bluuebunny/crossref_metadata_2025 huggingface dataset:
Ovine Fetal Swallowing and Behavioral State Responses to Sublingual Water
Authors: Ross Michael G. , Dodd Adam , Agnew Connie , Fujino Yugi , Ervin Gore
Published: October 2009

Ovine fetal swallowing primarily occurs in bouts of activity associated with low voltage electrocorticogram activity and breathing movements. Despite similar rates of electromyographic swallowing activity, there are significant differences in the net esophageal fluid flow among fetuses. To determine if variations in the volume of fluids accessible to the fetus (amniotic fluid, lung fluid, salivary secretions) affect fetal swallowing, we studied the effects of sublingual distilled water infusions on ovine fetal swallowing rates and esophageal flow. Seven pregnant ewes at 127 ± 2 days gestation were chronically instrumented with maternal and fetal vascular catheters, fetal electrocortical, electro-ocular and electromyograph electrodes, an esophageal flow probe and a sublingual infusion catheter. Following a 2-hour control period, consecutive sublingual infusions of room temperature distilled water (10 and 20 ml/kg/h) were administered for 2 h each. In response to sublingual infusions, fetal plasma sodium (142.5 ± 0.5 to 140.8 ± 0.8 mEq/l), chloride concentrations (109.2 ± 0.4 to 107.7 ± 0.7 mEq/l) and osmolality (302 ± 2 to 298 ± 2 mOsm/kg) decreased significantly. Swallowing activity and esophageal flow did not change significantly from basal values (47 ± 9 swallows/h, 19.2 ± 4.2 ml/h) during the sublingual infusions. However, fetal low-voltage electrocortical activity increased significantly during both infusion periods (42 ± 3 to 56 ± 6%). Sublingual distilled water infusion decreases fetal plasma osmolality and alters fetal behavioral state without affecting swallowing frequency or esophageal flow.
Changes in Plasma Levels of Oxygen Radical Scavenging Enzymes during Extracorporeal Membrane Oxygenation in a Lamb Model
Authors: Möller J. , Gilman J.T. , Sussmane J. , Raszynski A. , Wolfsdorf J.
Published: October 2009

We studied levels of superoxide dismutase, glutathione, reductase, glutathione peroxidase and lipoperoxides in 12 healthy lambs below 1 year of age (8-19 kg) under therapy with extracorporeal membrane oxygenation (ECMO). Plasma levels of these free oxygen radical scavenging enzymes and lipoperoxides were taken 1 day before the ECMO experiment, at the beginning of ECMO after the first rotations of the roler pump, during, and after ECMO. The pre-ECMO results of days 1 and 2 were compared with the during-ECMO results and those with the post-ECMO results using the t test for paired samples. We found a significant decrease of both superoxide dismutase and glutathione reductase on ECMO, a trend to increased lipoperoxide levels, and unchanged levels of glutathione peroxidase. After discontinuing bypass the levels began to normalize again. We conclude that ECMO reduces some oxygen radical scavenging enzyme levels and exhibits a trend to increased lipoperoxide levels. Near total lung collapse with consecutive reperfusion injury might be harmful considering these results. However, the nonsignificant increase in lipoperoxide levels excludes considerable oxygen toxicity during this short ECMO trial.
Evidence of a Role for Growth Hormone, but Not for Insulin-Like Growth Factors-l or -II in the Growth of the Neonatal Rat
Authors: Robinson G.M. , Spencer G.S.G. , Berry C.J. , Dobbie P.M. , Hodgkinson S. , Bass J.J.
Published: October 2009

Neonatal rats were injected with antiserum raised against either insulin-like growth factor (IGF)-I IGF-II, rat growth hormone (rGH) or somatostatin (SRIF) on each of days 2-5 of life: controls received normal sheep immunoglobulin. Plasma levels of rGH and IGF-I were measured by radioimmunoassay and growth rates recorded. Neonatal administration of anti-rGH resulted in the suppression of plasma IGF-I levels at day 21 and of body weight gain compared with control animals from day 5 of age; relative growth velocity continued to diverge in the absence of any further treatment. Immunoneutralization of IGF-I or of IGF-II had no effect on growth rates of rats at any time during the experiment and had no effect upon plasma rGH concentrations at day 21. However, at day 7, plasma rGH was lower in anti-IGF-I-treated rats than in controls; in contrast, plasma rGH in anti-IGF-II-treated animals at day 7 was higher than in controls. Plasma levels of IGF-I at 49 days of age were similar regardless of the neonatal immunization treatment received. Anti-SRIF treatment of neonatal rats was associated with elevated rGH levels, but no significant stimulation of growth. These results indicated that growth hormone, but not circulating IGF-I or IGF-II are essential for normal growth in the neonatal rat.
Cerebral Hemodynamics and Oxygenation in Preterm Infants after Low- vs. High-Dose Surfactant Replacement Therapy
Authors: Dorrepaal Caroline A. , Benders Manon J.N.L. , Steendijk Paul , van de Bor Margot , van Bel Frank
Published: October 2009

In thirteen preterm infants receiving surfactant (Curosurf) replacement therapy, changes in cerebral hemodynamics and oxygenation were investigated by near infrared spectroscopy. Surfactant instillation led to an instantaneous increase in cerebral blood volume (CBV) in all infants, which was primarily due to an increase in deoxygenated hemoglobin. Five infants received a low dose (100 mg/kg =1.25 ml/kg) of surfactant and 8 a high dose (200 mg/kg = 2.50 ml/kg). A significantly larger increase in CBV was observed in the infants receiving a high dose compared to those receiving a low dose of surfactant. We conclude that cerebral perfusion is affected more after the instillation of a high dose compared to a low dose of surfactant.
Influence of NaCl Supplementation on Vasopressin Secretion and Water Excretion in Premature Infants
Authors: Sulyok E. , Rascher W. , Baranyai Zs. , Ertl T. , Kerekes L.
Published: October 2009

