM AUTHOR]

Intraventricular hemorrhage (IVH) is a common complication in premature infants and is associated with white matter injury and long-term neurodevelopmental disabilities. Standard diagnostic tools such as cranial ultrasound and MRI are widely used in both preclinical drug development and clinical practice to detect IVH. However, these methods only provide endpoint assessments of blood accumulation and lack real-time information about dynamic changes in ventricular blood flow. This limitation could potentially result in missed opportunities to advance drug candidates that may have protective effects against IVH. In this pilot study, we aimed to develop a noninvasive optical approach using diffuse correlation spectroscopy (DCS) to monitor real-time hemodynamic changes associated with hemorrhagic and sub-hemorrhagic events in a preclinical rabbit model of IVH. DCS measurements were conducted during the experimental induction of IVH, and results were compared with ultrasound and histological analysis to validate findings. Significant changes in hemodynamics were detected in all animals subjected to IVH-inducing procedures, including those that did not show clear positive results on ultrasound. The study revealed progressively elevated coefficients of variation in blood flow, particularly driven by increased oscillations within the 0.05-0.1 Hz frequency band. These hemodynamic changes were more pronounced in animals that developed IVH, as confirmed by ultrasound. Our findings suggest that real-time optical monitoring with DCS can provide critical insights into pathological blood flow changes, offering a more sensitive and informative tool for evaluating potential therapeutics in the context of IVH.

The microbiome co-evolved with their mammalian host over thousands of years. This commensal relationship serves a pivotal role in various metabolic, physiological, and immunological processes. Recently we discovered impaired adrenal catecholamine stress responses in germ-free mice suggesting developmental modification of the reflex arc or absence of an ongoing microbiome signal. To determine whether maturational arrest or an absent bacteria-derived metabolite was the cause, we tested whether depleting gut microbiome in young adult animals could also alter the peripheral stress responses to insulin-induced hypoglycemia. Groups of C57Bl6 male mice were given regular water (control) or a cocktail of non-absorbable broad-spectrum antibiotics (Abx) in the drinking water for two weeks before injection with insulin or saline. Abx mice displayed a profound decrease in microbial diversity and abundance of Bacteroidetes and Firmicutes, plus a markedly enlarged caecum and no detectable by-products of bacterial fermentation (sp. short chain fatty acids, SCFA). Tonic and stress-induced epinephrine levels were attenuated. Recolonization (Abx + R) restored bacterial diversity, but not the sympathoadrenal system responsiveness or caecal acetate, propionate and butyrate levels. In contrast, corticosterone (HPA) and glucagon (parasympathetic) resting values and responses to hypoglycemia remained similar across all conditions. Oral supplementation with SCFA improved epinephrine responses to hypoglycaemia. Whole genome shotgun sequence profiling of fecal samples from control, Abx and Abx + R cohorts identified nine microbes (SCFA producers) absent from both Abx and Abx + R groups. These results implicate gut microbiome depletion plus its attendant reduction in SCFA signalling in adversely affecting the release of epinephrine in response to hypoglycemia. We speculate that regardless of postnatal age, a mutable microbiome messaging system exists throughout life. Unravelling these mechanisms could lead to new therapeutic possibilities through controlled manipulation of the gut microbiota and its ability to alter systemic neurotransmitter responsiveness., Competing Interests: The authors have declared that no conflict of interest exists., (© 2021 The Authors.)

Importance: Extremely preterm infants are among the populations receiving the highest levels of transfusions. Erythropoietin has not been recommended for premature infants because most studies have not demonstrated a decrease in donor exposure., Objectives: To determine whether high-dose erythropoietin given within 24 hours of birth through postmenstrual age of 32 completed weeks will decrease the need for blood transfusions., Design, Setting, and Participants: The Preterm Erythropoietin Neuroprotection Trial (PENUT) is a randomized, double-masked clinical trial with participants enrolled at 19 sites consisting of 30 neonatal intensive care units across the United States. Participants were born at a gestational age of 24 weeks (0-6 days) to 27 weeks (6-7 days). Exclusion criteria included conditions known to affect neurodevelopmental outcomes. Of 3266 patients screened, 2325 were excluded, and 941 were enrolled and randomized to erythropoietin (n = 477) or placebo (n = 464). Data were collected from December 12, 2013, to February 25, 2019, and analyzed from March 1 to June 15, 2019., Interventions: In this post hoc analysis, erythropoietin, 1000 U/kg, or placebo was given every 48 hours for 6 doses, followed by 400 U/kg or sham injections 3 times a week through postmenstrual age of 32 weeks., Main Outcomes and Measures: Need for transfusion, transfusion numbers and volume, number of donor exposures, and lowest daily hematocrit level are presented herein., Results: A total of 936 patients (488 male [52.1%]) were included in the analysis, with a mean (SD) gestational age of 25.6 (1.2) weeks and mean (SD) birth weight of 799 (189) g. Erythropoietin treatment (vs placebo) decreased the number of transfusions (unadjusted mean [SD], 3.5 [4.0] vs 5.2 [4.4]), with a relative rate (RR) of 0.66 (95% CI, 0.59-0.75); the cumulative transfused volume (mean [SD], 47.6 [60.4] vs 76.3 [68.2] mL), with a mean difference of -25.7 (95% CI, 18.1-33.3) mL; and donor exposure (mean [SD], 1.6 [1.7] vs 2.4 [2.0]), with an RR of 0.67 (95% CI, 0.58-0.77). Despite fewer transfusions, erythropoietin-treated infants tended to have higher hematocrit levels than placebo-treated infants, most noticeable at gestational week 33 in infants with a gestational age of 27 weeks (mean [SD] hematocrit level in erythropoietin-treated vs placebo-treated cohorts, 36.9% [5.5%] vs 30.4% [4.6%] (P < .001). Of 936 infants, 160 (17.1%) remained transfusion free at the end of 12 postnatal weeks, including 43 in the placebo group and 117 in the erythropoietin group (P < .001)., Conclusions and Relevance: These findings suggest that high-dose erythropoietin as used in the PENUT protocol was effective in reducing transfusion needs in this population of extremely preterm infants., Trial Registration: ClinicalTrials.gov Identifier: NCT01378273.

