bluuebunny/crossref_metadata_2025 huggingface dataset:
Maturation of Brain Stem Neurons Involved in Respiratory Rhythmogenesis: Biochemical, Bioelectrical and Morphological Properties
Authors: Denavit-Saubié M. , Kalia M. , Pierrefiche O. , Schweitzer P. , Foutz A.S. , Champagnat J.
Published: October 2009

Neonatal and adult respiratory-related functions of brain stem were compared using in vivo or in vitro approaches. The control of inspiratory off-switch by glutamate-like neurotransmitters was found active at birth. However, neurons from the nucleus tractus solitarius (NTS) are immature at birth because they present growth cones and the transient potassium current appears progressively during the first week of life in association with modification of the dendritic tree. These data support the hypothesis that the mechanisms of respiratory rhythmogenesis are different at birth and in the adult.
Possible Involvement of Serotonin in Obstructive Apnea of the Newborn
Authors: Morin D. , Di Pasquale E. , Hilaire G. , Monteau R.
Published: October 2009

Experiments were conducted on newborn rats in order to study the serotonergic modulation of the central respiratory activity during the neonatal period. In vitro experiments performed on isolated brainstem spinal cord preparations demonstrated that serotonin exerts a permanent excitatory modulation on the central respiratory rhythm generator but depresses the inspiratory motor output to the genioglossus muscle. In vivo experiments confirmed that increasing endogenous serotonin levels decreases the inspiratory activity of the genioglossus and elicits drastic obstructive apneas.
Maturation of Fetal Breathing Activity
Authors: Blanco Carlos E.
Published: October 2009

Spontaneous breathing movements are present during fetal life and they are important for normal development of the lung. Early in gestation they seem to represent free-running activity of the respiratory centers, not controlled by peripheral mechanisms but probably dependent on a tonic CO2 drive. Maturation of sleep states brings into play powerful brainstem inhibitory mechanisms which control FBM. At birth these mechanisms must be overridden to allow the establishment of continuous breathing.
A Perspective on Neuropathologic Findings in Victims of the Sudden Infant Death Syndrome: The Triple-Risk Model
Authors: Filiano James J. , Kinney Hannah C.
Published: October 2009

Neuropathologic studies in SIDS victims support the concept that they are not entirely ‘normal’ prior to death, but rather possess underlying vulnerabilities which put them at risk for sudden death. This concept forms a key link in a triple-risk model for the pathogenesis of SIDS proposed by us. According to this model, sudden death in SIDS results from the intersection of three overlapping factors: (1) a vulnerable infant; (2) a critical developmental period in homeostatic control, and (3) an exogenous stressor(s). An infant will die of SIDS only if he/she possesses all three factors; the infant’s vulnerability lies latent until he/she enters the critical period and is subject to an exogenous stressor. According to this model, heterogeneous disorders may make the infant vulnerable to sudden death during the critical period, as potentially exemplified by two previously reported lesions in SIDS brains (arcuate nucleus hypoplasia and subtle hypomyelination). Nevertheless, the triple-risk model does not preclude the possibility that the majority of SIDS deaths will be explained by a single common pathway upon which multiple stressors impinge to produce sudden death during the critical period.
Ventilatory Strategy in Hypoxic or Hypercapnic Newborns
Authors: Bonora M. , Boule M. , Gautier H.
Published: October 2009

In conscious newborns, the ventilatory response to hypoxia is characterized by precocious hyperventilation followed by tardive hypoventilation, the latter disappearing with age. The hypoventilation could be mainly related to a weak peripheral drive and to the persistence of the diaphragmatic activity during expiration. Also, a decrease in metabolic rate and body temperature interferes with the response. The hyperventilation in response to hypercapnia increases as maturation proceeds and the maturation of the peripheral chemoreceptors contribute to this effect, as during hypoxia. The responses to both stimuli depend on many factors such as sleep state, anesthesia or ambient temperature.
Epidemiology and Pathophysiology of Apnoea of Prematurity
Authors: Poets Christian F. , Samuels Martin P. , Southall David P.
Published: October 2009

In preterm infants, reliance on the detection of apnoeic pauses and/or bradycardia results in significant amounts of hypoxaemia remaining undetected. In addition, recordings of breathing movements and ECG do not have predictive value for subsequent sudden infant death. In recent years, the ability to continuously monitor and record arterial oxygen saturation (SaO2) has produced important information regarding the mechanisms for respiratory events in the preterm population. Normal data on SaO2 (Nellcor N-200) and breathing movements have been collected in 160 preterm infants. Median baseline SaO2 during regular breathing was 99.5% (range 88.7-100) at the time of discharge from SCBU and 100% (95.3–100) at follow-up 6 weeks later. Episodic desaturations (SaO2 < 80% for ≥4s) ranged between 0 and 355 episodes per 12-hour recording. In a study of a separate group of 16 preterm infants with recurrent cyanotic episodes of unknown cause, the total number of abnormal hypoxaemic episodes was markedly increased. These hypoxaemic episodes were associated with three breathing pattern: (i) absent breathing movements; (ii) continued breathing movements, but absent airflow, and (iii) continuous airflow and breathing movements. Thus, preterm infants with cyanotic episodes have an increased number of clinically unapparent hypoxaemic episodes, some of which occur with continued breathing and airflow. In another study of 79 patients who had been born preterm and had a history of an apparent life-threatening event, 43 (54%) had abnormal oxygenation on multichannel recordings, including 23% with clinically undetected baseline hypoxaemia. Continuous additional inspired oxygen was given to 27 patients with recorded abnormalities in oxygenation and a history of recurrent ALTE needing cardiopulmonary resuscitation: in 25, episodes stopped or markedly reduced in frequency. Home PO2 monitoring has been undertaken in 73 patients for a median duration of 7.1 months. Recognition and treatment of abnormalities in episodic or baseline hypoxaemia may reduce the risk for recurrent cyanotic episodes or subsequent apparent life-threatening events at home. In infants with a history of such episodes, the use of additional inspired oxygen and home PO2 monitoring are helpful in management. The finding of abnormal hypoxaemia may be relevant to the increased risk of sudden death found in preterm infants.
Cerebral Blood Flow and Metabolism during Repeated Asphyxias in Newborn Piglets: Influence of Theophylline
Authors: Goplerud Jan M. , Delivoria-Papadopoulos Maria
Published: October 2009