The study was carried out to assess the possible involvement of excess AVP and free water retention in the development of late hyponatremia by comparing the postnatal course of plasma AVP and urinary excretion of AVP and sodium as well as creatinine, osmolar and free water clearances in premature infants with (group S) and without (group NS) NaCl supplementation. Plasma total protein and albumin concentrations were also determined. Group NS consisted of 8 infants with a birth weight of 1,150–1,730 g (mean: 1,440 g) and gestational age of 28–32 weeks (mean: 30.4 weeks). Group S included 8 infants with a mean birth weight of 1,390 g (range: 980–1,700 g) and a mean gestational age of 30.1 weeks (range: 27–32 weeks). Measurements were made on the 7th day and weekly thereafter until the 5th week of life. NaCl supplementation was given in a dose of 3–5 and 1.5–2.5 mmol/kg/day for 8–21 and 22–35 days, respectively. Infants receiving sodium supplements had significantly greater urinary sodium excretion (p < 0.01), retained more sodium (p < 0.01), maintained plasma sodium at normal levels and gained weight at slightly higher rates when compared with those on low sodium. Plasma AVP tended to be higher in group S but did not differ significantly from that in NS group. Urinary AVP excretion, however, either expressed in ng/day or ng/l00 ml GFR, was significantly higher in group S, although the age-related increase could not be seen when correction was made for GFR. The respective values of AVP excretion in weeks 1,2-3 and 4-5 were 1.02 ± 0.17,3.19 ± 0.47 and 2.44 ± 0.22 ng/day in group S and 0.60 ± 0.12, 0.96 ± 0.12 (p < 0.001) and 1.61 ± 0.26 ng/day (p < 0.01) in group NS. NaCl supplementation and the increased AVP excretion was associated with significant decreases in GFR (p < 0.05), free water excretion (p < 0.01), plasma total protein (p < 0.01) and plasma albumin (p < 0.01) concentrations. These data suggest that NaCl supplementation prevents late hyponatremia at the expense of AVP-mediated water retention and subsequent volume expansion.
Changes in Static and Dynamic Skin Fold Measurements in the First 60 Hours of Life: Higher Values following Cesarean Delivery
Authors: Demarini Sergio , Pickens William L. , Hoath Steven B.
Published: October 2009

Infants born by cesarean section (CS) have been reported to have increased intracellular and total body water and have a slower postnatal decline in cell water content compared to vaginally delivered infants. These findings support the hypothesis that delivery-related changes in water compartmentalization will result in postnatal differences in tissue compressibility. In order to test this hypothesis, static and dynamic skin fold thicknesses (SFTs) were obtained in 60 healthy, term, appropriate for gestational age infants between 1 and 60 h of life. Thirty infants were delivered vaginally and 30 by CS. Midtriceps, subscapular and abdominal skin folds were measured twice daily during the first 3 days of life. There were no differences between groups in birth weight, length, head circumference, gestational age, sex or ponderal index. Our results showed that static SFTs were significantly greater in CS than in vaginally delivered infants at birth and remained so throughout the study period. In both groups, static SFTs increased while weight decreased over time. At birth, dynamic SFTs were significantly greater in infants delivered by CS. We speculate that skin fold differences between CS and vaginal deliveries may reflect a different dynamic of perinatal body water distribution. The mechanism underlying the paradoxical increase in static SFTs in both groups is unknown.
Insulin Reduces Basal Release of Atrial Natriuretic Factor by Isolated, Perfused Neonatal Pig Hearts
Authors: Sicard Raymond E. , Feit Lloyd , Werner John C.
Published: October 2009

Plasma atrial natriuretic factor (ANF) levels are markedly altered in diabetic rodents suggesting that insulin might be a modulator of ANF release. Effects of insulin (25 mU/ml) on basal (nonstimulated) immunoreactive (ir)-ANF release by isolated neonatal pig hearts paced at 150 beats/min and perfused with no change in atrial stretch were examined. Release of ir-ANF decreased with age from 1-3 days postpartum (146.0 ± 38.4 to 62.2 ± 20.5 fmol/g/min). Insulin stimulated myocardial glucose utilization and lactate production approximately 2-fold, but uniformly decreased ir-ANF release by approximately 25%, regardless of age. Correlations between ir-ANF release and myocardial metabolism suggest independent influences of insulin on these two events. In addition, it appears that this model might be reasonably exploited to investigate episodic ANF release and its regulation during ontogeny and in a variety of physiological states.
Early Life Environmental Deterioration, Nutrition and Ontogenesis of the Motor Cortex in the Rat: A Golgi Study
Authors: Fernández Victor , Pascual Rodrigo , Ruíz Samuel
Published: October 2009

Sprague-Dawley albino rats were subjected to an experimental paradigm in which environmental and nutritional variables were studied from birth to day 18. The use of Golgi-Cox-Sholl methodology allowed quantitative evaluations of neurons which were randomly impregnated with metallic mercury after fixation in a mercury salt. The nutritional treatment employed did not significantly influence the cytoplasmatic differentiation of cortical neurons although it was able to induce gross morphological modifications in body weight and size. By contrast, an impoverished surrounding during a limited period of time had a profound effect on the basal dendritic tree. The evidence presented here suggests the importance of the preweaning environment on the development of neural appendages. Motor pyramids of pups housed in deteriorated conditions underwent a progressive decrement in the length and number of peripheral branches and terminal dendrites. A decreased rate of cortical differentiation was also observed in overnourished pups as a result of reducing the litter size. This regressive event, can probably be attributed to social and sensory-motor limitations ofthe experimental group. However, to confirm this possibility, further research is required.
The Effect of Hypocapnia and Mechanical Pulmonary Stress on Lung Tissue in Newborn Lambs
Authors: Klöpping-Ketelaars W.A.A. , Havenith M. , Maertzdorf W.J. , Kuipers I.M. , Blanco C.E.
Published: October 2009