Background: High-dose erythropoietin has been shown to have a neuroprotective effect in preclinical models of neonatal brain injury, and phase 2 trials have suggested possible efficacy; however, the benefits and safety of this therapy in extremely preterm infants have not been established., Methods: In this multicenter, randomized, double-blind trial of high-dose erythropoietin, we assigned 941 infants who were born at 24 weeks 0 days to 27 weeks 6 days of gestation to receive erythropoietin or placebo within 24 hours after birth. Erythropoietin was administered intravenously at a dose of 1000 U per kilogram of body weight every 48 hours for a total of six doses, followed by a maintenance dose of 400 U per kilogram three times per week by subcutaneous injection through 32 completed weeks of postmenstrual age. Placebo was administered as intravenous saline followed by sham injections. The primary outcome was death or severe neurodevelopmental impairment at 22 to 26 months of postmenstrual age. Severe neurodevelopmental impairment was defined as severe cerebral palsy or a composite motor or composite cognitive score of less than 70 (which corresponds to 2 SD below the mean, with higher scores indicating better performance) on the Bayley Scales of Infant and Toddler Development, third edition., Results: A total of 741 infants were included in the per-protocol efficacy analysis: 376 received erythropoietin and 365 received placebo. There was no significant difference between the erythropoietin group and the placebo group in the incidence of death or severe neurodevelopmental impairment at 2 years of age (97 children [26%] vs. 94 children [26%]; relative risk, 1.03; 95% confidence interval, 0.81 to 1.32; P = 0.80). There were no significant differences between the groups in the rates of retinopathy of prematurity, intracranial hemorrhage, sepsis, necrotizing enterocolitis, bronchopulmonary dysplasia, or death or in the frequency of serious adverse events., Conclusions: High-dose erythropoietin treatment administered to extremely preterm infants from 24 hours after birth through 32 weeks of postmenstrual age did not result in a lower risk of severe neurodevelopmental impairment or death at 2 years of age. (Funded by the National Institute of Neurological Disorders and Stroke; PENUT ClinicalTrials.gov number, NCT01378273.)., (Copyright © 2020 Massachusetts Medical Society.)

Objective: To determine the effects of sodium bicarbonate (NaHCO3) correction of metabolic acidosis on cardiopulmonary, laboratory, and cerebral, renal and splanchnic regional oxygen saturation (rSO2) and fractional tissue oxygen extraction (FTOE) in extremely premature neonates during the first postnatal week., Study Design: Observational cohort data were collected from 500 to 1250 g neonates who received NaHCO3 'half' corrections (0.3 * Weight (kg) * Base Deficit (mmol l(-1))) for presumed renal losses., Result: Twelve subjects with normal blood pressure and heart rate received 17 NaHCO3 corrections. Mean (±s.d.) gestational age was 27±2 week and birth weight was 912±157 g. NaHCO3 corrections provided a mean (±s.d.) 4.5±1.0 ml kg(-1) fluid bolus, shifted mean (±s.d.) base deficit from 7.6±1.8 to 3.4±2.1 mmol l(-1) (P<0.05), and increased median (±s.d.) pH from 7.23±0.06 to 7.31±0.05 (P<0.05). No significant changes in blood pressure, pulse oximetry, PCO2, lactate, sodium, blood urea nitrogen, creatinine or hematocrit were observed. Cerebral, renal and splanchnic rSO2 (74%, 66% and 44%, respectively, at baseline) and FTOE (0.21, 0.29 and 0.52, respectively, at baseline) were unchanged following NaHCO3 correction., Conclusion: NaHCO3 infusions decreased base deficits and increased pH though produced no discernible effects or benefits on cardiopulmonary parameters including rSO2 and FTOE. These findings warrant further prospective evaluation in larger populations with more significant metabolic acidosis to determine the utility of tissue oxygenation monitoring in differentiating metabolic acidosis due to oxygen delivery/consumption imbalance versus renal bicarbonate losses.

Postnatal glucocorticoids (GCs) are widely used in the prevention of chronic lung disease in premature infants. Their pharmacologic use is associated with neurodevelopmental delay and cerebral palsy. However, the effect of GC dose and preparation (dexamethasone versus betamethasone) on short and long-term neurological outcomes remains undetermined, and the mechanisms of GC-induced brain injury are unclear. We hypothesized that postnatal GC would induce hypomyelination and motor impairment in a preparation- and dose-specific manner, and that GC receptor (GR) inhibition might restore myelination and neurological function in GC-treated animals. Additionally, GC-induced hypomyelination and neurological deficit might be transient. To test our hypotheses, we treated prematurely delivered rabbit pups with high (0.5mg/kg/day) or low (0.2mg/kg/day) doses of dexamethasone or betamethasone. Myelin basic protein (MBP), oligodendrocyte proliferation and maturation, astrocytes, transcriptomic profile, and neurobehavioral functions were evaluated. We found that high-dose GC treatment, but not low-dose, reduced MBP expression and impaired motor function at postnatal day 14. High-dose dexamethasone induced astrogliosis, betamethasone did not. Mifepristone, a GR antagonist, reversed dexamethasone-induced myelination, but not astrogliosis. Both GCs inhibited oligodendrocyte proliferation and maturation. Moreover, high-dose dexamethasone altered genes associated with myelination, cell-cycle, GR, and mitogen-activated protein kinase. Importantly, GC-induced hypomyelination, gliosis, and motor-deficit, observed at day 14, completely recovered by day 21. Hence, high-dose, but not low-dose, postnatal GC causes reversible reductions in myelination and motor functions. GC treatment induces hypomyelination by GR-dependent genomic mechanisms, but astrogliosis by non-genomic mechanisms. GC-induced motor impairment and neurodevelopmental delay might be transient and recover spontaneously in premature infants., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Recurrent exposure to hypoglycemia can impair the normal counterregulatory hormonal responses that guard against hypoglycemia, leading to hypoglycemia unawareness. This pathological condition known as hypoglycemia-associated autonomic failure (HAAF) is the main adverse consequence that prevents individuals with type 1 diabetes mellitus from attaining the long-term health benefits of tight glycemic control. The underlying molecular mechanisms responsible for the progressive loss of the epinephrine response to subsequent bouts of hypoglycemia, a hallmark sign of HAAF, are largely unknown. Normally, hypoglycemia triggers both the release and biosynthesis of epinephrine through activation of nicotinic acetylcholine receptors (nAChR) on the adrenal glands. We hypothesize that excessive cholinergic stimulation may contribute to impaired counterregulation. Here, we tested whether administration of the nAChR partial agonist cytisine to reduce postganglionic synaptic activity can preserve the counterregulatory hormone responses in an animal model of HAAF. Compared with nicotine, cytisine has limited efficacy to activate nAChRs and stimulate epinephrine release and synthesis. We evaluated adrenal catecholamine production and secretion in nondiabetic rats subjected to two daily episodes of hypoglycemia for 3 days, followed by a hyperinsulinemic hypoglycemic clamp on day 4. Recurrent hypoglycemia decreased epinephrine responses, and this was associated with suppressed TH mRNA induction (a measure of adrenal catecholamine synthetic capacity). Treatment with cytisine improved glucagon responses as well as epinephrine release and production in recurrently hypoglycemic animals. These data suggest that pharmacological manipulation of ganglionic nAChRs may be promising as a translational adjunctive therapy to avoid HAAF in type 1 diabetes mellitus., (Copyright © 2014 the American Physiological Society.)

