Spatial Learning and Stress Response of Male Rats Prenatally Exposed to Dexamethasone

Dexamethasone is routinely administered to women at risk for a preterm birth in order to enhance fetal lung development and reduce uterine contractions. Research has demonstrated possible behavioral abnormalities in adulthood as a result of dexamethasone treatment. Using nonlinear mixed effects modeling, this study found thatprenatal dexamethasone treatment impaired spatial learning and memory of adult male Sprague-Dawley rats. Prenatal dexamethasone treatment also led to more anxiety related behaviors on Elevated Plus Maze testing 1.5 hours after a stress challenge. Because theassumptions underlying the independent samples t-test were violated, the randomization test was used to compare groups on the Elevated Plus Maze.

EFFECTS OF PRENATAL DEXAMETHASONE ON HIPOPCAMPAL SEROTONIN 1A RECEPTORS IN ADULT MALE RATS

The main activation route for the stress response is the hypothalamo-pituitaryadrenal axis (HPA) and the sympatho-adrenomedullary system. The HPA axis is a neuroendocrine feedback loop mediated by an array of tissue specific hormones, receptors and neurotransmitters that regulate glucocorticoid (GC) release. GCs are steroidal hormones produced by the adrenal glands and are key players in a negativefeedback loop controlling HPA activity. They influence the HPA axis through glucocorticoid receptors in the hypothalamus and pituitary and through both glucocorticoid (GR) and mineralcorticoid receptors (MR) that are co-localized in the hippocampus. Repeated or chronic stress exerts a negative influence on these HPA axis regulatory sites and contributes to potentially pathological conditions, especially during early development. For example, chronic stress promotes increased maternal adrenal gland secretion of glucocortiocoid, leading to abnormally high concentrations of GC inthe fetal environment. The timing and maturation of the HPA axis relative to birth is highly species specific and is closely linked to landmarks in fetal development. In rats this development of the HPA axis takes place in utero and continues even shortly after birth. It is likely that the maternal endocrine environment will affect fetal development during this critical time point and may alter the overall set point for the expression ofgenes and their protein products that mediate fetal HPA axis function. Dexamethasone (DEX) is a synthetic glucocorticoid (sGC) and is a consensus treatment in preterm pregnancies used to expedite fetal lung development. However it has been shown that DEX causes long term physiological and behavioral disorders in prenatally-exposed laboratory animals. Previous studies have also shown that it alters the MR: GR receptor ratio in the hippocampus. Taking into consideration corticosteroid regulation of serotonin receptors, especially 5HT1A receptors and their putative interaction with glucocorticoid receptors in the hippocampus, we hypothesized that prenatal DEX exposure would lead to changes in the expression and function of 5HT1A receptors in the hippocampus. We administered DEX to rat dams during the last trimester of gestation and investigated the changes in these receptors in the adult rat offspring. Radioligand receptor binding assays were used to study hippocampal 5HT1A receptor binding affinity and number. Our results demonstrate that hippocampal 5HT1A receptors are increased in the DEX animalscompared with controls by 36%, with no change in binding affinity. The efficiency of ligand-induced receptor signal transduction via G-protein activation was also studied using [35S]GTPγS incorporation assay. Using this technique, we showed that there was no significant difference in the maximum ligand mediated stimulation (Emax) of 5HT1Areceptors between control and dex exposed animals. However, the intracellular signalling efficiency of hippocampal 5HT1A receptors was diminished, since a significant increase in EC50 values was obtained with the dex exposed group showing a value 51% higherEC50 than controls. Taken together these data illustrate a considerable change in the 5HT1A component of the serotonergic system following prenatal DEX exposure.

Oral sucrose and "facilitated tucking" for repeated pain relief in preterms: a randomized controlled trial

To test the comparative effectiveness of 2 nonpharmacologic pain-relieving interventions administered alone or in combination across time for repeated heel sticks in preterm infants.