Positive pressure ventilation, using high inspiratory pressures, often causes lung damage. When associated with hypocapnia, it can produce severe focal alveolar alkalosis and can cause damage in areas of low blood flow. A vein-to-vein extracorporeal membrane oxygenator (ECMO) system was used to control blood gases independently of mechanical ventilation in 12 healthy newborn lambs. After connection to the ECMO system, ventilation was started with a peak inspiratory pressure of 35 cm H2O and a positive end-expiratory pressure of 5 cm H2O; the ventilator rate was 40/min with I:E = 1.5 and FiO2 = 1.0. In 6 of the 12 lambs sweep gases through the silicone membrane were regulated to assure arterial normocapnia. The other 6 were ventilated with the same settings and perfused with the same pump flow, but PaCO2 was allowed to fall to hypocapnic levels. The lambs were ventilated for 4h. Average pH and PaCO2 were 7.62 ± 0.14 and 2.11 ± 0.54 kPa, respectively, in the hypocapnic group and 7.39 ± 0.11 and 4.79 ± 0.51 kPa in the normocapnic group. After sacrificing the lambs, the lungs were inspected macroscopically and microscopically by computer-assisted morphometry to assess atelectasis and lung edema. Macroscopically there were no hemorrhages, barotrauma or widespread atelectasis of the lungs in either group. The thickness of interlobular lung septa in the right upper lobe was 32.5 ± 18.0 μm for the hypocapnic group and 29.7 ± 12.5 μm for the normocapnic group. The parenchymal-alveolar area ratio in the right upper lobe was 28.4 ± 5.04 and 24.6 ± 3.75% in the hypocapnic and normocapnic groups, respectively. Hypocapnia and mechanical stress for 4 h in initially healthy lungs did not produce alveolar epithelial damage.
Twenty-Four Hour Profiles of Glucose, Corticosterone and Adrenocorticotropic Hormone during the First Postnatal Day in Rats
Authors: Nagaya Marie , Widmaier Eric P.
Published: October 2009

Soon after birth, mammals are often confronted with the challenges of hypoxia, hypothermia and hypoglycemia. The incidence of the latter in the human population is roughly 2-20% of all live births. We characterized the glucose profile over the first 24 h of postnatal life in a large population of suckling, nonfasted rats. Approximately 63% were hypoglycemic (plasma glucose < 60 mg/dl) during the first 4 h after birth; from 6 to 24 h after birth this number was reduced to 10%. Low glucose levels in the first hours after birth were significantly associated with high plasma glucocorticoid and adrenocorticotropic hormone levels. Glucocorticoid injections 2 h after birth that elevated plasma corticosterone to high physiological levels for 1-2 additional hours significantly increase plasma glucose levels compared to vehicle-injected controls. These results suggest that, like the human newborn, rat pups are susceptible to developing neonatal hypoglycemia with about the same frequency as in babies. Also, the hypothalamic-pituitary-adrenocortical (HPA) axis appears to be active from birth and may be responsive to hypoglycemia stress during this early period (contrary to later neonatal ages when the HPA axis is quiescent in rats). Finally, glucocorticoids appear to prevent the development of hypoglycemia shortly after birth.
Pitfalls of Body Fat Assessments in Premature Infants by Anthropometry
Authors: Sheng H.P. , Muthappa P.B. , Wong W.W. , Schanler R.J.
Published: October 2009

Subcutaneous fat mass (SFM) and total fat mass (TFM) were estimated in 16 preterm infants at 8 ± 2 days postnatal age. SFM was estimated from anthropometric measurements: 5 skinfold thicknesses, 5 body circumferences, and regional body lengths. TFM was estimated from total body water measurements using dilution of isotopic water, H2180. The proportion of TFM that was SFM decreased with an increase in TFM. In infants with less than 100 g of TFM (5% body weight), 74% of TFM is in the subcutaneous layer compared with only 35% in infants with higher TFM (more than 100 g). Subscapular skinfold thickness is the best predictor of TFM (r = 0.78). Additional skinfold thickness measurements (triceps, biceps, suprailiac and thigh) do not improve the predictability of TFM by the subscapular skinfold thickness. We conclude that measurement of subscapular skinfold thickness is an appropriate choice for estimating fat deposition in preterm infants, particularly in field studies and in developing countries.
Effects of a Continuous Infusion of Tris(hydroxymethyl)aminomethane on Acidosis, Oxygen Affinity, and Serum Osmolality
Authors: Schneiderman Roy , Rosenkrantz Ted S. , Knox Isabella , Cramer Rose , Smoloski Robert , Raye John R.
Published: October 2009

The effects of a continuous infusion of tris(hydroxymethyl)-aminomethane (THAM) on pH, base excess, p50, serum osmolality, and plasma drug concentration during respiratory acidosis were studied in newborn piglets. Measurements were made during three experimental periods: (1) control period with normal blood gases; (2) hypercapnia period, and (3) hypercapnia plus THAM period (THAM infusion: 1.65 mmol/kg/h). pH decreased and paCO2 increased between control period (7.40 ± 0.05 and 45 ± 3 mm Hg) and hypercapnia period (7.24 ± 0.06 and 59 ± 2 mm Hg; p < 0.001; mean ± SD). pH returned to baseline (7.37 ± 0.04) during the hypercapnia plus THAM period, while paCO2remained elevated (63 ± 4 mm Hg). p50 increased from 30.7 ± 5.9 to 38.3 ± 4.7 (p < 0.05) during hypercapnia and decreased with hypercapnia plus THAM. THAM concentration and base excess increased with time and were linearly related. Serum osmolality was unchanged during the THAM infusion. We conclude that continuous infusion of THAM is effective in normalizing pH during respiratory acidosis in the piglet.
Effect of Maternal Hyperglycemia on NaK ATPase Activity in Fetal Rat Kidney
Authors: Freund Nicole , Bost Frédéric , Prieur Béatrice , Bismuth Jeanne , Geloso Jean-Pierre , Delaval Evelyne
Published: October 2009