Background: Thyroid hormones are required for normal brain maturation, and neonatal plasma thyroid hormone concentrations are low in infants less than 28 weeks gestation. It is not known whether treatment of such infants with thyroid hormone improves neurodevelopmental outcome., Methods: At three years corrected age, mental, motor, and neurological development was assessed in infants born at less than 28 weeks gestational age who had participated in a phase 1 trial of differing doses and modes of administration of thyroid hormone. The trial's endpoints were thyroid hormone (thyroxine, T4) and thyotropin plasma concentrations in eight study arms: six treated with T4 [4, 8, and 16 μg/(kg · day)], bolus or continuous], one treated with iodine only, and one treated with placebo. Follow-up at three years was not part of the original study goals. Developmental index scores, rates of cerebral palsy (CP), and rates of adverse outcome (death or moderate to severe delay in development and/or disabling CP) were compared between the eight study groups and between groups combined by dosage level, and between infants with and without T4 supplementation., Results: Of 166 randomized infants, 32 (19%) died in the neonatal period. Of the 134 survivors, follow-up results were available for 89 children (66%). Mental and motor development and rates of cerebral palsy did not differ in any of the comparisons made., Conclusion: In this study, no differences in neurodevelopment were found in relation to thyroid hormone treatment, but power was insufficient to detect any but very large differences.

Objective: We sought to characterize the effects of "booster" packed red blood cell transfusions on multisite regional oxygen saturation in very low birth weight neonates during the first postnatal week and to examine the utility of fractional tissue oxygen extraction as an estimate of tissue oxygenation adequacy., Study Design: Data were collected in an observational near-infrared spectroscopy (NIRS) pilot survey of 500-1250 g neonates during the first postnatal week. A before-after analysis of "booster" transfusions, defined as empiric 15 mL/kg transfusion following 10 mL/kg cumulative phlebotomy losses, was conducted upon cardiopulmonary, laboratory, and spectroscopy data., Result: Ten neonates (gestational age 26 ± 0 wk; birth weight 879 ± 49 g) received 14 transfusions at 3 ± 0 postnatal days. Mean hematocrit increased from 35.2 ± 1.2 to 38.5 ± 1.2 % (P < 0.05) following transfusion; pH, base deficit, lactate, creatinine, and cardiopulmonary parameters were unchanged. Cerebral, renal, and splanchnic tissue oxygenation increased 10, 18, and 16%, with concomitant decreases in calculated oxygen extraction of 27, 30, and 9% (all P < 0.05), consistent with enhanced tissue oxygenation. These findings were not observed in a non-transfused comparison group of nine patients., Conclusion: "Booster" transfusions improved indices of regional tissue oxygenation while no departures were observed in conventional cardiovascular assessments. We speculate that NIRS-derived oxygenation parameters can provide an objective, graded, and continuous estimate of oxygen delivery-consumption balance not evident using standard monitoring techniques.

Objective: In extremely premature neonates, data concerning the normal baseline variability of near-infrared spectroscopy (NIRS)-derived regional oxygen saturation (rSO2) are lacking. We sought to determine: 1) the quiescent variability of cerebral, renal, and splanchnic rSO2 in clinically stable, undisturbed very low birth weight neonates and 2) the effects of different data averaging epochs on site-specific variability., Study Design: In this prospective, observational study, neonates between 500 and 1250 g underwent seven days of continuous, real-time cerebral, renal, and splanchnic NIRS monitoring starting within the first seventy-two postnatal hours. Demographic, cardiopulmonary, bedside care, and rSO2 data were collected. rSO2 variability was analyzed utilizing data from quiescent periods identified using pre-specified stability criteria. Between- and within-monitoring site comparisons of data averaging methods were made utilizing ANOVA., Result: Twenty-four subjects (GA 27 ± 0.3 wk, birth weight 988 ± 34 g; mean ± SEM) were monitored. Coefficients of variation (CoVar = SD/mean) were calculated for each monitoring site using varied data averaging epochs. CoVar was lowest for cerebral, intermediate for renal, and highest for splanchnic rSO2 (P < 0.01). For renal and splanchnic sites, shorter epochs (5- and 15-min) resulted in significantly smaller CoVars [P < 0.01 and P < 0.05, respectively]. Splanchnic variability was highly dependent on epoch length, ranging from 16% over 5 min to 23% over 60 min., Conclusion: 1) rSO2 variability differs significantly between monitoring sites and 2) shorter data sampling epochs decrease rSO2 variability. These observations may assist clinicians in operationally defining minimally significant departures to enable medical decision making utilizing this monitoring technique.

Hemophagocytic lymphohistiocytosis (HLH) is a systemic disease resulting from the excessive release of inflammatory cytokines by macrophages under prolonged antigenic stimulation. If untreated, it leads to multiorgan failure and death. Necrotizing enterocolitis (NEC) has not previously been associated with HLH. Here we report four preterm infants who were diagnosed with HLH associated with NEC. Two patients received chemotherapy and one survived. The other two infants succumbed to multiorgan failure. These results suggest that NEC may be a common clinical manifestation of HLH in premature neonates., (Copyright © 2012 Wiley Periodicals, Inc.)

Repeated stress is a major public health concern where many stress responses are mediated by neuronal nicotinic acetylcholine receptors. In the present study we evaluated the effects of the nicotinic receptor partial agonists, cytisine and its derivative 3-(pyridin-3'-yl)-cytisine (3-pyr-Cyt) on two main biological outputs associated with activation of nAChR-release of neurotransmitters and increase in catecholamine biosynthesis to replenish the releasable pool. We compared these substances to the maximal response triggered by nicotine (full agonist) in PC12 cells. Cytisine, 3-pyr-Cyt or nicotine induced time-, dose- and Ca(2+)-dependent significant release of norepinephrine (NE) into the culture media. These effects were completely inhibited by mecamylamine but not by α-bungarotoxin, and only partially affected by α-conotoxin AulB, consistent with the involvement of α3β4 receptors. Co-application of cytisine (or 3-pyr-Cyt) and nicotine resulted in attenuated nicotine-induced NE release. Cytisine or 3-pyr-Cyt alone induced a modest rise in tyrosine hydroxylase (TH) mRNA levels (index of the cell's catecholamine biosynthetic capacity). We conclude that both, cytisine and 3-pyr-Cyt (i) display typical partial agonist properties at naturally existing ganglionic nAChR (α3β4 and α7 nAChR) with regard to catecholamine homeostasis (i.e. NE release and re-synthesis) and (ii) modulated the effect of nicotine during combined treatment., (Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.)