The effect of theophylline on cerebral blood flow (CBF), oxygen transport, and energy metabolism was investigated during and following brief episodes of asphyxia. CBF was determined by microspheres during control, asphyxia, and recovery with reventilation after a single asphyxia (recovery I) and after 7 repeated asphyxias (recovery II). In addition, cerebral energy metabolism by 31P NMR spectroscopy and cerebral oxygen consumption (CMRO2) in newborn piglets treated with 30 mg/kg theophylline (serum levels 22-25 μg/ml) were compared with nontreated piglets. Theophylline increased CMRO2 during recovery I (348 μmol O2/min/100 g vs. 144 for non-theophylline) but not during control, asphyxia, or recovery II. There was no significant difference between the theophylline and non-theophylline groups in depletion of phosphoenergetics as measured by 31P NMR.
Apnea and Sleep State in Newborns and Infants
Authors: Gaultier Cl.
Published: October 2009

Many studies have shown a greater frequency of apneas in active sleep than in quiet sleep in healthy newborns and infants, both full-term and preterm. The ontogeny of increased apnea during active sleep is related to phasic inhibitory-excitatory central mechanisms occurring during active sleep. Respiratory instability in active sleep can be increased by factors which modify the newborn’s or infant’s homeostasis. We have shown: (1) an increase in body temperature (0.8 °C) significantly augments periodic breathing in preterm infants at 40 weeks postconceptional age; (2) maternal administration of meperidine is followed by a significant increase in number of apneas during the first hours of life in full-term newborns, but only during active sleep; (3) sleep deprivation induces significantly more obstructive respiratory events in active sleep than in quiet sleep in infants. Active sleep appears to be a risk period for exaggeration of the occurrence of apneas when the newborn’s or infant’s homeostasis is disturbed.
Cardiac and Respiratory Reactivity to Gastroesophageal Reflux: Experimental Data in Infants
Authors: Ramet J.
Published: October 2009

Gastroesophageal reflux associated with apnea and/or bradycardia induces both dilatation of the esophagus and abrupt intrusion of acid content in it. To evaluate the relative importance of these two types of stimulation on cardiac and respiratory responses, a series of experimental protocols were designed, in which we evaluated the influence of esophageal dilatation alone, acid infusion alone and both stimulations simultaneously. The passage of a volume in the lower third of the esophagus (n = 14) during reflux was simulated by balloon dilatation; the passage of acid gastric juice during reflux was simulated by an esophageal acid infusion test, within the physiological range (n = 8; duration = 5 min; pH = 2.2). Cardiac, respiratory and arousal responses were compared during a control period and during the distal balloon dilatation and esophageal saline and acid infusion periods. Distal esophageal balloon dilatation and acid infusion induced significant prolongation of the RR interval and of the duration of the respiratory cycle. The presence of the esophageal catheter did not lead to continuous vagal stimulation. Simultaneous stimulation by balloon dilatation and acid infusion provoked cardiac responses that were above the level reached by each stimulation separately. Behavioral and electroence-phalographic observations demonstrate significantly more frequent and longer arousal responses during the acid infusion than during control and saline infusion periods. We conclude that distal esophageal balloon dilatation and acid infusion elicit significant cardiac and respiratory responses in newborns during active sleep. Since arousal from sleep has been shown to facilitate esophageal clearance, we speculate that arousal responses, observed only during acid infusion, may be one of the defence mechanisms related to acid gastroesophageal reflux.
Modifications of Ventilatory Reflexes: An Efficient Therapy for Apneas of Prematurity?
Authors: Monin Pierre
Published: October 2009

The treatment of apneas of prematurity mainly involves the use of drugs (methylxanthines, doxapram). Despite evidence of the efficacy, some adverse effects may occur raising the question of other therapies. This brief review analyses the usefulness of methods influencing the ventilatory reflexes: cutaneous and proprioceptive stimulation and nasal continuous positive airways pressure proposed previously.
Value of Examination of the Gastric Aspirate for the Diagnosis of Neonatal Infection
Authors: Borderon E. , Desroches A. , Tescher M. , Bondeux D. , Chillou C. , Borderon J.C.
Published: October 2009