The effect of moderate hyperglycemia on renal ATP production and ATPase activity of rat fetus was investigated using the experimental procedure of maternal continuous infusion of glucose during the last 5 days of gestation. Glucose-infused mothers and their fetuses showed a high level of glycemia (8.8 and 5.5 mM, respectively) and a high level of insulinemia (3 times higher than in controls). No change in either ATP or ADP concentration was detectable but an increase in NaK ATPase activity occurred without any change in Mg ATPase activity. These modifications should be the result of an enhanced Na/glucose cotransport leading to an enhanced extrusion of Na at the basolateral membrane. These results indicate that immature kidney is able to increase NaK ATPase activity to maintain Na homeostasis.
Postnatal Changes in Receptor-Mediated Rabbit Gastric Smooth Muscle Relaxation
Authors: Hyman P.E. , Hou H.X. , Willenbucher R. , Snape, Jr. W.J. , Tomomasa T.
Published: October 2009

The aims of this study were to identify mediators of relaxation in rabbit proximal gastric circular smooth muscle and to assess age-dependent changes in tissue response. Vasoactive intestinal peptide (VIP), adenosine, and norepinephrine induced tetrodotoxin-insensitive, concentration-dependent relaxation in bethanechol-precontracted (3 µM) gastric muscle strips from newborns and weanlings. Maximally effective concentrations of 10 µM VIP induced complete relaxation in newborns, but only 30% relaxation in weanlings (p < 0.01). Maximally effective concentrations of adenosine induced complete relaxation at both ages. Adenosine (ED50 3 µM) was more potent than adenosine triphosphate, indicating the presence of P1 purinergic receptors. In newborns norepinephrine induced complete relaxation (ED50 0.5 µM). The response to norepinephrine changed in age-dependent increments from relaxation in newborns to strong contraction in weanlings. In weanlings phentolamine inhibited norepinephrine-stimulated contraction, revealing persistent propranolol-sensitive relaxation. Tetrodotoxin and atropine had no effect on norepinephrine-stimulated contraction. In summary, in rabbit gastric circular smooth muscle: (1) VIP, adenosine, and norepinephrine induce relaxation; (2) VIP loses efficacy with age; (3) there is a β-adrenergic receptor mediating relaxation in the newborn which persists, and (4) an α-adrenergic receptor mediating contraction emerges early in postnatal life. Age-dependent changes in response to VIP and norepinephrine may contribute to the postnatal maturation of the gastric motility.
Thoracic Duct Lymph Flow in Fetal Sheep with Increased Venous Pressure from Electrically Induced Tachycardia
Authors: Gest Alfred L. , Bair Derek , Vander Straten Mary C.
Published: October 2009

The intent of this study was to investigate thoracic duct lymph flow, as it is related to the development of hydrops fetalis during rapid atrial pacing. We studied 6 fetal sheep at 128 ± 6 days of gestation who had chronically placed thoracic duct catheters, aortic and superior vena cava catheters, and atrial pacing electrodes. Atrial pacing at 317 beats/min caused an elevation in central venous pressure from a baseline value of 3 Torr to 7 Torr without affecting pH, arterial blood gas tensions, aortic blood pressure, total protein concentration, or colloid osmotic pressure, although there was a small rise in hematocrit. The thoracic duct lymph flow rate at baseline was 41 ± 6 ml/h. After atrial pacing for 6 h, the lymph flow rate as measured over at least three consecutive 10-min intervals, and presumably the transvascular fluid filtration rate, increased to 67 ± 7 ml/h if it was collected at an outflow pressure of 3 Torr, equal to the venous pressure prior to the onset of atrial pacing. However, if the lymph was collected instead at an outflow pressure of 7 Torr, equal to the actual venous pressure measured with rapid atrial pacing, then the lymph flow rate diminished to 48 ± 5 ml/h. This difference in lymph flow secondary to the increase in venous pressure could account for a maximum of 19 ml/h of edema that accumulates in fetal interstitium and body cavities with atrial pacing. We conclude that the increased venous pressure measured after rapid atrial pacing for 6 h not only increases the transvascular fluid filtration rate, but it also impairs the return of lymph flow to the circulation.
The Failure of Newborn Mice Infected with Escherichia coli to Accelerate Neutrophil Production Correlates with Their Failure to Increase Transcripts for Granulocyte Colony-Stimulating Factor and Interleukin-6
Authors: Liechty Kenneth W. , Schibler Kurt R. , Ohls Robin K. , Perkins Sherrie L. , Christensen Robert D.
Published: October 2009

We quantified circulating and storage neutrophils, their precursors and progenitors, and mRNA for some of the cytokines involved in granulocytopoiesis, in newborn and adult mice following intrapulmonary inoculation of Escherichia coli. Four hours following inoculation of adult and newborn mice with a quantity of organisms 2 logs below the LD100, all animals were neutropenic. After 24 h, adults had recovered from the neutropenia but neonates had not (p < 0.001). Accelerated neutrophil production was evident in the infected adults, and correlated with the appearance of granulocyte colony-stimulating factor (G-CSF) transcripts in the liver, spleen, and lung, and interleukin-6 (IL·6) transcripts in the spleen and lung. An increase in neutrophil production was not observed in the neonates, and none of their organs tested had transcripts for either G-CSF or IL·6, but they did have transcripts for cytokines not involved in granulocytopoiesis; macrophage colony-stimulating factor and its receptor (c-fms). We speculate that the failure to increase neutrophil production in infected neonatal mice is the result of failure to increase production of relevant cytokines.
Immune Response after Surfactant Treatment of Newborn Infants with Respiratory Distress Syndrome
Authors: Bambang Oetomo S. , Bos A.F. , de Lei L. , Okken A. , van Sonderen L. , Halliday H.L. , Walti H.
Published: October 2009