Vibrating Membrane Devices Deliver Aerosols More Efficient than Standard Devices: A Study in a Neonatal Upper Airway Model

Abstract Background: Aerosol therapy in preterm infants is challenging, as a very small proportion of the drug deposits in the lungs. Aim: Our aim was to compare efficiency of standard devices with newer, more efficient aerosol delivery devices. Methods: Using salbutamol as a drug marker, we studied two prototypes of the investigational eFlow(®) nebulizer for babies (PARI Pharma GmbH), a jet nebulizer (Intersurgical(®) Cirrus(®)), and a pressurized metered dose inhaler (pMDI; GSK) with a detergent-coated holding chamber (AeroChamber(®) MV) in the premature infant nose throat-model (PrINT-model) of a 32-week preterm infant (1,750 g). A filter or an impactor was placed below the infant model's "trachea" to capture the drug dose or particle size, respectively, that would have been deposited in the lung. Results: Lung dose (percentage of nominal dose) was 1.5%, 6.8%, and 18.0-20.6% for the jet nebulizer, pMDI-holding chamber, and investigational eFlow nebulizers, respectively (p<0.001). Jet nebulizer residue was 69.4% and 10.7-13.9% for the investigational eFlow nebulizers (p<0.001). Adding an elbow extension between the eFlow and the model significantly lowered lung dose (p<0.001). A breathing pattern with lower tidal volume decreased deposition in the PrINT-model and device residue (p<0.05), but did not decrease lung dose. Conclusions: In a model for infant aerosol inhalation, we confirmed low lung dose using jet nebulizers and pMDI-holding chambers, whereas newer, more specialized vibrating membrane devices, designed specifically for use in preterm infants, deliver up to 20 times more drug to the infant's lung.

[Childhood's determinants for high blood pressure in adulthood]

Hypertension has been estimated to affect 20 - 25% of the adult population and represents an important risk factor for cardiovascular disease like coronary heart disease, stroke and peripheral artery occlusive disease. In addition, hypertension supports the development and progression of chronic kidney insufficiency. The interaction of multiple genetic and environmental factors are felt to influence the level of blood pressure. Epidemiological data in the sixties and seventies demonstrated a correlation between cardiovascular disease and infant mortality in the same population. In the late eighties Barker and coworkers described a strong correlation between low birth weight and increased risk for the development of cardiovascular complications. It has been supposed that factors influencing the intrauterine growth and development can lead to adult cardiovascular diseases, known as the concept of "fetal programming". Beside the effect of fetal programming, multiple (preventable and non-preventable) factors determine the blood pressure level in childhood, which will define adult blood pressure level through the blood pressure tracking from childhood to adulthood. Hence, the prevention of cardiovascular disease in adulthood begins in childhood through identification of preventable risk factors as for example obesity and passive smoking and recognition of risk groups like small for gestational age or preterm children.

A proteome signature for intrauterine growth restriction derived from multifactorial analysis of mass spectrometry-based cord blood serum profiling

Intrauterine growth restriction (IUGR) is defined as a condition in which the fetus does not reach its genetically given growth potential, resulting in low birth weight. IUGR is an important cause of perinatal morbidity and mortality, thus contributing substantially to medically indicated preterm birth in order to prevent fetal death. We subjected umbilical cord blood serum samples either belonging to the IUGR group (n = 15) or to the control group (n = 15) to fractionation by affinity chromatography using a bead system with hydrophobic interaction capabilities. So prepared protein mixtures were analyzed by MALDI-TOF mass spectrometric profiling. The six best differentiating ion signals at m/z 8205, m/z 8766, m/z 13 945, m/z 15 129, m/z 15 308, and m/z 16 001 were collectively assigned as IUGR proteome signature. Separation confidence of our IUGR proteome signature reached a sensitivity of 0.87 and a specificity of 0.93. Assignment of ion signals in the mass spectra to specific proteins was substantiated by SDS-PAGE in conjunction with peptide mass fingerprint analysis of cord blood serum proteins. One constituent of this proteome signature, apolipoprotein C-III(0) , a derivative lacking glycosylation, has been found more abundant in the IUGR cord blood serum samples, irrespective of gestational age. Hence, we suggest apolipoprotein C-III(0) as potential key-marker of the here proposed IUGR proteome signature, as it is a very low-density lipoprotein (VLDL) and high-density lipoprotein (HDL) member and as such involved in triglyceride metabolism that itself is discussed as being of importance in IUGR pathogenesis. Our results indicate that subtle alterations in protein glycosylation need to be considered for improving our understanding of the pathomechanisms in IUGR.