We investigated the stability of thyroid hormones during a mode of continuous drug infusion via polypropylene tubing using the same conditions that would be applied to treating patients in a hospital setting. The diluted thyroid hormones were prepared using aseptic technique, stored at 2-8°C (36-46°F) and tested within 24 h of preparation for stability and percent recovery from within plastic tubing. Experiments were done in duplicate with triplicate sets of readings for each assay point. Only T(4) prepared with 5% dextrose water (D5W) containing 1 mg/mL albumin remained constant, stable, predictable and accurate over time under various conditions. Other methods of preparation lost drug by adhering to the plastic containers and tubing by as much as 40% of starting concentration. T(3) recovery in the presence of 1 mg/mL of albumin was 107±2% (mean±standard error of the mean) of anticipated drug concentrations. We conclude from this series of experiments that to maintain an accurate and stable dosing of patients receiving intravenous thyroid hormones, 1 mg/mL of albumin must be added to the infusate to prevent lost on the plastic intravenous tubing.

Intraventricular haemorrhage is a major complication of prematurity that results in neurological dysfunctions, including cerebral palsy and cognitive deficits. No therapeutic options are currently available to limit the catastrophic brain damage initiated by the development of intraventricular haemorrhage. As intraventricular haemorrhage leads to an inflammatory response, we asked whether cyclooxygenase-2, its derivative prostaglandin E2, prostanoid receptors and pro-inflammatory cytokines were elevated in intraventricular haemorrhage; whether their suppression would confer neuroprotection; and determined how cyclooxygenase-2 and cytokines were mechanistically-linked. To this end, we used our rabbit model of intraventricular haemorrhage where premature pups, delivered by Caesarian section, were treated with intraperitoneal glycerol at 2 h of age to induce haemorrhage. Intraventricular haemorrhage was diagnosed by head ultrasound at 6 h of age. The pups with intraventricular haemorrhage were treated with inhibitors of cyclooxygenase-2, prostanoid receptor-1 or tumour necrosis factor-α; and cell-infiltration, cell-death and gliosis were compared between treated-pups and vehicle-treated controls during the first 3 days of life. Neurobehavioural performance, myelination and gliosis were assessed in pups treated with cyclooxygenase-2 inhibitor compared to controls at Day 14. We found that both protein and messenger RNA expression of cyclooxygenase-2, prostaglandin E2, prostanoid receptor-1, tumour necrosis factor-α and interleukin-1β were consistently higher in the forebrain of pups with intraventricular haemorrhage relative to pups without intraventricular haemorrhage. However, cyclooxygenase-1 and prostanoid receptor 2-4 levels were comparable in pups with and without intraventricular haemorrhage. Cyclooxygenase-2, prostanoid receptor-1 or tumour necrosis factor-α inhibition reduced inflammatory cell infiltration, apoptosis, neuronal degeneration and gliosis around the ventricles of pups with intraventricular haemorrhage. Importantly, cyclooxygenase-2 inhibition alleviated neurological impairment, improved myelination and reduced gliosis at 2 weeks of age. Cyclooxygenase-2 or prostanoid receptor-1 inhibition reduced tumour necrosis factor-α level, but not interleukin-1β. Conversely, tumour necrosis factor-α antagonism did not affect cyclooxygenase-2 expression. Hence, prostanoid receptor-1 and tumour necrosis factor-α are downstream to cyclooxygenase-2 in the inflammatory cascade induced by intraventricular haemorrhage, and cyclooxygenase-2-inhibition or suppression of downstream molecules--prostanoid receptor-1 or tumour necrosis factor-α--might be a viable neuroprotective strategy for minimizing brain damage in premature infants with intraventricular haemorrhage.

Background: Despite advances in the care of neonates with gastroschisis, patients present with significant morbidities. Preterm delivery of neonates with gastroschisis is often advocated to avoid the intestinal damage that may be sustained with prolonged exposure to amniotic fluid. However, preterm delivery may impose additional morbidities to this disease process., Methods: We conducted a retrospective review of patients with gastroschisis born from 1989 to 2007. Demographic and clinical data were collected. Preterm healthy neonates, with gestational age from 26 to 36 weeks, were used as controls., Results: Preterm infants with gastroschisis had a 14 times higher risk for any of the recorded morbidities. As compared to term neonates with gastroschisis, preterm neonates with gastroschisis had a higher rate of sepsis, longer duration to reach full enteral feedings, and longer length of stay. Although the preterm infants with gastroschisis were less likely to be small for gestational age at birth, they were as likely as the term infants with gastroschisis to have failure to thrive at discharge and had a greater drop in weight percentile during hospitalization., Conclusions: Preterm delivery should be avoided because there is no clear benefit to the gut in avoiding derivative injuries. Meticulous attention should be given to the nutritional needs of patients with gastroschisis.

Parainfluenza virus (PIV) causes > 30% of all acute respiratory infections in infants and children and is second only to respiratory syncytial virus as a cause of lower respiratory tract infection. However in the neonatal intensive care unit (NICU), PIV outbreaks are highly uncommon. This case report describes an outbreak of 3 cases of PIV type 3 in a regional NICU.

Objective: As effects of glucocorticoids differ with respect to preparation, dose and duration, we hypothesized that a postnatal regimen of a low-dose, short-course betamethasone treatment had comparable efficacy and a better safety profile compared to the conventional high-dose, dexamethasone., Study Design: To test our hypothesis, we selected premature neonates with a birth weight 10 postnatal days with an FiO(2)>0.4 and no ability to wean mechanical support for >or=3 consecutive days. These neonates either received twice daily dexamethasone 0.25 mg kg(-1) per dose intravenously for 3 days tapered to 0.125 mg kg(-1) per dose for 4 days (June 1999 to December 2000) or betamethasone 0.125 mg kg(-1) per day intramuscularly once per day for 3 days (January 2001 to December 2002)., Result: We found a significant reduction in FiO(2) after 3 days in both glucocorticoid treatment groups. There were no significant differences between the two treatment groups in the clinical parameters including decrease in FiO(2), oxygenation index, mean airway pressure and percent extubation. Duration of ventilation, number of oxygen days and length of hospital stay were comparable in the two groups. Of particular interest, the betamethasone group showed fewer adverse effects, such as poor weight gain and high blood glucose, than the dexamethasone group., Conclusion: A short course of low-dose betamethasone has comparable efficacy and seemingly a better short-term safety profile compared to conventional dexamethasone treatment.