To evaluate the interest of examination of the gastric aspirate (GA) as a contribution to decision making of initial antimicrobial therapy, all 3,989 neonates delivered in Orléans Maternity Hospital in 1990 have been studied. Microscopic examination: polymorphonuclear leukocytes (PMN) were, respectively, absent/present/abundant in 180/130/25 treated (T) and in 2,567/1,032/90 untreated (NT) newboms. PMN were demonstrated in 2/5 documented, 4/6 obvious, 2/2 suspected and 34/ 58 possible infections. Bacteria were, respectively, absent/ present/abundant in 201/109/46 T newboms and in 2,722/ 877/56 NT newboms. Bacteria were demonstrated in 3/5 documented, 4/6 obvious, 2/2 suspected and 32/58 possible infections. Culture: the number of initially T and NT newboms was, respectively, for each bacterial species: Enterobacteriaceae 33/294, streptococci B (GBS), D and α-hemolytic 60/107, 12/110 and 18/70, Streptococcus pneumoniae 2/2, anaerobes 12/402, Listeria 3/0, Haemophilus species 4/4, Staphylococcus aureus 5/7, coagulase-negative staphylococci 25/1335, Lactobacillus 14/345, corynebacteria 10/196. In the 5 newboms with documented early onset meningitis and/or septicemia, 3 grew with GBS, Escherichia coli and Listeria. In the 4 newboms (2 meningitis and 2 urinary tract infections) with lateonset infection, no positive GA could be demonstrated. Although microscopic examination and cultures were statistically more frequently positive in T newboms, with variations dependent on the species of bacteria, more newboms without infection were colonized whatever the bacteria. Thus, bacteriological results of GA, if considered out of the clinical context, cannot be an argument for treatment.
Cerebral Blood Flow Autoregulation after Moderate Hypoxemia in the Newborn Piglet
Authors: Odden Jan-Petter , Farstad Teresa , Roll Ellen B. , Hall Christian , Bratlid Dag
Published: October 2009

The isotope-labelled microsphere method was used to study blood flow autoregulation in the brainstem (BS), cerebellum (CBL), cerebrum (CBR) and choroid plexus (ChPl) in 21 newborn piglets exposed to hypoxemia and/or hypovolemia. One group of piglets (n = 7) was made hypoxemic by breathing 10% O2 for 10 min, a second group (n = 8) was studied during hypoxemia (10% O2, 10 min), followed by hypovolemia (bleeding 20% of estimated blood volume). A third group of piglets (n = 6) was made hypovolemic by bleeding 20%. Hypoxemia significantly impaired the autoregulatory capacity in CBL and CBR resulting in a pressure-passive flow pattern. Hypovolemia alone did not produce any significant cerebral vascular response in BS, CBL and CBR, not even when hypovolemia was preceded by hypoxemia, indicating a rapid restoration of the autoregulatory capacity of the cerebral vasculature after hypoxemia of moderate duration. The hypotension seen both during hypoxemia and hypovolemia was gradually compensated for and normalized within 60 min. However, animals exposed to both hypoxemia and hypovolemia were still hypotensive 60 min after the hypoxemic insult. Cardiac output (CO) was not affected by hypoxemia, but was consistently reduced in hypovolemia. We therefore speculate that in the newborn a reduced CO might be a more specific parameter for hypovolemia than a low blood pressure.
Adrenocortical Stimulation of Stomach Development in the Prenatal Pig
Authors: Sangild Per T. , Silver Marian , Fowden Abigail L. , Turvey Alan , Foltmann Bent
Published: October 2009

Development of the porcine gastric proteases (chymosin, pepsin A, B and C) has been studied in the fetal pig in the last third of gestation (term 115 days). The possibility that the prepartum rise in circulating cortisol is involved in gastric maturation was investigated by infusing immature fetuses with cortisol (osmotic minipumps implanted at 82-90 days of gestation). Concentrations of prochymosin in fundic tissue and stomach contents increased before term, correlated positively with logio plasma cortisol values (r = 0.68-0.76, p < 0.001), and were stimulated by cortisol infusion (p < 0.001). The pH of stomach contents decreased (from pH 7 to 3), correlated negatively with logio plasma cortisol values (r = -0.69, p < 0.001), and was reduced by cortisol infusion (p < 0.05). Only trace amounts of pepsinogens could be detected in fetal pigs. By immunohistochemistry, it was shown that cortisol increased the number and distribution of prochymosin-containing cells in the fundic gland. Stimulating effects were also observed for the small populations of pepsinogen-reactive cells present in some of the fetal pigs. The results suggest that endogenous cortisol stimulates the rise in prochymosin synthesis and secretion together with increased gastric acidity in the prenatal period of the pig.
Effect of Blood Volume Expansion on Basal Plasma Atrial Natriuretic Factor and Adrenocorticotropic Hormone Secretions in the Fetal Rat at Term
Authors: Deloof S. , Chatelain A.
Published: October 2009

The effect of a blood volume expansion (1–1.5% of body weight) on atrial natriuretic factor (ANF) and adrenocorticotropic hormone (ACTH) secretions were investigated in 21-day-old rat fetuses injected intravenously through the umbilical vein with 50 μl of isotonic saline. Basal ANF and ACTH concentrations were determined in the plasma with specific radioimmunoassays over a 30-min observation period. The basal plasma ANF concentration increased rapidly 1 min after blood volume expansion and then decreased to the control value 5 min later. The basal plasma ACTH concentration decreased during the first 10 min after injection and then increased to the control value 30 min after intravascular volume load. The results suggest that the fetal rat in late gestation is able to respond to blood volume expansion by increasing ANF secretion.
Effects of Phenobarbital on Cerebral Blood Flow during Hypoxia
Authors: Cortey Anne , Monin Pierre , Hascoet Jean-Michel , Hamon Isabelle , Vert Paul
Published: October 2009

