bluuebunny/crossref_metadata_2025 huggingface dataset:
Lipoxygenase Activity in Rat Embryos and Its Potential for Xenobiotic Oxidation
Authors: Roy Sandip K. , Mitral Ashoke K. , Hilbelink Don R. , Dwornik Julian J. , Kulkarni Arun P.
Published: October 2009

This paper reports dioxygenase activity in rat embryos and demonstrates for the first time the ability of rat embryo lipoxygenase (LO) to oxidize xenobiotics in vitro. Significant dioxygenase activity towards linoleic acid was found in cytosol isolated from rat embryos in different developmental stages on day 9 and 10 of gestation. All four xenobiotics tested were oxidized at significant rate by the LO in the presence of linoleic acid. Both dioxygenase activity and benzidine oxidation were inhibited by the known inhibitors of LO, i.e. nordihydroguaiaretic acid and eicosatriynoic acid. These findings suggest that LO may be an important pathway for xenobiotic metabolism in the rat embryo.
Effects of Epidermal Growth Factor on Ornithine Decarboxylase Activity and DNA Synthesis in Rats during the Perinatal Period
Authors: Yamamoto D. , Hiramatsu Y. , Eguchi K. , Kudo T.
Published: October 2009

The effects of epidermal growth factor (EGF) on ornithine decarboxylase (ODC) activity and DNA synthesis were studied during the perinatal period in rats. EGF administration to neonatal rats increased ODC activity and DNA synthesis in neonatal rat liver, but not in brain. EGF administration to maternal rats increased ODC activity in maternal rat liver, but not in rat placenta and fetal rat liver. These data suggest that EGF has mitogenic effects on neonatal and maternal rat liver and play some important roles in fetal and neonatal growth.
Breast Feeding and Formula Feeding Affect Differently Plasma Thyroid Hormone Concentrations in Infant Baboons
Authors: Lewis Douglas S. , McMahan Alex , Mott Glen E.
Published: October 2009

We tested the hypothesis that plasma thyroid hormone levels in infant baboons are differentially affected by breast-feeding and nursery rearing. Infant baboons were breast-fed (n = 17), or fed formulas with a high polyunsaturated to saturated fat ratio (P/S) (n = 13), or a low P/S formula (n = 14). Plasma total triiodothyronine (T3) and free T3 (fT3) concentrations increased from 4 to 14 weeks of age in infants fed either formula, but decreased in breast-fed infants. At 9 and 14 weeks of age, infants fed the formulas averaged 31% higher T3 and 53% higher fT3 concentrations compared with breast-fed infants. Although T3 concentrations of the high P/S formula group compared with the low P/S formula group were not different at any single age, from 4 to 14 weeks the T3 averaged 19% higher in the high P/S formula group. Plasma total thyroxine (T4) or free T4 (fT4) concentrations were not significantly different among the diet groups during the preweaning period. In summary, formula-fed infants maintained higher plasma T3 and fT3 levels compared with breast-fed infants in the late preweaning period.
Reduced Levels of Alpha-1-Antitrypsin in Children Exposed to High Levels of Air Pollution
Authors: Dziegielewska K.M. , Guminska M. , Matthews N. , Saunders N.R. , Wilkinson G.
Published: October 2009

Health risks associated with environmental pollution, particularly in Eastern Europe, are a cause for concern. In order to gain some insight into the effects of exposure to high levels of air pollution particularly by heavy metals, we measured the concentration of nine plasma proteins in plasma samples from newborn babies and 5- to 6-year old children living in heavily polluted areas of Poland, as well as from some newborns and adults from unpolluted areas of Poland and control samples within the local Southampton population. The concentrations of all proteins measured were in or close to their expected range, with the exception of α1-antitrypsin (α1AT). The concentration of this protein was lower in both groups of Polish children from the polluted areas, particularly in the 5- to 6-year old group. These children were shown to be phenotypically normal. Since adult levels of α1AT are usually reached within 2 weeks postpartum, these findings raise the possibility that continued exposure to high levels of pollution may lead to reduced levels of α1AT in plasma; this may compound the impairment of lung function in children living in highly polluted areas.
Effects of Hypoxia on Phrenic Neurogram Response to Vagal and Somatic Stimulation in Newborn Rabbits
Authors: Trippenbach Teresa
Published: October 2009