We examined the sera of 68 newborn infants with respiratory distress syndrome; 49 were treated with a natural porcine-derived surfactant preparation and 19 were controls. Serum of the patients was collected before, 3 weeks and 3 months after surfactant treatment. To detect any antibody that had been raised, we applied diluted serum of the babies in an indirect immunoperoxidase staining technique on frozen pig lung tissue specimens. With light microscopy an immune response could be appreciated as a brown reddish deposit in the porcine lung tissue specimens in 4 out of the 49 surfactant-treated and not in the control babies.
Expression of CD45R0 Antigen on the Surface of Resting and Activated Neonatal T Lymphocyte Subsets
Authors: Maccario R. , Chirico G. , Mingrat G. , Aricò M. , Lanfranchi A. , Montagna D. , Moretta A. , Rondini G.
Published: October 2009

Expression of CD45R0 antigen has been evaluated on the surface of T lymphocyte subsets obtained from cord blood and on peripheral blood lymphocytes (PBL) from both term and preterm neonates. In some experiments, expression of the same antigen has also been evaluated after in vitro activation of cord blood lymphocytes (CBL) with phytohemagglutinin (PHA) or in mixed lymphocyte culture. The CD45R0 molecule was found to be present on a significantly lower percentage of CD3+, CD4+ and CD8+ CBL as compared with the same subsets evaluated in adult individuals. Moreover, at variance with adult PBL, the great majority of CBL displayed a low level of fluorescence when stained with UCHL1 (CD45R0-specific monoclonal antibody), and both PHA and allogeneic stimuli were able to strongly increase the expression of the CD45R0 molecule on CBL. The percentage of CD45R0+ PBL obtained from both term and preterm neonates on the 1st day of life was comparable to that of CBL, however the expression of this molecule increases remarkably within a few days in the majority of term neonates, while it seems to take more time for the antigen to be fully expressed in preterm infants.
Transport of Triiodothyronine by Erythrocytes from Premature and Term Infants
Authors: Nagashima Kanji , Onigata Kazumichi , Yagi Hideki , Kuroume Takayoshi
Published: October 2009

To analyze hypothyroxinemia in low birth weight (LBW) infants, the initial uptake of T3 into erythrocytes from term and premature infants was measured. Thirty-eight infants and 18 prepubertal children as controls were subjected in this study. The infants were divided into group 1 (premature infants; below 2,500 g, n = 12) and group 2 (term infants; 2,501–3,500 g, n = 26). Infants with LBW for gestational age were excluded from this study. Vmax for group 1 (mean ± SE, 6.4 ± 0.5 pmol/min/108 cells), having low thyroid hormone levels, was significantly less than in group 2 (9.0 ± 0.7 pmol/ min/108 cells; p < 0.05). Mean Vmax for both groups exceeded normal controls (3.9 ± 0.3 pmol/min/108 cells; p < 0.01). Km in the perinatal period varied widely and was essentially the same as in the normal controls. These findings indicate that T3 uptake by erythrocytes of newborns may possibly be high regardless of maturation stage and blood levels of thyroid hormones may be reflected not by change in the affinity of the transport system but by that in the number of membrane carriers.
Effect of Opioid-lnduced Analgesia on β-Endorphin, Cortisol and Glucose Responses in Neonates with Cardiorespiratory Problems
Authors: Pokela Marja-Leena
Published: October 2009

The effects of analgesia on plasma β-endorphin (β-E), serum cortisol and blood glucose responses were investigated in 20 distressed, mechanically ventilated neonates during the first 3 days of life. Morphine 0.1 mg/kg, meperidine 1 mg/kg or alfentanil 10 µg/kg were used for analgesia as clinically indicated. Plasma β-E, serum cortisol and blood glucose were recorded before analgesia and 1 and/or 2, 12 and 24 h afterwards in the distress group and once in 20 healthy neonates (control group). β-E, cortisol, and blood glucose before analgesia were significantly higher in the distress group than in the control group. Cortisol values had decreased significantly 2 h after analgesia and blood glucose within 12 h. Plasma β-E values had decreased to the same level as in the controls 24 h after the start of analgesia. The results indicate that the stress response in the distressed neonates with cardiorespiratory problems, as assessed by β-E, cortisol, and blood glucose, is attenuated by opioid medication, and it is concluded that these patients should be given adequate analgesia.
Ontogeny of Small Intestinal Glutaminase and Glutamine Synthetase in the Rat: Response to Dexamethasone
Authors: Meetze William H. , Shenoy Vivek , Martin Gaines , Musy Pierre , Neu Josef
Published: October 2009

The ontogeny of small intestinal glutaminase (GA) and glutamine synthetase (GS) was studied with relation to the maternal administration of dexamethasone (DEX). Pregnant Sprague-Dawley rats were administered 0.2 mg/kg of DEX or saline twice daily on days 19 and 20 of gestation. Activity of GA did not increase from the fetus to the 10-day-old rat; however, GS activity increased 7-fold. DEX induced doubling of GA activity and mRNA, but only a slight increase is GS activity and mRNA was observed in the fetus. GA and GS activities appear to be regulated by different mechanisms.
Ontogeny of Rat Lung Type IV Collagenase mRNA Expression and Collagenolytic Activity during the Perinatal Period
Authors: Malicdem Milagros , Taylor Wiley , Goerke Mary , Devaskar Uday
Published: October 2009