Phenobarbital (PB), at anticonvulsant dosages, has been used in an attempt to reduce hypoxic brain injury in asphyxiated newborn infants. The effects of PB pretreatment on the cerebral blood flow (CBF) response in hypoxia were studied in 15 curarized and mechanically ventilated piglets: 7 animals were pretreated with 20 mg/kg of PB (group 1) and 8 served as untreated controls (group 2). Successive aliquots (25 ml) of carbon monoxide were introduced into a closed ventilator circuit and CBF (measured with radiolabelled microspheres), arterial blood pressure, blood gases, arterial pH and PaO2 were subsequently determined at different levels of hypoxia. The amount of hemoglobin available for oxygen transport (i.e. total Hb – HbCO) was used to express hypoxic aggression and decreased from grade I (> 2 mmol/l) to grade II (1-2 mmol/l) to grade III (< 1 mmol/l). In the control group, CBF increased during grade-I hypoxia and continuously remained above baseline values during grade-II and grade-II hypoxia. In pretreated animals, however, only grade-II hypoxia was associated with a significant increase in CBF above baseline. In addition during grade-Ill hypoxia, CBF decreased to the prehypoxic values despite a fall in cerebral oxygen delivery and cardiac index. These data suggest that PB should be used with caution to prevent brain damage in the asphyxiated newborn infants.
Influence of Dexamethasone on Lymphocyte Proliferation in Whole Blood Cultures of Neonates
Authors: Schwarze J. , Bartmann P.
Published: October 2009

The lymphocyte proliferative response to mitogen stimulation was measured in cord blood cultures of term and preterm neonates. The lymphocyte proliferative response increased 150-to 400-fold above baseline after stimulation with mitogens. Dexamethasone suppressed the lymphocyte proliferative response in a concentration-dependent manner with considerable suppression at concentrations applied during treatment of preterm neonates for bronchopulmonary dysplasia (BPD). Dexamethasone and other corticosteroids tested in equipotent glucocorticoid concentrations suppressed the lymphocyte proliferative response to the same extent. We conclude that dexamethasone treatment for BPD may well compromise immune functions of preterm neonates.
Human Milk Banking: Influence of Storage Processes and of Bacterial Contamination on Some Milk Constituents
Authors: Pardou A. , Serruys E. , Mascart-Lemone F. , Dramaix M. , Vis H.L.
Published: October 2009

This paper reviews the effects of storage and bacterial content contaminating human milk on some milk constituents. Moreover, it reviews the inhibitory effect of refrigeration and freezing on bacterial growth. Our results suggest that the type and length of storage have an effect on some milk constituents, that this effect is modulated by the bacterial contamination of the milk and that refrigeration has a significant inhibitory effect on bacterial growth which is not observed after freezing. This stresses the importance of collecting noncontaminated milk and justifies the choice of refrigeration at 0-4°C for storage up to 8 days.
Is the Piglet a Useful Animal Model of Sudden Infant Death Syndrome?
Authors: Lavoue S. , Dagorne M. , Morvan H. , Madec F. , Durigon M.
Published: October 2009

A prospective study of early death was conducted in a large population of piglets in order to investigate the causes of mortality and determine whether this species could be useful as an animal model of the sudden infant death syndrome (SIDS). 1,921 live-born piglets were closely monitored from birth to 2 months of age. The cause of death was analyzed in all the animals which died during this period. Complete histological, bacteriological and virological examinations of all sudden death animals were compared to identical examinations performed in age-matched control animals. 384 animals (20%) died during the study period and 8 sudden deaths were observed (0.4%). The principal causes of nonsudden death were overlaying (9.4%), hypotrophy (6%), infection (2%) and acute fetal suffering (1.4%). Bacterial infection was found in 6 of the sudden deaths. There was 1 case of suffocation and 1 unexplained sudden death. Compared to controls, there was a significantly greater prevalence of pathology (p < 0.01) and of positive tissue bacteriology (p < 0.05) in sudden death animals. The 6 sudden deaths due to bacterial infections were clearly different from the human syndrome. Suffocation is a known cause of sudden infant death. In the final analysis, only 1 animal (0.5 %o) had an outcome which could be assimilated with SIDS. It is concluded that although there probably exists a syndrome in the piglet equivalent to SIDS, its incidence is very low and major obstacles related to the high level of early mortality in this species hinder investigation.
A Comparative Study of Hepatic HMG CoA Reductase Activity and LDL Receptor Relative Mass in Suckling and Adult Guinea Pigs
Authors: Hamilton Jennifer J. , Auestad Nancy , Innis Sheila M.
Published: October 2009

The reason why plasma cholesterol levels increase soon after birth is unknown but may be related to change rates of cholesterol synthesis and/or expression of LDL receptors. Plasma cholesterol levels, along with hepatic HMG CoA reductase activity, the rate-limiting enzyme of cholesterol synthesis, and hepatic LDL receptor relative mass were measured in suckling (1,4 and 8 days of age) and adult guinea pigs. Plasma cholesterol was measured by an enzymatic assay, HMG CoA reductase activity was determined using a radiolabelled substrate and LDL receptor-relative mass was measured by ligand blotting with gold-labelled rabbit βVLDL. Among the young animals, HMG CoA reductase activity and plasma cholesterol levels increased between 1 and 4 days of age. The LDL receptor mass did not change in the first 8 days after birth, but was 2-fold higher in adult than suckling animals. Hepatic HMG CoA reductase activity was also higher in the adult animals. Increased hepatic HMG CoA reductase and low LDL receptor mass may contribute to the elevation in plasma LDL cholesterol levels in the 4-day-old guinea pig.
Effects of Corticotropin-Releasing Factor, Arginine Vasopressin and Oxytocin on the Polymorphism of Plasma Adrenocorticotropic Hormone in the Rat Fetus in Late Pregnancy
Authors: Deloof S. , Chatelain A. , Leprêtre A.
Published: October 2009