Early assessment of brain maturation by MR imaging segmentation in neonates and premature infants

PURPOSE: We evaluated the impact of premature extrauterine life on brain maturation. PATIENTS AND METHODS: Twelve neonates underwent MR imaging at 40 (39.64 +/- 0.98) weeks (full term). Fifteen premature infants underwent 2 MR imaging examinations, after birth (preterm at birth) and at 40 weeks (41.03 +/- 1.33) (preterm at term). A 3D MR imaging technique was used to measure brain volumes compared with intracranial volume: total brain volume, cortical gray matter, myelinated white matter, unmyelinated white matter, basal ganglia (BG), and CSF. RESULTS: The average absolute volume of intracranial volume (269.8 mL +/- 36.5), total brain volume (246.5 +/- 32.3), cortical gray matter (85.53 mL +/- 22.23), unmyelinated white matter (142.4 mL +/-14.98), and myelinated white matter (6.099 mL +/-1.82) for preterm at birth was significantly lower compared with that for the preterm at term: the average global volume of intracranial volume (431.7 +/- 69.98), total brain volume (391 +/- 66,1), cortical gray matter (179 mL +/- 41.54), unmyelinated white matter (185.3 mL +/- 30.8), and myelinated white matter (10.66 mL +/- 3.05). It was also lower compared with that of full-term infants: intracranial volume (427.4 mL +/- 53.84), total brain volume (394 +/- 49.22), cortical gray matter (181.4 +/- 29.27), unmyelinated white matter (183.4 +/- 27.37), and myelinated white matter (10.72 +/- 4.63). The relative volume of cortical gray matter (30.62 +/- 5.13) and of unmyelinated white matter (53.15 +/- 4.8) for preterm at birth was significantly different compared with the relative volume of cortical gray matter (41.05 +/- 5.44) and of unmyelinated white matter (43.22 +/- 5.11) for the preterm at term. Premature infants had similar brain tissue volumes at 40 weeks to full-term infants. CONCLUSION: MR segmentation techniques demonstrate that cortical neonatal maturation in moderately premature infants at term and term-born infants was similar.

Lung-function tests in neonates and infants with chronic lung disease: tidal breathing and respiratory control

This paper is the fourth in a series of reviews that will summarize available data and critically discuss the potential role of lung-function testing in infants with acute neonatal respiratory disorders and chronic lung disease of infancy. The current paper addresses information derived from tidal breathing measurements within the framework outlined in the introductory paper of this series, with particular reference to how these measurements inform on control of breathing. Infants with acute and chronic respiratory illness demonstrate differences in tidal breathing and its control that are of clinical consequence and can be measured objectively. The increased incidence of significant apnea in preterm infants and infants with chronic lung disease, together with the reportedly increased risk of sudden unexplained death within the latter group, suggests that control of breathing is affected by both maturation and disease. Clinical observations are supported by formal comparison of tidal breathing parameters and control of breathing indices in the research setting.

Fetal thymic involution: a sonographic marker of the fetal inflammatory response syndrome

OBJECTIVE: The purpose of this study was to evaluate whether there is a relationship between the sonographic fetal thymus size and the presence of an intrauterine infection in patients with preterm labor. STUDY DESIGN: Thirty-one women who had been admitted with preterm labor and intact membranes between 24 and 32 weeks of gestation were included. Fetal thymus perimeter was measured sonographically, and amniocentesis for the microbiologic assessment of the amniotic cavity was performed. Placentas and umbilical cords were examined for the presence of chorioamnionitis/funisitis. RESULTS: The prevalence of preterm delivery and intra-amniotic infection was 51.6% (16/31 women) and 32.3% (10/31 women), respectively. In all cases with intrauterine infection and in 23.8% of cases without intrauterine infection, the fetal thymus perimeter was below the 5th percentile for gestational age (10/10 women vs 5/21 women; P < .01). Isolated histologic chorioamnionitis and funisitis were found in 22.6% and 25.8% of fetuses, respectively. The fetal thymus was below the 5th percentile for gestational age in 100%, 71.4%, and 12.5% of patients with histologic signs of funisitis and isolated chorioamnionitis and without histologic signs of infection, respectively. CONCLUSION: Fetal thymus involution in preterm labor patients is strongly associated with funisitis, which is the histologic manifestation of the fetal inflammatory response syndrome.