The extracellular matrix is important in the cellular differentiation and morphogenesis of the lung. The basement membrane (BM), an integral part of the extracellular matrix, is composed primarily of type IV collagen. The metabolism of type IV collagenase is important in remodeling of BM that occurs during growth. We examined the ontogeny of rat lung type IV collagenase mRNA expression, type IV collagenolytic activity and type IV collagen content during the perinatal period. In addition, the effect of prenatal glucocorticoid (GC) treatment on fetal lung type IV collagenase mRNA expression and type IV collagenolytic activity was studied. Lung polyadenylated RNA was extracted and subjected to Northern blot analysis and laser densitometry after hybridization with human type IV collagenase (∼72 kD) and rat actin cDNA probe. Type IV collagenolytic activity and type IV collagen concentration were quantitated by an enzymatic and a radioimmunoassay, respectively. While lung type IV collagenase mRNA to α-actin ratio and type IV collagenolytic activity were highest prior to birth (21-day fetus), the lung type IV collagen concentration was lowest at this time. Prenatal GC treatment did not influence type IV collagenase mRNA expression or the collagenolytic activity. A role for fetal lung type IV collagenase in preparation for the neonatal pulmonary vascular and/or alveolar adaption is proposed.
Induction and Distribution of Cellular Retinol-Binding Protein, Type Two during Villus-Crypt Development in the Chick Duodenum
Authors: Goda Toshinao , Pacifici Maurizio , Takase Sachiko
Published: October 2009

Between day 18 of embryogenesis and 1 day posthatch, a rapid and remarkable (over 10-fold) increase in cellular retinol-binding protein, type two (CRBP(II)) levels occurred in the lower portion of duodenal villi of the chick. With further postnatal growth and concomitant with initiation of food intake, CRBP(II) levels increased over 2-fold in the mid-villus enterocytes. The results suggest that a first induction of CRBP(II) occurs in differentiating lower villus enterocytes during the perinatal period and is followed by marked increases in mid-villus cells. These quantitative change in the distribution and levels of CRBP(II) are probably related to the appearance of retinol in the duodenal lumen.
Control of Skin Blood Flow in Pre- and Full-Term Infants
Authors: Beinder E. , Trojan A. , Bucher H.U. , Huch A. , Huch R.
Published: October 2009

The response of skin blood flow to local ischemia, heating and cooling was investigated at different intervals after birth in 10 healthy full-term babies and 10 preterm postincubator infants using 2 noninvasive and locally neutral methods of microcirculatory measurement: laser Doppler flowmetry and cutaneous oxygen partial pressure (cPO2) estimation with a probe temperature of 37°C. Both groups of infants were capable of myogenic and neural control of skin blood flow. Higher cPO2 values under basal conditions and during reactive hyperemia suggest a raised nutritive capillary blood flow in the preterm group. The increase in cutaneous blood flow during local warming and reactive hyperemia shows that even in neonates on the first day of life no maximal skin vasodilatation is present. An increase in the periodic flow waves attributed to arteriolar vasomotion in 19- to 22-day-old infants, compared to the preterm group and younger babies, indicates that myogenic activity in skin arterioles increases with advancing age.
Nonvagal Reflex Apnea in the Newborn Kitten and during the Early Postnatal Period
Authors: Khater-Boidin Josette , Wallois Fabrice , Toussaint Patrick , Duron Bernard
Published: October 2009

The aim of this work was to study the nonvagal mechanisms which might induce apneic reflexes in kittens. Experiments were performed on spontaneously breathing animals (19 kittens at different postnatal ages). Animals were anesthetized (halothane) or decerebrated by transcollicular section of the brainstem. Weakly nociceptive cutaneous stimulations and various oral stimulations were administered in all animals. In 10 kittens, one of the lingual nerves was stimulated electrically. In 3 decerebrate kittens the effects of serotonin on respiratory activity and on muscles innervated by the hypoglossal nerve were studied. All the stimulations produced apneas of variable duration, and expiratory reinforcement was associated with activation of pretracheal muscles. Similar effects were observed after applying serotonin to the floor of the 4th ventricle. Thus serotonin may be involved in the mechanisms that cause some apneas.
Fibronectin Synthesis Bioactivity in Human Breast Milk
Authors: Fukushima Naobumi , Nagashima Kanji , Kuroume Takayoshi
Published: October 2009

To evaluate the effect of milk feeding on fibronectin in the perinatal period, fibronectin synthesis bioactivity (FnSA) in human breast milk was examined. FnSA was measured by bioassay using the cell-lined fibroblast. For the characterization of the FnSA, the milk samples were chromatographed. In gel chromatography (Sephadex G-100), three fractions of FnSA were detected. Two fractions overlapped with those of immunoreactive epidermal growth factor (ir-EGF). The other was present in the low-molecular-weight portion. In the high-performance liquid chromatography, two of four fractions with FnSA presented ir-EGF. One of two fractions with FnSA in heparin-binding affinity chromatography almost coincided with the portions of basic brain fibroblast growth factor (ir-bFGF). From these findings, we speculated that human milk has the bioactivity of fibronectin synthesis and it is composed of EGF, FGF, and unknown low-molecular-weight factors. Although the clinical meanings of FnSA have not been clarified, our data indicate a new characteristic of human milk.
Serum Erythropoietin in Small for Gestational Age Fetuses
Authors: Lemery Didier J. , Santolaya Joaquin , Serre Anne F. , Denoix Stephanie , Besse Guy H. , Vanlieferinghen Philippe C. , Bezou Marie J. , Gaillard Ginette , Jacquetin Bernard
Published: October 2009