The effects of rat corticotropin-releasing factor (rCRF, 1.25 pmol/50 μl/fetus), arginine vasopressin (AVP, 5 pmol/50 μl/fetus) and oxytocin (OT, 12.5 pmol/50 μl/fetus) alone or in association were investigated in 21-day-old rat fetuses injected intravenously through the umbilical vein. Blood samples were collected 15 and 30 min after injection for the determination of corticosterone concentration and the different plasma molecular adrenocorticotropic hormone (ACTH) forms isolated by chromatography on Sephadex G50 fine. All the plasma samples chromatographed 15 and 30 min after injection of the different peptides showed 3 different molecular ACTH forms: big ACTH ( > 20,000 molecular weight), intermediate ACTH (=13,000) and little ACTH (= 4,500). The injection of rCRF or AVP alone and rCRF in association with AVP or OT increased the concentrations of big ACTH 15 min and little ACTH 30 min after injection. The injection of OT alone or in association with AVP did not change the concentration of the 3 molecular ACTH forms 15 and 30 min after injection. The rise of big ACTH 15 min after injection was not associated with a significant increase in plasma corticosterone concentration, whereas the increase in little ACTH 30 min later enhanced plasma corticosterone concentration. Our results suggest that rCRF or AVP alone and rCRF in association with AVP or OT injected intravenously in the fetal rat produced a selective release of the molecular ACTH forms and the increase in the plasma corticosterone concentration occurred when the proportion of little ACTH which is the predominant ACTH form in the fetal rat was enhanced.
Development of Morphine Glucuronidation in Premature Neonates
Authors: Hartley Ronald , Green Martine , Quinn Michael W. , Rushforth Alison , Levene Malcolm I.
Published: October 2009

In premature neonates (25–34 weeks gestation) who were given morphine intravenously during the first 24 h of life, only morphine, and morphine-3-glucuronide (M3G) were detected in plasma obtained after a 2-hour loading infusion, but morphine-6-glucuronide (M6G) could also be quantified following 24 h of continuous infusion. M3G/morphine and M6G/morphine plasma concentration ratios increased significantly with increasing birth weight. However, the M6G/M3G plasma concentration ratio decreased with increasing birth weight (and gestational age), thus providing the first indication in vivo of the differential development of uridinediphosphate glucuronosyltransferases in humans.
Increased Renal Net Acid Excretion in Prematures below 1,600 g Body Weight Compared with Prematures and Small-for-Date Newborns above 2,100 g on Alimentation with a Commercial Preterm Formula
Authors: Kalhoff H. , Wiese B. , Kunz C. , Diekmann L. , Stock G.J. , Manz F.
Published: October 2009

In 76 low birth weight infants with an actual body weight ranging from 1,210 to 2,540 g and fed a commercial preterm formula, urine samples were collected and blood acid base status was measured on day 38 ( ± 17, mean ± SD) of life. Infants with an actual body weight below 1,600 g demonstrated a higher daily weight gain (22 ± 3 vs. 14 ± 5 g/kg/day), lower blood pCO2 (35.4 ± 5.0 vs. 38.9 ± 3.8 mm Hg), lower urine pH (5.8 ± 0.5 vs. 6.5 ± 0.3), higher renal net acid (1.86 ± 0.38 vs. 1.28 ± 0.55 mmol/ kg/day) and higher phosphorus excretion (0.67 vs. 0.52 mmol/kg/day) than infants with an actual body weight above 2,100 g. Urinary ionogram data of these 2 groups of infants show that the increased renal net acid excretion of the smaller prematures is the result of a lower urinary excretion of sodium, potassium and chloride, due to a higher daily weight gain, probably a higher retention of these minerals, and a higher urinary phosphorus excretion probably due to an age-specific lower intestinal calcium absorption, and therefore a lower rate of calcium and phosphorus retention. Considering the low renal capacity for hydrogen ion excretion, very low birth weight infants still run a considerable risk for disturbances of acid base metabolism due to the high mean level of net acid excretion in nutrition with preterm formulas and an additional age-specific augmentation of renal acid load.
Atrial Natriuretic Peptide in the Preterm Newborn
Authors: Stephenson T.J. , Broughton Pipkin F. , Hetmanski D. , Yoxall B.
Published: October 2009

Atrial natriuretic peptide (ANP), plasma renin and renin substrate concentrations (PRC and PRS) were measured in 31 preterm infants with idiopathic respiratory distress syndrome. Infants were studied at a mean of 1.4 days; 17 infants were also studied 2 days later. A 6-hour urine collection was made from 13 male infants on the first day of sampling to assess renal function. Both ANP and PRC were elevated and showed wide ranges of values (geometric means of 620 pg/ml and 18.4 ng/ ml/h). Plasma ANP was significantly correlated with pH, PaCO2 and base excess. No correlations with parameters of cardiovascular or renal function were found. Plasma ANP rose in 13 of the 17 paired samples. We suggest that the very high ANP concentrations in these babies are a consequence of the pulmonary haemodynamic disturbances which accompany respiratory distress in the newborn.
Growth-Factor-Like Substance in Amniotic Fluid in the Rat: Effect on the Development of Fetal Colonic Goblet Cells
Authors: Morikawa Yoshio , Yoshimura Mami , Okada Toshiya , Ohishi Iwao
Published: October 2009