Objective: We describe the first outbreak of multiple drug-resistant Acinetobacter baumannii (MDR-Ab) in a neonatal intensive care unit in the United States., Design/methods: MDR-Ab was identified in the blood of a 24-week gestation, 7-day-old extremely low birth weight neonate. Multiple samplings of surveillance surface cultures were performed on exposed and nonexposed neonates. Enhanced infection control measures were implemented. Pulsed-field gel electrophoresis was performed to determine the genetic relatedness of the MDR-Ab isolates. Medical records were reviewed for all exposed patients., Results: MDR-Ab was recovered from 6 additional neonates. Of these 7 MDR-Ab (index + 6) neonates, 4 died, 3 of whom had positive blood cultures. All affected neonates were born between 23 to 26 weeks gestational age, and were <7 days postnatal age and <750 g (430-720) at the time of exposure. All were housed within the same room as the index case. None of the other 5 exposed neonates older than postnatal day 7 or weighing >750 g at birth were affected. No additional cases occurred outside the original room. Pulsed-field gel electrophoresis was consistent with a clonal origin, identical to MDR-Ab recovered from the referring hospital., Conclusions: This MDR-Ab outbreak was rapidly controlled with enhanced infection control measures and was novel in that it affected only <750 g neonates, at < or =26 weeks gestational age, and < or =7 days postnatal age at the time of exposure, suggesting that invasive Ab has a special affinity for damaged or nonkeratinized immature skin in developmentally immature immunologic hosts.

Germinal matrix is selectively vulnerable to hemorrhage in premature infants, and use of prenatal betamethasone is associated with a lower occurrence of germinal matrix hemorrhage. Because the major components of extracellular matrix of the cerebral vasculature-laminin, fibronectin, collagen IV, and perlecan-provide structural stability to blood vessels, we examined whether the expression of these molecules was decreased in the germinal matrix and affected by betamethasone. In both human fetuses and premature infants, fibronectin was significantly lower in the germinal matrix than in the cortical mantle or white matter anlagen. Conversely, laminin alpha1 gene expression was greater in the human germinal matrix compared with the cortical mantle or white matter. Expression of alpha1- and alpha2(IV) collagen chains increased with advancing gestational age. Low-dose prenatal betamethasone treatment enhanced fibronectin level by 1.5-2-fold whereas a high dose reduced fibronectin expression by 2-fold in rabbit pups. Because fibronectin provides structural stability to the blood vessels, its reduced expression in the germinal matrix may contribute to the fragility of germinal matrix vasculature and the propensity to hemorrhage in premature neonates.

Astrocyte end-feet ensheathe blood vessels in the brain and are believed to provide structural integrity to the cerebral vasculature. We sought to determine in developing infants whether the coverage of blood vessels by astrocyte end-feet is decreased in germinal matrix (GM) compared with cerebral cortex and white matter (WM), which may cause fragility of the GM vasculature. Therefore, we evaluated the perivascular coverage by astrocyte end-feet in these areas. We double-labeled the brain sections with astroglial markers [glial fibrillary acidic protein (GFAP), aquaporin-4 (AQP4), and S-100beta] and a vascular marker, laminin. Perivascular coverage by GFAP+ astrocyte end-feet increased consistently as a function of gestational age (GA) in cortex and WM from 19 to 40 wk. Compared with GFAP, AQP4+ astrocyte end-feet developed at an earlier GA, ensheathing about 63% of blood vessels for 23-40 wk in cortex, WM, and GM. Coverage by GFAP+ perivascular end-feet was decreased in GM compared with cortex and WM from 23 to 34 wk. There was no difference in the coverage by AQP4+ end-feet among the three areas in these infants. The expression of AQP4, a water channel molecule, in the astrocyte end-feet was not significantly different between premature and mature infants, suggesting similar risk of brain edema in preterm and term infants in pathologic conditions. More importantly, the lesser degree of GFAP expression in astrocyte end-feet of GM compared with cortex and WM may reflect a cytoskeletal structural difference that contributes to the fragility of GM vasculature and propensity to hemorrhage.

Butyrate is a diet-derived, gut fermentation product with an array of effects on cultured mammalian cells including inhibition of proliferation, induction of differentiation and regulation of gene expression. We showed that physiological concentrations of butyrate can regulate transcription of tyrosine hydroxylase (TH) and preproenkephalin (ppEnk) gene in PC12 cells. In promoter deletion studies, electrophoretic mobility shift assays and by site-directed mutagenesis, we identified a novel butyrate response element (BRE) in the 5' upstream region of the rat TH gene, homologous to the previously mapped motif in the ppEnk promoter. No such enhancers were found in DBH or PNMT promoters, and both catecholamine system-related gene promoters were unaffected by butyrate. The BRE motif interacts with nuclear proteins in a sequence-specific manner, shows binding potentiation in butyrate-differentiated PC12 cells and bound protein(s) are competed away with TH-CRE oligonucleotides or by the addition of CREB-specific antibodies, suggesting involvement of CREB or CREB-related transcription factors. Moreover, single point mutation in the distal BRE abolished binding of transcription factors and reduced the response to butyrate in transient transfection studies. The canonical CRE motif of the TH promoter was also found necessary for transcriptional activation of the TH gene by butyrate. Our data identified a novel functional element in the promoter of both the TH and ppEnk genes mediating transcriptional responses to butyrate. Dietary butyrate may have an extended role in the control of catecholamine and endogenous opioid production at the level of TH and ppEnk gene transcription neuronal plasticity, cardiovascular functions, stress adaptation and behavior.

Circulating short-chain fatty acids (SCFAs) are primarily derived from bacterial fermentation of carbohydrates in the colon where they function as physiologic modulators of epithelial cell maturation. Butyrate has been shown to induce tyrosine hydroxylase, the rate-limiting enzyme of catecholamine synthesis, and enkephalin neuropeptide gene transcription, suggesting a role in perinatal sympathoadrenal stress-adaptation. We sought to determine whether there were SCFA structural requirements for this effect. Nine biologically relevant SCFAs and butyrate derivatives were tested in an in vitro model (PC12, rat pheochromocytoma cells) for their ability to regulate neurotransmitter-related gene expression. Our results revealed that among all the studied SCFAs, only propionate and butyrate increased tyrosine hydroxylase and proenkephalin mRNA levels. The functional activity was selective to the carbon atom chain length and associated with the presence of an ethyl moiety in the carbon atom backbone chain. Modifications or absence of this domain affected the gene induction response, suggesting a receptor-mediated mechanism(s). Moreover, propionate, butyrate, and the drug 4-phenylbutyrate were each shown to regulate transmitter genes via at least three independent mechanisms: histone hyperacetylation, cAMP signaling, or peroxisome proliferator-activated receptor gamma-mediated pathways. Thus, the biologic impact of SCFAs on catecholaminergic and opioid systems depend on the activation of SCFA-specific, dose-specific, and gene-specific molecular mechanisms. We speculate that 1) circulating levels of SCFAs may influence sympathoadrenal transmitter biosynthesis and hence whole animal stress-adaptive responsiveness after birth, and 2) the adverse effects of antibiotics on delayed acquisition of postnatal gut flora may affect this apparent evolutionary advantage of gut colonization.