Effects of lamotrigine alone and in combination with MK-801, phenobarbital, or phenytoin on cell death in the neonatal rat brain

The neonatal rat brain is vulnerable to neuronal apoptosis induced by antiepileptic drugs (AEDs), especially when given in combination. This study evaluated lamotrigine alone or in combination with phenobarbital, phenytoin, or the glutamate antagonist (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate (MK-801) for a proapoptotic action in the developing rat brain. Cell death was assessed in brain regions (striatum, thalamus, and cortical areas) of rat pups (postnatal day 8) by terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay, 24 h after acute drug treatment. Lamotrigine alone did not increase neuronal apoptosis when given in doses up to 50 mg/kg; a significant increase in cell death occurred after 100 mg/kg. Combination of 20 mg/kg lamotrigine with 0.5 mg/kg MK-801 or 75 mg/kg phenobarbital resulted in a significant increase in TUNEL-positive cells, compared with MK-801 or phenobarbital treatment alone. A similar enhancement of phenytoin-induced cell death occurred after 30 mg/kg lamotrigine. In contrast, 20 mg/kg lamotrigine significantly attenuated phenytoin-induced cell death. Lamotrigine at 10 mg/kg was without effect on apoptosis induced by phenytoin. Although the functional and clinical implications of AED-induced developmental neuronal apoptosis remain to be elucidated, our finding that lamotrigine alone is devoid of this effect makes this drug attractive as monotherapy for the treatment of women during pregnancy, and for preterm or neonatal infants. However, because AEDs are often introduced as add-on medication, careful selection of drug combinations and doses may be required to avoid developmental neurotoxicity when lamotrigine is used in polytherapy.

Respiratory syncytial virus infection in 406 hospitalized premature infants: results from a prospective German multicentre database

Premature birth, chronic lung disease of prematurity (CLD), congenital heart disease and immunodeficiency predispose to a higher morbidity and mortality in respiratory syncytial virus (RSV) infection. This study describes the preterms hospitalised with RSV infection from the prospective German DSM RSV Paed database. The DMS RSV Paed database was designed for the prospective multicentre documentation and analysis of clinically relevant aspects of the management of inpatients with RSV infection. This study covers six consecutive RSV seasons (1999-2005); the surveillance took place in 14 paediatric hospitals in Germany. Of the 1,568 prospectively documented RSV infections, 26% (n=406) were observed in preterms [vs. 1,162 children born at term (74%)] and 3% (n=50) had CLD, of which 49 had received treatment in the last 6 months ('CLDplus'). A significantly higher proportion in the preterm group had congenital heart disease, nosocomial infection, and neuromuscular impairment. There were significantly more children older than 24 months in the preterm group. The attributable mortality was 0.2% (n=2) in children born at term vs. 1.2% (n=5) in the preterm group (p=0.015) [preterm plus CLD 8.0% (n=4 of 50); McIntosh grade 1, 8.6% (n=3 of 35) and McIntosh Grade 4, 15% (n=3 of 20)]. Eight patients were categorized as 'palivizumab failures'. In the multivariate analysis, premature birth, CLD(plus), and nosocomial infection were significantly and independently associated with the combined outcome 'complicated course of disease'. In conclusion, this is the first prospective multicentre study from Germany that confirms the increased risk for severe RSV disease in preterms, in particular in those with CLD treated in the last 6 months before the onset of the infection. From the perspective of our results, the statements of the German Society of Paediatric Infectious Diseases considering the use of passive immunisation (2003) seem reasonable.

Nanoduct(R) sweat testing for rapid diagnosis in newborns, infants and children with cystic fibrosis