Extra- and intrauterine fetuses were studied to explore the effect of amniotic fluid on the development of colonic goblet cells. Significant differences in the density of goblet cells in developing colon were observed during fetal days 19-22 between these two groups, suggesting that amniotic fluid affects the development of the colonic goblet cells, especially during the period between days 19 and 21 when rat fetuses began to swallow amniotic fluid, as demonstrated by injecting India ink into the amniotic cavity. By immunological dot blot analysis, the amniotic fluid and gastric juice from intrauterine fetuses were positive for epidermal growth factor (EGF), whereas maternal abdominal serous fluid and gastric juice from extrauterine fetus were negative for EGF. The present results indicate that the amniotic fluid during late gestation greatly affects the development of the colonic goblet cells in rat fetuses and that the trophic factor for the cells seems to be EGF or an EGF-like substance in the amniotic fluid.
Alteration of Maternal Growth Hormone Levels during Pregnancy Influences both Fetal and Postnatal Growth in Rats
Authors: Spencer G.S.G. , Robinson G.M. , Berry C.J. , Dobbie P.M.
Published: October 2009

To study the effects of exogenous growth hormone (GH) administration to the mother on fetal growth, dwarf rats with an isolated GH deficiency were given daily s.c. injections of GH throughout pregnancy. Fetuses were heavier in GH-treated mothers (p < 0.001), and pups from GH-treated mothers continued to grow faster (p < 0.001) than pups from control mothers throughout the postnatal growth period through to weaning. In normal Wistar rats, administration of a potent antiserum to somatostatin to pregnant rats increased the mean birth weight of the offspring (p < 0.01). Administration of GH to the mothers also significantly increased birth weight (p < 0.05), but administration of antiserum to rat GH resulted in a significant retardation of both fetal and placental growth (p < 0.001). These data suggest that maternal GH status is significantly involved in the growth of the fetal rat.
Postnatal Development of Ornithine Decarboxylase and Polyamines in the Mouse Kidney: Influence of Testosterone
Authors: Sánchez-Capelo Amelia , Peñafiel Rafael , Tovar Antonio , Galindo Jesés D. , Cremades Asunción
Published: October 2009

The role of ornithine decarboxylase (ODC) and polyamines in kidney growth during the postnatal development of mice and the influence of testosterone were investigated. A marked sexual dimorphism in renal size was evident after the 3rd week of life, corresponding with the rise in circulating testosterone and the increase in renal ODC and urinary excretion of putrescine in male mice. Renal putrescine and spermidine gradually decreased during the first 3 weeks of life and did not correlate with ODC activity. Treatments with Α-difluoromethylornithine, and ODC-specific inhibitor, and the antiandrogen flutamide during weeks 4 and 5 showed that both compounds decreased renal ODC activity but only flutamide impaired kidney growth, suggesting that renal growth in mice is regulated by androgens but is independent of the induction of ODC activity.
Influence of Disease State on Oxygen Transport in Newborn Piglets
Authors: Hammerman Cathy
Published: October 2009

Optimally, oxygen delivery (DO2) should be sufficient to provide for adequate oxygen consumption (VO2) while avoiding O2 toxicity. Physiologically a critical level of DO2 has been described, below which decreases in oxygen supply begin to impair VO2, leading to venous hypercarbia and tissue acidosis. We predicted that this critical level would be influenced by factors such as underlying disease state and oxygen needs. Newborn piglets were exposed either to hypoxia (n = 6) or to group-B Β-hemolytic streptococcal sepsis (n = 6). Hemodynamic parameters were measured; DO2 and VO2 were calculated and compared within and between the groups. Ê»Critical DO2’ was defined as the point at which decreases in DO2 began to produce concomitant decreases in VO2. This was observed at 9 ml/kg/min in hypoxic vs. 21 ml/kg/min in septic piglets. The Ê»critical Vsat’ was defined as the venous O2 saturation beyond which tissue acidosis, as defined by base excess, developed. Ê»Critical Vsats’ were 17% for hypoxic vs. 21% for septic animals. In summary, septic newborn piglets had higher critical DO2 and critical Vsat than hypoxic piglets, implying that they became oxygen supply dependent and developed tissue acidosis at higher levels of DO2 and Vsat, respectively.
Validation of Cardiac Output Measurements with Noninvasive Doppler Echocardiography by Thermodilution and Fick Methods in Newborn Piglets
Authors: Welch Elizabeth , Duara Shahnaz , Suguihara Cleide , Bandstra Emmalee , Bancalari Eduardo
Published: October 2009

Since cardiac output measured by the noninvasive pulsed Doppler technique has not been well correlated to results from the invasive thermodilution or Fick methods in neonates, the three methods were evaluated in 6 sedated newborn piglets (age < 7 days, weight 1.5 ± 0.7 kg) in room air and after 10 min of hypoxia. Doppler velocities were measured in the ascending aorta, and the aortic root diameter was measured in early diastole. A Swan-Ganz catheter in the left pulmonary artery sampled mixed venous blood for central venous O2 content and measured cardiac output by thermodilution. Oxygen consumption was measured by the open-circuit technique and used to determine cardiac output by the Fick method. In room air, values obtained by pulsed Doppler, thermodilution and Fick methods (0.270 ± 0.05, 0.246 ± 0.05 and 0.241 ± 0.05 liters/kg/min, respectively) were similar, with a correlation coefficient (r) between Doppler and thermodilution values of 0.89, Doppler and Fick values of 0.82 and thermodilution and Fick values of 0.88. Although hypoxia sometimes produced larger differences between paired values, correlation coefficients remained high (Doppler echocardiography vs. thermodilution, r = 0.96; Doppler vs. Fick methods, r = 0.92; thermodilution vs. Fick method, r = 0.95). The mean ± SD of the percent difference between values obtained by Doppler echocardiography and thermodilution was 4.2 ± 14.4% in room air and 12.8 ± 14.4% in hypoxia, whereas differences in values obtained by Doppler and Fick methods was 6 ± 14.9% in room air and 14.7 ± 8.5% with hypoxia. We conclude that pulsed Doppler echocardiography correlates well with the standard invasive methods for measuring cardiac output during normoxia and hypoxia in newborns, but a greater variability between individual results is sometimes seen during hypoxia.
Comparative Study of Four Tests of Bacterial Infection in the Neonate
Authors: Guillois Bernard , Donnou Marie Dominique , Sizun Jacques , Bendaoud Bruno , Youinou Pierre
Published: October 2009