Background: Respiratory syncytial virus (RSV) is the most common respiratory pathogen in infancy and childhood., Objective: To compare the compliance and biologic efficacy of a home health care agency dosing-compliance program to treatment provided in a physician's office setting during a single RSV season (November to May). METHODS.: AAP guidelines were used to identify neonates who were eligible for RSV prophylaxis before discharge from a neonatal intensive care unit setting. Parents were asked to choose to receive the recommended treatment for their child either in their pediatrician's office setting or through a sequence of periodic nursing visits to their home. All home health care records were reviewed for demographics, number of doses received and hospitalization rate. Pediatricians office records were surveyed by telephone interview of their office staff and parents. Compliance data were calculated based on actual monthly injections given during the RSV season., Results: We followed prospectively 1446 infants who received palivizumab during a single RSV season (November 1, 2000 through April 30, 2001). Of these infants 67% (969 of 1446) received their monthly injections in the home setting where 98% of the doses were given on schedule. In contrast 477 infants (33%) received their injections in a pediatrician's office (parent's choice) with a compliance of only 89% for completion of all recommended doses (P < 0.001 vs. home setting). There were 9 RSV hospitalizations (0.93%) in the home setting group and 8 RSV hospitalizations (3.57%) in the office setting (P < 0.001). More parents indicated that the in-home prophylaxis program was more convenient than was true for those receiving treatment in the physician's office setting (P < 0.01)., Conclusions: Better compliance with home injections was associated with a decrease in the hospitalization rate for RSV with a higher degree of parental satisfaction.

We mailed a survey on treatment practices for transient hypothyroxinemia of prematurity (THOP) to 100 randomly selected neonatologists. In the year before the survey, 13 of 62 respondents (21.0%) had treated an average of 4.5 THOP patients with thyroid hormone, and 3 had treated 10 or more patients. Randomized trials assessing the value of thyroid supplementation in THOP are urgently needed.

Granulocyte colony-stimulating factor (G-CSF) increases the concentration and activation of neutrophils in the peripheral blood and has been used to prevent late-onset infection in premature infants. However, if G-CSF also augmented the inflammatory response in the lung, the incidence and severity of acute and chronic lung injury might be expected to increase. Using a newborn piglet model of acute lung injury, we examined the effects of rhG-CSF (recombinant-metHuG-CSF) on lung injury. Thirty-three newborn piglets were studied as follows: 1). Unventilated controls; 2). normally ventilated (PaCO2 = 35-45 torr) with room air(RA) for 48 h; 3). normally ventilated with RA for 48 h and received rhG-CSF (10 mg/kg/dose IV) at 0, 12, 24, and 36 h; 4). hyperventilated (PaCO2 = 15-25 torr) with 100% O2 for 48 h; 5) hyperventilated with 100% O2 for 48 h and received rhG-CSF (10 mg/kg/dose IV) at 0, 12, 24 and 36 h. Complete blood counts and and differentials were performed at 0, 24, and 48 h. Animals were sacrificed at 48 h, lungs were removed en bloc, and bronchoalveolar lavage (BAL) was performed. Total blood white blood cells and neutrophil counts increased significantly over 48 h in animals who received rhG-CSF either with normoventilation (p <0.0001) or hyperventilation with 100% O2 (p <0.003), and did not change significantly in the other experimental groups. However, there were no significant differences in BAL total cell counts, neutrophil chemotaxis activity, total protein, or albumin concentrations among the groups. Despite significantly increasing peripheral neutrophil counts, rhG-CSF did not potentiate acute lung injury or inflammation. This suggests that prophylactic administration strategies using rhG-CSF to prevent sepsis in premature infants should not increase the risk for developing acute and chronic lung disease.

Objective: Potassium is the most abundant intracellular cation and plays an important role in a variety of cell functions. Potassium homeostasis and regulation are important aspects of fluid and electrolyte homeostasis in extremely low birth weight (ELBW) infants. Because prenatal steroid (PNS) treatment promotes maturation of many epithelial cell systems, we sought to determine whether PNS affects potassium homeostasis in ELBW infants (<1000 g) during the first week of life., Method: Serum potassium (SK) concentration, potassium intake and output, and renal clearance were collected prospectively each day during the first week of life. Infants whose mothers received a full course of steroids before delivery (PNS group: n = 16) were compared with those infants whose mothers did not receive steroids (nonsteroid group [NSG]: n = 14). The decision to treat with PNS was made entirely by the obstetric staff in a nonrandomized manner. Potassium intake and excretion and serum and urine electrolytes were measured every 12 hours, and urine output was monitored every 2 to 3 hours. Hyperkalemia was defined as SK >6. 5 mmol/L in a nonhemolyzed sample on at least 1 measurement from a central line., Results: There were no significant differences between the groups in gestational age, Apgar score, and birth weight. SK increased initially after birth in the absence of exogenous K intake in all infants, then subsequently decreased and stabilized by day 4 of life. The peak SK was significantly lower in the PNS group than in the NSG group (5.2 +/-.2 mmol/L vs 6.2 +/-.4 mmol/L). Moreover, the peak SK was higher than 6.5 mmol/L in 70% of the NSG infants and in none of the PNS group. Hyperkalemia occurred in the NSG infants within the first 2 days when urine output was significantly lower than in PNS infants. SK peaked in the absence of potassium intake with similar potassium excretion in both groups. PNS infants had similar cumulative potassium intake with a lower cumulative potassium excretion than did NSG infants. PNS infants had a significantly less negative potassium balance than did NSG infants by day 7 of life (-1.0 mmol/kg vs -7.0 mmol/kg). There was no statistical difference in the daily serum creatinine levels, fractional excretion of potassium, and in the daily creatinine clearance between the 2 groups., Conclusion: We conclude that treatment with PNS prevents the nonoliguric hyperkalemia known to occur in ELBW neonates. We speculate that PNS induces upregulation of cell membrane sodium, potassium-adenosinetriphosphatase activity in the fetus. The differences in negative potassium balance may be accounted for by stabilization of cell membranes that may result in a decrease in potassium shift from intracellular to extracellular compartments.