Serum erythropoietin (Epo) concentration was compared prenatally in adequate (AGA) and small for gestational age (SGA) fetuses. Fifty-four percutaneous umbilical blood samplings were paired with maternal blood and assessed for Epo, hematocrit and reticulocyte count. Seventeen fetuses were growth-retarded (SGA) on the basis of ultrasonic biometry and birth weight. Controls (AGA; n = 37) underwent cordocentesis for risk of toxoplasmosis, maternal age or malformations (CNS, GI, heart). No cytogenetic abnormality or infections was found in the 54 fetuses. Linear and polynomial regressions were fitted to determine correlations between parameters. Nonparametric Mann-Whitney test was used for comparison between groups. Gestational age at sampling was similar in AGA and SGA. The SGA fetuses had a higher Epo concentration than controls (p < 0.001). Fetal AGA Epo increased significantly throughout pregnancy (p < 0.01) but did not correlate with maternal Epo (p > 0.05). An inverse correlation was found between fetal reticulocyte count and Epo concentration (p < 0.02). The mechanism of high Epo level in SGA fetuses may involve low pO2 and hemoconcentration.
Growth Hormone, Insulin-Like Growth Factor-l and Prolactin in Small for Gestational Age Neonates
Authors: Varvarigou Anastasia , Vagenakis Apostolos G. , Makri Maria , Beratis Nicholas G.
Published: October 2009

Growth hormone (hGH), insulin-like growth factor-I (IGF-I) and prolactin (PRL) were measured in the cord and venous blood of small for gestational age (SGA) neonates in order to evaluate their endocrine status during the first 3 days of life. Although there were SGA newborns with both high and normal levels of hGH, the mean ( ± SD) concentration of hGH in the cord blood of the SGA neonates was 72.1 ± 50.6 ng/ml, whereas in the appropriate for gestational age (AGA) newborns it was 37.0 ± 23.5 (p = 0.001). The IGF-I in the cord blood of the SGA and the AGA newborns was 194.2 ± 174.8 ng/ml and 77.3 ± 50.2, respectively (p = 0.013). The PRL in the SGA and AGA newborns was 184.8 ± 62.4 ng/ml and ± 60.5, respectively (p = 0.0005). On the 3rd day the hGH in the SGA babies was 50.7 ± 41.2, whereas in the AGA it was 24.3 ± 12.3 (p = 0.034). On the same day the IGF-I was ± 120.9 and 44.8 ± 31.6, respectively (p > 0.05). Similarly, the PRL was 157.1 ± 52.3 and 90.9 ± 52.5, respectively (p = 0.0008). All neonates with high hGH concentrations had low IGF-I levels, whereas of those with normal hGH half had high and half normal IGF-I levels. There was no difference in the hormone levels between symmetric and asymmetric intrauterine growth-retarded infants. The findings suggest that the SGA neonates are heterogeneous comprising three groups. The neonates with high hGH and low IGF-I may have resistance at the level of the hGH receptor or a defect in IGF-I synthesis, whereas those with normal hGH and high IGF-I may have a post-IGF-I receptor defect, with compensatory increase in IGF-I synthesis independent of hGH control.
Ethamsylate and Lung Permeability in Ventilated Immature Newborn Rabbits
Authors: Amato Maurizio , Sun Bo , Robertson Bengt
Published: October 2009

The leakage of proteins in the immature neonatal lung can reduce the effect of exogenous surfactant. The effect of ethamsylate, a more specific prostaglandin inhibitor than indomethacin and aspirin-like drugs, on alveolar albumin leak was studied in a group of 27 immature newborn rabbits (gestational age 27 days). A pilot study was carried out using 4 animals and low-dose ethamsylate (10 mg/kg). A second group of animals (n = 12) received at birth, by intravenous injection, ethamsylate (50 mg/ kg) and 10% human albumin (7 ml/kg). Animals not receiving ethamsylate (n = 11) served as control group. After 30 min of artificial ventilation with standard tidal volume (10 ml/kg) the lungs were lavaged and the amount of human albumin in lung lavage fluid was determined by immunodiffusion. No statistically significant differences were found in lung-thorax compliance and vascular to alveolar albumin leak between ethamsylate-treated animals and controls (p > 0.5). However, there was a statistically significant negative correlation between protein leak and lung compliance (r = ––0.41; p < 0.04). These results suggest no direct influence of early ethamsylate administration on neonatal lung permeability in the immature neonate confirming that lung permeability is inversely related to compliance.
Effect of Unilateral Perinatal Hypoxic-Ischemic Brain Damage on the Gross Development of Opposite Cerebral Hemisphere
Authors: Towfighi Javad , Housman Cathy , Vannucci Robert C. , Heitjan Daniel F.
Published: October 2009

The effect of unilateral perinatal cerebral hypoxic-ischemic damage on the gross development of the opposite hemisphere was investigated in immature rats. Eight-day-old rats underwent unilateral common carotid artery ligation followed by exposure to hypoxia (8% oxygen) ranging from 1 to 2 h at 37°C. The animals were sacrificed 3 weeks later, and brain damage was assessed histologically, by weighing the cerebral hemispheres, and by measuring hemispheric cross-sectional area and diameter as well as the thickness of neocortex. There were no significant differences in either the size or cortical thickness of the cerebral hemisphere contralateral to the damaged hemisphere compared to those of controls. The results are comparable to the effect of unilateral perinatal hemispheric decortication and hemispherectomy on the growth of the contralateral hemisphere and suggest that: (1) perinatal damage to one cerebral hemisphere does not significantly alter the size of the other hemisphere, and (2) the contralateral hemisphere may be used as a ‘normal’ reference in evaluating the extent of atrophy or infarction of a cerebral hemisphere damaged earlier by perinatal hypoxia-ischemia.
Prostaglandin E2 Accelerates Enzymatic and Morphological Maturation of the Small Intestine in Suckling Rats
Authors: Marti A. , Fernandez-Otero M.P.
Published: October 2009