In a prospective study, the diagnostic value of C3d serum levels was compared with that of neutropenia, hyperfibrinogenemia and raised CRP in generalized neonatal bacterial infections. Serum C3d was evaluated using a counter-immunoelectrophoresis technique following a step of removal of C3 split products. Twelve patients with septicemia, 8 patients with highly probable infection and 134 normal controls were included in the study. The sensitivities for neutropenia, hyperfibrinogenemia, raised CRP and positive C3d were 21, 45, 60 and 70%, respectively, with a significant difference between the sensitivities of neutropenia and positive C3d (p < 0.01). The specificities were found to be 99.2, 99.2, 100 and 97.7% respectively. Thus the C3d qualitative test appears to be as reliable as CRP in the diagnosis of neonatal bacterial infections.
Prognostic Significance of Spontaneous Motility in Very Immature Preterm Infants under Intensive Care Treatment
Authors: Albers S. , Jorch G.
Published: October 2009

Qualitative analysis of spontaneous motility was performed in 22 preterm infants (gestational age 25-31 weeks) on the intensive care unit. The infants were videorecorded once a week in the late afternoon during 1 h until 36 weeks of gestation. Quality of movement was analyzed by 8 observers using visual ‘Gestalt perception’ and compared with the neurological outcome 1 year after term. A normal quality of movement consistently predicted a normal neurological outcome with a probability of 90–100%. An abnormal quality of movement predicted an abnormal outcome with a probability of only 56% in the first, but with a probability of 82% in the third postnatal week. The average interobserver agreement was 78%. The analysis of spontaneous motility for the early diagnosis of neurological dysfunctions can reliably be applied on very immature preterms under intensive care conditions from the 3rd postnatal week on.
Regulation by Glucose Availability of Tension Development and Electrical Activity in Fetal and Neonatal Rat Hearts
Authors: Guarner Verónica , Hernández Efraín H. , Moreno Servando J. , Huerto Raúl , Gorostiza Patricia , Valenzuela Fermín
Published: October 2009

The aim of the present article was to study if changes in glucose availability modify the functional activity of the glucose-dependent developing heart. Our data indicate that a decrease in glucose availability increases tension development and action potential duration at early fetal stages. This fact could probably be explained by the enhancement of Ca2+ movements that regulate the number and turnover rate of membrane glucose transporters in muscle cells. The sensitivity to glucose availability decreases postnatally as the heart becomes fatty acid-dependent.
Effect of Intraventricular Hemorrhage on Pulmonary Function in Newborn Piglets
Authors: Farstad T. , Odden J.-P. , Bratlid D.
Published: October 2009

Intracranial hemorrhage in the premature infant is often associated with respiratory failure and need for mechanical ventilation. We therefore addressed the question of possible interactions with and pulmonary consequences of intraventricular hemorrhage. Newborn piglets were studied during intraventricular hemorrhage simulated by intraventricular blood infusion. Infusion volume amounted to 8% of estimated brain weight. Respiratory rate, minute ventilation, lung resistance and dynamic lung compliance, as well as arterial blood gases, arterial and intraventricular pressures were measured. The piglets were mechanically ventilated with a low basal rate of 20 breaths per minute throughout the study. All piglets experienced significant rise in intraventricular pressure and respiratory failure during the study. Respiratory failure was mainly a result of a reduction in respiratory frequency and minute ventilation until apnea. However, a rise in lung resistance was also noted while lung compliance did not change. We conclude that increased need for mechanical ventilation during intracranial hemorrhage is primarilty a consequence of hypoventilation. The increase seen in lung resistance could also suggest that intraventricular hemorrhage causes an element of bronchiolar constriction. Furthermore, these effects are not only a result of the increase in intraventricular pressure, but specific effects of blood components within the central nervous system must be considered.
Respiratory Abnormalities in Infants of Substance-Abusing Mothers: Role of Prematurity
Authors: Toubas Paul L. , Sekar K.C. , Wyatt Eric , Lawson Allyson , Duke James C. , Parker Michael D.
Published: October 2009