For the dissection of the temporal and spatial patterns of cell- and tissue-specific gene expression an understanding of the contributing regulating mechanisms is required. We now confirm that there are novel mechanisms regulating preproenkephalin gene expression in basal as well as cholinergic agonist treated rats. Moreover, we demonstrate that these novel transcriptional mechanisms are consistent with RNA intragenic elongation pausing, alternate promoter usage, and small sense and antisense RNA transcription from the preproenkephalin gene locus. We report that while basal striatal and olfactory bulb proenkephalin RNA transcripts are initiated from the "normal" proximal promoter, in cerebellum de novo RNA transcription appears to be initiated from the distal so-called "germ-cell" promoter. Furthermore, "normally" initiated olfactory bulb proenkephalin RNA transcripts appear to be down-regulated by the time the RNA polymerase II complex reaches the first preproenkephalin intron, in a way that is consistent with RNA elongation pausing. As the pattern of small sense and antisense transcripts found associated with this gene's expression is tissue-specific, we suggest that they may also play a role in regulating gene expression. The understanding of this gene's regulation should have widespread importance, not only to those interested in opioid gene expression, but also to those interested in gene regulation, in general.

Catecholamines (CA) are released from and resynthesized in the adrenal medulla in response to stress. In the mature animal, stimulus-secretion-synthesis coupling occurs through transsynaptic (neuronal) activity. In contrast, in the immature animal, before functional adrenal innervation, certain stressors (hypoglycemia and glycopenia) do not result in CA release. Additionally, it is not known whether release and biosynthesis remain coupled in the neonate as they are in the adult. Therefore, to evaluate whether neonatal stressors can induce CA biosynthesis at the genomic level "directly" before function adrenal innervation, we studied the expression of the tyrosine hydroxylase (TH) gene, the rate-limiting enzyme in CA biosynthesis. Newborn rat pups were made either hypoxic, hypoglycemic, or cellularly glycopenic (2-deoxyglucose). Neither hypoxic stress nor insulin-induced hypoglycemic stress altered steady state levels of TH mRNA in the neonate. However, cellular glycopenia resulted in a significant 2-fold rise in TH mRNA levels (p < 0.05). As expected, each of these stressors increased TH mRNA levels in the mature adult rat. Thus, neonatal hypoxia and hypoglycemia appear to require intact neurogenic impulse activity, whereas cellular glycopenia may "directly" induce TH RNA, perhaps through hormonal mechanisms. This developmental model allows for the analysis of mechanisms governing adrenal CA release separate from those governing biosynthesis at the level of TH RNA. Acute neonatal hypoxic stress results in adrenal CA release without increasing TH RNA. Intrauterine growth retardation from chronic prenatal hypoxemia results in neonatal CA depletion and decreased CA responsiveness. We speculate that chronic hypoxia alters CA pathways, increasing the susceptibility of these infants to later stressors.

Expression of the rat preproenkephalin (ppENK) gene involves transsynaptic cholinergic mechanisms. We evaluated the effects of cholinergic agonist treatments in vivo on the expression of adrenomedullary ppENK RNA. Cholinergic treatment with nicotinic + muscarinic receptor agonists resulted in a synergistic 100-fold rise in steady-state ppENK messenger RNA levels, but only a 30- to 35-fold rise in initiation of steady-state ppENK RNA transcripts. The levels of initiated ppENK steady-state RNA peaked at two days, whereas mature (1.45 kb) ppENK mRNA levels continued to rise, peaking at four days. This suggested that other transcriptional (attenuation or alternative splicing) or post-transcriptional (RNA stabilization) regulatory mechanisms must be operative. As multiple ppENK RNA start sites exist, we examined how usage of multiple sites was altered by cholinergic treatments. The predominant start site changed from E2 in the basal state, to E4 after primary cholinergic stimulation, to E3 after re-treatment. This represents novel example of differential usage of multiple RNA initiation start sites in vivo. Differences in initiated and mature transcripts are consistent with at least four mechanisms involved in control of cholinergic-induced ppENK RNA expression: (i) simply new initiation of RNA transcripts, (ii) differential usage of the multiple RNA start sites, (iii) stabilization of mRNA transcripts, and (iv) attenuation and/or alternative RNA splicing of RNA transcripts.

The significance of the 5' heterogeneity of the transmitter gene ppEnk was evaluated by comparing start site usage (E1-E4) between 12 tissues from untreated rats, using primer extension analysis. In the basal state, we found that E3- and E4-initiated transcripts accounted for 80% of the total striatal RNA present compared with a preferential usage of the E2 start site in all other tissues. To determine whether this selective expression could be modified by biologically relevant pathways, rats were made hypoglycemic. After insulin shock, only E3 + E4-initiated transcripts increased (16-fold at 1 day) in the adrenal medulla but were unaffected in the striatum. As the effects of insulin shock on the adrenal medulla are mediated by cholinergic pathways and the striatum also receives cholinergic inputs, we also compared the effects of cholinergic drug treatments on start site usage in these two tissues. Rats were treated with cholinergic agonists (nicotine + oxotremorine) which induced adrenomedullary E2 and E3 + E4 transcripts (5- and 80-fold, respectively). This effect peaked at 2 days. In contrast, in the same animals, striatal ppEnk RNA (E3 + E4) increased only 10-15-fold after drug treatment. Hence it appears that biologically relevant whole animal stimuli (insulin shock or cholinergic agents) activate biochemical pathways, which affect start site usage in a tissue-specific fashion. Selective RNA start site usage suggests a biological significance, which may be important in the widespread tissue expression of this gene.

Fetal cardiovascular response to acute hypoxemia is characterized by bradycardia, hypertension, and redistribution of cardiac output. The role of aortic and carotid chemoreceptors in mediating these responses was examined in eight sinoaortic-denervated and nine shamoperated fetal lambs. Blood gases, pH, heart rate, arterial pressure, and blood flow distribution were determined before and during hypoxemia. In intact fetuses, heart rate fell from 184 +/- 12 to 165 +/- 23 beats/min (p less than 0.01) but increased from 184 +/- 22 to 200 +/- 16 beats/min (p less than 0.05) in the sinoaortic-denervated fetuses. Intact fetuses showed an early hypertensive response to hypoxemia, whereas the sinoaortic-denervated fetuses developed a delayed, progressive rise in blood pressure. In both groups, fetal cardiac output and umbilical blood flow were maintained; cerebral, myocardial, and adrenal blood flow increased, and pulmonary blood flow decreased. Peripheral blood flow decreased 39% (p less than 0.001) in intact fetuses but was maintained in sinoaortic-denervated fetuses. Vascular responses to hypoxia in the brain, heart, adrenal, and lungs are regulated primarily by direct local effects. During hypoxemia, peripheral chemoreceptors mediate bradycardia and peripheral vasoconstriction but do not appear to be crucial for immediate fetal survival.

A major control of gene expression occurs at the level of initiation of RNA transcription. In the nervous system this is reflected in part by 5' end RNA heterogeneity of neural transcripts. We now report the characterization of four preproenkephalin (ppEnk) RNA initiation sites in the rat brain striatum. In the adrenal medulla two ppEnk transcriptional start sites were detected. Moreover, cholinergic induction of ppEnk RNA initiation was observed in the adrenal medulla, but not in the striatum. The converse was true following handling stress. Our observations suggest that selective start site usage and stimulus evoked induction of specific RNA initiation is tissue-specific. We speculate that start site usage and induction may provide separate mechanisms through which neuronal gene expression is controlled in anatomically, as well as functionally distinct neurohumoral structures.