Determination of chloride concentration in sweat is the current diagnostic gold standard for Cystic Fibrosis (CF). Nanoduct(R) is a new analyzing system measuring conductivity which requires only 3 microliters of sweat and gives results within 30 minutes. The aim of the study was to evaluate the applicability of this system in a clinical setting of three children's hospitals and borderline results were compared with sweat chloride concentration. Over 3 years, 1,041 subjects were tested and in 946 diagnostic results were obtained. In 95 children, Nanoduct(R) failed (9.1% failure rate), mainly due to failures in preterm babies and newborns. Assuming 59 mmol/L as an upper limit of normal conductivity, all our 46 CF patients were correctly diagnosed (sensitivity 100%, 95% CI: 93.1-100; negative predicted value 100% (95% CI: 99.6-100) and only 39 non CF's were false positive (39/900, 4.3%; specificity 95.7%, 95%CI: 94.2-96.9, positive predicted value 54.1% with a 95%CI: 43.4-65.0). Increasing the diagnostic limit to 80 mmol/L, the rate fell to 0.3% (3/900). CF patients had a median conductivity of 115 mmol/L; the non-CF a median of 37 mmol/L. In conclusion, the Nanoduct(R) test is a reliable diagnostic tool for CF diagnosis: It has a failure rate comparable to other sweat tests and can be used as a simple bedside test for fast and reliable exclusion, diagnosis or suspicion of CF. In cases with borderline conductivity (60-80 mmol/L) other additional methods (determination of chloride and genotyping) are indicated.

Pain management and the effect of guidelines in neonatal units in Austria, Germany and Switzerland

BACKGROUND: Painful invasive procedures are frequently performed on preterm infants admitted to a neonatal intensive care unit (NICU). The aim of the present study was to investigate current pain management in Austrian, German and Swiss NICU and to identify factors associated with improved pain management in preterm infants. METHODS: A questionnaire was sent to all Austrian, German and Swiss pediatric hospitals with an NICU (n = 370). Pain assessment and documentation, use of analgesics for 13 painful procedures, presence of written guidelines for pain management and the use of 12 analgesics and sedatives were examined. RESULTS: A total of 225 units responded (61%). Pain assessment and documentation and frequent analgesic therapy for painful procedures were performed more often in units using written guidelines for pain management and in those treating >50 preterm infants at <32 weeks of gestation per year. This was also the case for the use of opioid analgesics and sucrose solution. Non-opioid analgesics were used more often in smaller units and in units with written guidelines. There was a broad variation in dosage of analgesics and sedatives within all groups. CONCLUSION: Pain assessment, documentation of pain and analgesic therapy are more frequently performed in NICU with written guidelines for pain management and in larger units with more than 50 preterm infants at <32 weeks of gestation per year.

Perinatal adaptation in mammals: the impact of metabolic rate

Mammalian birth is accompanied by profound changes in metabolic rate that can be described in terms of body size relationship (Kleiber's rule). Whereas the fetus, probably as an adaptation to the low intrauterine pO2, exhibits an "inappropriately" low, adult-like specific metabolic rate, the term neonate undergoes a rapid metabolic increase up to the level to be expected from body size. A similar, albeit slowed, "switching-on" of metabolic size allometry is found in human preterm neonates whereas animals that are normally born in a very immature state are able to retard or even suppress the postnatal metabolic increase in favor of weight gain and O2 supply. Moreover, small immature mammalian neonates exhibit a temporary oxyconforming behavior which enhances their hypoxia tolerance, yet is lost to the extent by which the size-adjusted metabolic rate is "locked" by increasing mitochondrial density. Beyond the perinatal period, there are no other deviations from metabolic size allometry among mammals except in hibernation where the temporary "switching-off" of Kleiber's rule is accompanied by a deep reduction in tissue pO2. This gives support to the hypothesis that the postnatal metabolic increase represents an "escape from oxygen" similar to the evolutionary roots of mitochondrial respiration, and that the overall increase in specific metabolic rate with decreasing size might contribute to prevent tissues from O2 toxicity.

[Infections in pregnancy]

Infections in pregnancy may complicate its course and harm the fetus or newborn after vertical transmission. Treatment of asymptomatic bacteriuria is mandatory in pregnant women given the high risk of secondary pyelonephritis. Intraamniotic infection usually arises by the ascending route and is associated with premature rupture of membranes. Vaginal infections promote preterm labour or premature rupture of membranes and may be transmitted to the child during labour. They must therefore be treated although they often cause little discomfort to the pregnant woman. Systemic infections due to viral, protozoal and bacterial pathogens may be transmitted transplacentally and cause embryopathies, fetopathies or neonatal infections. Depending on the responsible agent the negative impact on the course of pregnancy and on the fetus' or neonate's health can be prevented or reduced by prophylactic or therapeutic interventions.