It is a current hypothesis that maternal history of drug addiction during pregnancy and detection of drugs in the urine of the newborn are associated with increased incidence of apnea. To test this hypothesis, we reviewed polygraphic studies of respiration in two groups of infants who had been exposed in utero to cocaine (and other drugs). The first group was composed of 20 term infants (39.1 ± 0.8 weeks gestation), and premature infants (35.4 ± 0.8 weeks gestation). None of the infants were on methylxanthines. These infants were matched with 15 term and 15 preterm infants of similar gestational age. Variables studied were: heart rate, respiration, chest impedance pneumography, nasal airflow and oxygen saturation (pulse oximetry). Apnea indices for central and obstructive events of short and long duration as well as periodic breathing and oxygen saturation were obtained. Term drug-exposed infants had less central apnea and a higher rate of periodic breathing compared to term controls, whereas drug-exposed premature infants had more obstructive apnea and less periodic breathing compared to premature controls. These observed differences within groups were subtle and clinically insignificant. Other parameters studied were not different. When term and preterm infants were compared, preterm infants had significantly higher central apnea, obstructive apnea and periodic breathing rates. These differences appeared to be related to gestational age differences, not to drug exposure. There was no evidence that exposure to cocaine and other drugs actually inhibited respiration.
Cocaine Exacerbates Hypoxia-lnduced Cell Damage in the Developing Brain: Effects on Ornithine Decarboxylase Activity and Protein Synthesis
Authors: Spraggins Y.R. , Seidler F.J. , Slotkin T.A.
Published: October 2009

The immature brain is resistant to cell damage from hypoxia, such as that experienced during parturition. Because cocaine causes cerebral ischemia, we examined whether cocaine interferes with this resistance. On postnatal days 1, 4 or 8, neonatal rats were given an acute injection of saline or cocaine (30 mg/kg s.c.) and were then exposed to 7% O2 for 2 h. At the end of the exposure period, activity of ornithine decarboxylase (ODC), an enzymatic marker for activation of cell damage/repair, was assessed in different brain regions. Across all ages and regions, cocaine by itself suppressed ODC, reflecting reduced cell metabolism in the face of ischemia; the protein synthetic rate, assessed with [3H]leucine incorporation, was largely preserved during the drug insult. On postnatal day 1, hypoxia alone also led to a reduction in forebrain ODC as part of the protective metabolic response, with preservation of protein synthesis despite restricted oxygen availability. However, when cocaine and hypoxia were combined, ODC was induced and protein synthesis fell, indicating the onset of cell damage. By 4 days of age, brain maturation produced a change in the metabolic response to hypoxia alone, characterized by ODC induction; when cocaine was present, the response to hypoxia was exacerbated. At 8 days of age, neonatal brain again showed ODC induction with hypoxia, but in this case, cocaine pretreatment reduced the effect on ODC. Measurements of the patterns of protein synthesis during and after hypoxia indicated that cocaine pretreatment was enhancing the cell damage component of the response (increased protein synthesis during hypoxia) and reducing the cell repair component (decreased ability to induce ODC). In contrast to the interaction of acute cocaine with hypoxia, chronic prenatal treatment with cocaine did not elicit exacerbation of the cell damage markers during a subsequent exposure to postnatal hypoxia; worsening of hypoxic cell injury thus occurs only when cocaine is present concurrently with the hypoxia, as would be expected from direct ischemic actions of cocaine. Enhanced sensitivity to hypoxia-induced brain cell damage could be an important contributing factor to the net effects of cocaine on brain development in light of the acute ischemia associated with ‘crack’ cocaine smoking, hypoxia/ischemia from cigarette smoking, or hypoxia during parturition.
Plasma Chromium Levels in Hypoglycemic Preterm, Full-Term and in Intrauterine-Growth-Retarded Babies
Authors: Kitapçı Füsun , Dilmen U&gcaron;ur , Akyol Ömer , Toppare Mete , Kaya Safa , Şenses Ali , Durak Ilker , Kılıç Ziya
Published: October 2009

Serum chromium levels of hypoglycemic preterm and full-term babies were investigated. Normoglycemic preterm and full-term babies were selected as the control group. There was no statistically significant difference in serum Cr levels between preterm and full-term, hypoglycemic and normoglycemic, preterm hypoglycemic and preterm normoglycemic, full-term hypoglycemic and full-term normoglycemic babies. Serum Cr levels of intrauterine-growth-retarded babies were relatively low compared to infants appropriate for gestational age. Serum Cr levels of babies with mothers younger than 35 years of age had significantly lower levels than older mothers’ babies.
Effects of Oral IGF-I or IGF-II on Digestive Organ Growth in Newborn Piglets
Authors: Xu Ruo-Jun , Mellor D.J. , Birtles M.J. , Breier B.H. , Gluckman P.D.
Published: October 2009

To study whether colostrum-borne growth factors are responsible for the rapid GI tissue growth in naturally suckled newborn animals, newborn unsuckled piglets were bottle-fed for 24 h with infant milk formula with or without addition of 2 μg/ml of recombinant human insulin-like growth factor-I (IGF-I) or insulin-like growth factor-II (IGF-II), a level which approximated that of porcine colostrum. The animals were then sacrificed for measurements of their digestive organ weights and contents of protein, RNA and DNA in the organs. The treatment with IGF-I or IGF-II failed to show any significant effect on the weight of the esophagus, stomach, small intestine, large intestine, mandibular glands, kidneys and the spleen, and had no effects on the contents of protein, RNA and DNA in the small intestinal mucosa, the liver and the spleen. However, piglets fed with infant formula containing IGF-I (n = 7) or IGF-II (n = 7) had a heavier pancreas (p < 0.05) compared to formula-fed controls (n = 7). The DNA content in the stomach and the pancreas were greater in animals treated with IGF-I or IGF-II than in controls. Using a cell labelling technique it was shown that both IGF-I and IGF-II stimulated cell proliferation in the small intestinal crypts. The results indicate that the substantial GI tissue growth reported in newborn animals is unlikely due to colostrum-borne IGF-I or IGF-II alone. On the other hand the study does suggest that oral IGF-I and IGF-II are capable of stimulating cell proliferation in the GI tract.