The effect of prostaglandin E2 (PGE2) injection on the postnatal maturation of the 16-day-old rodent small intestine was studied. Previous studies have shown that 16,16-dimethyl PGE2 induced several morphological and biochemical parameters in the small intestine of 11-day-old rats. PGE2 was given subcutaneously daily at doses of 2 and 4 mg/kg body weight on postnatal days 11–15. After treatment there was a rise in the mean activities of sucrase, maltase, lactase and aminopeptidase. In rats receiving 4 mg/kg PGE2, sucrase activity was strongly stimulated (p < 0.001) in the proximal and the distal small bowel. In the duodenum, PGE2 treatment (4 mg/kg body weight) produced a significant increase in crypt depth (35%, p < 0.001), although villus height was not modified. Serum corticosterone levels were significantly increased in PGE2-treated rats. The results seem to indicate that PGE2 accelerates enzymatic and morphological intestinal maturation and this effect could be mediated by an increase in corticosterone.
Birth-Related Changes of Expression and Turnover of Some Neuroactive Agents and Respiratory Control
Authors: Lagercrantz Hugo , Pequignot Jean-Marc , Hertzberg Torbjörn , Holgert Hans , Ringstedt Thomas
Published: October 2009

Respiratory movements are partially inhibited before birth and central and peripheral chemoreceptors are probably less sensitive. The transition to continuous breathing might be due to the switch-off of inhibitory neuromodulators and the switch-on of excitatory neuroactive agents. This hypothesis has been explored mainly in rats. One example is dopamine which was found to have a high turnover in carotid bodies in newborn pups prior to decreasing rapidly. It is suggested to inhibit the carotid bodies before birth. In the brain, the noradrenergic system has been found to be activated at birth, possibly promoting neural transmission and arousal. Increased expressions of mRNA for c-fos, tyrosine hydroxylase and some neuropeptides have also been found.
In Search of the Real Respiratory Neurons: Culture of Medullary Fetal Cells Sensitive to CO2 and Low pH
Authors: Rigatto Henrique , Fitzgerald Sandra F. , Willis Maria A. , Yu Chang
Published: October 2009

Although extensively pursued, the real respiratory neurons have remained elusive. We departed from the more conventional physiologic and morphologic methods of system and tissue examination and cultured dissociated fetal rat cells from the areas of the nucleus ambiguus and the nucleus tractus solitarius located within the 2 mm rostral to the obex. Pacemaker-like cells, with a regular single or bursting activity, studied at 3-5 weeks of age, responded to very small pulses of CO2 (50 ms) and low pH with an increase in spike frequency and a decrease in amplitude. Other irregularly beating or silent cells did not respond or else required very large pulses (> 200 ms) to do so. The pacemaker cells also responded to hypoxia induced by administration of sodium hydrosulfite with an increase in spike frequency and amplitude; high oxygen (> 600 Torr) and adenosine produced a decrease in electrical activity. Most of these cells were multipolar after staining with antibodies to neuron-specific enolase and fragment C of tetanus toxin. They did not stain for choline acetyltransferase. The results suggest that these cultured cells, expressing a phenotype inherently responsive to CO2 and low pH, have the characteristics of central respiratory chemoreceptors, and may be involved in the generation of the respiratory rhythm.
Arcuate Nucleus Hypoplasia in Sudden Infant Death Syndrome: A Review
Authors: Filiano James J.
Published: October 2009

Abnormalities in central ventilatory control during sleep and/or impaired arousal have been reported in some infants who subsequently die of SIDS. Hypothetically, these abnormalities may result from dysfunction of the ventral medullary rim, considered to be an integrative site for cardioventilatory control on the basis of research in animals. This paper summarizes comparative neuroanatomic evidence from a previously published study showing that the human medullary arcuate nucleus is homologous to neurons in the cat which participate in chemosensory/autonomic integrative processes of the ventral medullary rim. Next, it summarizes a study of serially or extensively sectioned medullae of 41 SIDS and 27 controls which identified 2 SIDS victims with isolated hypoplasia of the arcuate nucleus confirmed by three-dimensional reconstructions and volume measurements. The volume of the right arcuate nucleus in the SIDS case was 0.7 mm3, compared to a range of 3.4–26.3 mm3 (median 5 mm3) in 3 infant controls. On the basis of pre-cerebellar and other anatomic connections of the arcuate nucleus and of neurons in homologous positions in animals, arcuate hypoplasia may lead to death by dyssynergy between the cerebellum’s influence on cardioventilation and the way this influence is integrated with chemosensation and arousal during sleep and hypercarbia during a critical developmental period.
Brain Stem Chemosensitivity; Its Implication in Central Respiratory Regulation
Authors: Morin-Surun M.P. , Boudinot E. , Schäfer T. , Denavit-Saubié M.
Published: October 2009

Central brain stem chemosensitivity plays an essential role in acid-base regulation. The site of the chemosensitive neuronal elements has not yet been clearly established. To address this question, we used an in vitro adult guinea pig isolated brain stem preparation, maintained in survival conditions by intrabasilar and bath perfusions of Krebs solution saturated with 95% O2 and 5% CO2. Hypercapnic stimulation, produced by modifying the CO2 concentration of the medium perfusing brain stem structures via the basilar perfusion system, increased the respiratory burst frequency recorded from the hypoglossal nerve. Hypercapnia evoked by ventral surface superfusion increased the respiratory burst amplitude. These data suggest that chemosensitive neuronal elements could be located at the ventral surface as well as in the deeper brainstem structures. However, their characteristics may be different.