To assess the effect of various degrees of umbilical cord compression on fetal oxygenation, we instrumented fetal lambs at 120 to 128 days' gestation. An electromagnetic flow transducer was placed around the common umbilical artery to record umbilical blood flow flow continuously. Catheters were passed into an umbilical vein and a hind limb artery and vein, and a balloon occluder was placed around the umbilical cord. After recovery from operation, umbilical blood flow was reduced to 75%, 50%, and 25% of control values by controlled cord occlusion. Umbilical venous oxygen content did not change during cord compression; thus, oxygen delivery was linearly related to umbilical blood flow. Oxygen consumption of the fetus was maintained with reduction of umbilical blood flow to about 50% of control values; further reductions were associated with a progressive fall in fetal oxygen consumption. With reduced umbilical flow, there was a progressive increase in oxygen extraction from a control of 33.6% +/- 4.8% to 67.7% +/- 11.3% during 75% reduction of flow.

The effects of opiate receptor antagonism on the fetal cardiovascular response to hypoxemia were examined by means of the radionuclide-labeled microsphere technique. Heart rate, blood pressure, and cardiac output were measured during baseline periods, during hypoxemia, and before and after infusion of either naloxone (1 mg/kg) or an equivalent volume of 0.0% saline solution. Seventeen fetal sheep were subjected to maternal hypoxemia by allowing the ewes to breathe 10% oxygen (3% carbon dioxide, 87% nitrogen). The fetuses responded with bradycardia (p less than 0.002 compared with control), increased blood pressure (p less than 0.002 compared with control), and no significant change in combined ventricular output or placental blood flow. After naloxone, the bradycardia increased by 10% (p less than 0.001), and both combined ventricular output and placental blood flow fell by 20% (p less than 0.01 and p less than 0.01, respectively). The fetal bradycardic response to naloxone was reversible with atropine. In fetuses with normal oxygenation of the blood (normoxemic), naloxone had no significant effect on heart rate and blood pressure. These data indicate that endogenous opiates (e.g., endorphin and enkephalin) are important in regulating the fetal circulation during hypoxia, and that the effects of opiate receptor antagonism may be mediated through the autonomic nervous system.

In order to develop a simple in vitro method for assessing adequacy of placental perfusion, umbilical flow was measured in placentae from 10 normal control women and from 10 women with pre-eclampsia, by infusing through the umbilical arteries a heparinized 0.9% saline solution. The average induced umbilical flow in placentae from uneventful pregnancies was 276 +/- 16 SE ml/min compared with 163 +/- 12 ml/min (p less than 0.001) in the pre-eclamptic group. In angiographic studies, 79 +/- 2 SE% of the cotyledons from the normal series, and only 56 +/- 3% (p less than 0.001) from the pre-eclamptic series were functional. Additionally, gross and histological examination revealed three distinct types of cotyledon. Placental areas that blanched following saline infusion showed no blood in the collapsed villi or in the intervillous space; areas distinguished by a ruddy appearance following perfusion showed blood trapped in the villi and in the intervillous space; in a third area, the findings were mixed. When compared with placental zones identified by perfusion with 5% Hypaque solution, these three anatomical regions corresponded to normal, reduced, or absent flow (blanched, intermediate, or ruddy regions, respectively). We conclude that under the conditions of this in vitro study, pre-eclamptic placentae had a greater proportion of umbilical perfusion deficits than had normal placentae.

The cardiovascular and respiratory effects of the naturally occurring endogenous opiate, methionine-enkephalin, were studied in 23 fetal sheep, five newborn lambs, 15 pregnant sheep, and four nonpregnant ewes. The opiate peptide produced dose-dependent decreases in heart rate and blood pressure in fetal and neonatal lambs but increased heart rate and blood pressure followed immediately by decreased heart rate and blood pressure in pregnant ewes. The circulatory responses were examined by pharmacologic blockade of receptor activity and by vagotomy. The bradycardia and hypotension in the fetus and tachycardia and hypertension in the adult were shown to be mediated by autonomic efferent nerves. Sinoaortic denervation did not affect the fetal responses to infused enkephalin. Respiration decreased in fetal as well as postnatal animals even at doses of methionine-enkephalin that did not significantly affect heart rate and blood pressure. These data indicate that the cardiovascular effects of infused enkephalins undergo maturational changes and are mediated by the autonomic nervous system.

The use of molecular biological approaches has defined new mechanisms that store information in the mammalian nervous system. Environmental stimuli alter steady-state levels of messenger RNA species encoding neurotransmitters, thereby altering synaptic, neuronal, and network function over time. External or internal stimuli alter impulse activity, which alters membrane depolarization and selectively changes the expression of specific transmitter genes. These processes occur in diverse peripheral and central neurons, suggesting that information storage is widespread in the neuraxis. The temporal profile of any particular molecular mnemonic process is determined by specific kinetics of turnover and by the geometry of the neuron resulting in axonal transport of molecules to different synaptic arrays at different times. Generally, transmitters, the agents of millisecond-to-millisecond communication, are subject to relatively long-lasting changes in expression, ensuring that ongoing physiological function is translated into information storage.

Cell-mediated immunity is not well characterized in very low birth weight infants, and abnormalities may represent a significant vulnerability to infection. This report describes 165 serial studies in 58 infants between 700 and 1300 g birth weight during the first 8 wk of life. Two ml of blood were drawn at 2-wk intervals to measure T cell numbers and subsets and response to phytohemagglutinin (PHA). Overall, lymphocyte proliferation to PHA averaged 17,264 cpm, significantly less than the adult control (23,566 cpm). T cell numbers and subsets were CD3 62% (adult controls 75%), CD4 45% (49%), and CD8 18.6% (27%). Values at birth were lower as all parameters increased for at least the first 4 wk of life: PHA at birth was 15,464 cpm, CD3 48%, CD4 37%, and CD8 13%. Because of the lymphocytosis of premature infants, the absolute numbers of total T cells and subsets were within the normal adult range despite less than 50% of the mononuclear cells at birth being T cells. A study of five infants demonstrated an average of 52% B7+ cells at birth showing that the number of B cells at birth was increased approximately 10-fold over the control number in adults. Clinical correlation showed that the increases in both the % CD8 and the absolute number of CD8+ lymphocytes after birth were correlated with both the occurrence of sepsis and the assessed lymphocyte subsets in a sizeable number of very low birth weight infants serially during the first 8 wk of life including lymphocyte function using isolated mononuclear cells.(ABSTRACT TRUNCATED AT 250 WORDS)