Effects of 10% O2 on the response of the phrenic neurogram to vagal (VS) and saphenous stimulation (SS) were studied in anesthetized and artificially ventilated newborn (group 1: 1–3 days old, n = 13; group 2: 8–14 days old, n = 14) and adult (group 3, n = 12) rabbits. In all animals during ventilation with 100% O2 or 10% O2 in N2, VS caused a reduction in the expiratory phase (Te). Te shortening in response to SS was unaffected by hypoxia in group 3, and was abolished in group 2. In group 1 only early hypoxia blocked the Te response to SS. The preserved Te response to VS on one hand, and abolished the effects of SS on the other, suggest that blockade of the somatic inputs is due to the age-dependent action of hypoxia in areas distant to the respiratory neurons.
Hepatic Handling of an Oral Glucose Load in Suckling and Weaned Rats
Authors: Casado Javier , Snell Keith
Published: October 2009

Changes in the net balance of glucose and lactate across the intestine and liver have been studied in 15-day-old suckling and 25-day-old weaned rats over 60 min following an oral glucose load. The intestinal balance of suckling rats showed a net release of glucose that accounted for 80% of the oral load. By contrast, weaned animals showed a nil glucose balance. The hepatic balance of suckling rats switched rapidly from glucose output to glucose uptake following the oral glucose load, and this was associated with a net glycogen deposition. In weaned animals there was a net glucose release by the liver. The liver of 15-day-old suckling rats is able to extract glucose from the blood when circulating levels are raised under physiological circumstances, as well as the ability to synthesize glycogen.
Changes in Plasma Copper and Zinc during Rat Development
Authors: Martínez Lista E. , Solé J. , Arola L.I. , Mas A.
Published: October 2009

The association of copper and zinc to plasma ligands was studied during the rat perinatal period. Analysis was carried out by means of column chromatography (Sephadex G-150) and atomic absorption spectrophotometry. Levels of copper were low at birth and showed a sharp increase after day 10. This increase was similar to that of ceruloplasmin activity as well as its association with copper. Zinc levels, instead, showed higher levels before birth and decreased slowly toward the adult values. Association of zinc to albumin and associated proteins showed a pattern similar to the decrease in plasma zinc levels.
Gestational Age Correlates with Skin Reflectance in Newborn Infants of 24–42 Weeks Gestation
Authors: Lynn Cynthia J. , Saidi Iyad S. , Oelberg David G. , Jacques Steven L.
Published: October 2009

Accurate gestational age determination is limited in very low birthweight infants using neurological and physical assessments. As one of the markers of intrauterine development, skin maturation is assessed qualitatively by pediatricians. Based on this observation, we hypothesize that skin reflectance relates directly to gestational age. Light was delivered and collected from the skin through a topically placed optical patch. Reflected light was detected by the spectrophotometer and corrected by an adjacent laptop computer to yield the true total diffuse reflectance as a function of wavelength between 380-820 nm. The calculated reflectance at 837 nm (R837) where it is independent of melanin, was determined by extrapolation from the reflectance at 650 and 750 nm. Sixty-four neonates of different races with gestational ages of 24-42 weeks were studied at 2-151 h of age. R837 was related exponentially to gestational age (GA) by the equation R837 = Rmax{1 –– exp[––(GA –– G₀)/Τ]}, where Rmax is the maximal value of R837, G₀ is an apparent delay time before dermal scattering increases rapidly, and Τ is a time constant, r = 0.88, p < 0.001. In summary, the extrapolated skin reflectance offers a quantitative and objective assessment of gestational age which is independent of melanin and sex.
Measurement of Lumbar Spinal Bone Mineral Density in Preterm Infants by Dual-Energy X-Ray Absorptiometry
Authors: Tsukahara Hirokazu , Sudo Masakatsu , Umezaki Minoru , Fujii Yasushi , Kuriyama Masanori , Yamamoto Kazutaka , Ishii Yasushi
Published: October 2009

Lumbar spinal bone mineral density (BMD) was measured in 40 preterm infants by dual-energy X-ray absorptiometry (DXA). During the first several months of life, their BMD was considerably lower than that of normal term infants and the osteopenia was more pronounced in the more preterm and smaller infants. Weak (inverse) correlations were found between the BMD and urinary calcium/creatinine or tubular phosphorus reabsorption ratio. Rickets-like changes in the forearm bones did not predict the greater spinal osteopenia. Follow-up study was performed in 10 preterms. In 3 of the 4 who underwent the last DXA between 8 and 12 months, BMD had improved remarkably. Our present study shows the potential of DXA for the assessment and management of osteopenia of prematurity.
The Use of Intravenously Administered Immunoglobulins in the Prevention of Severe Infection in Very Low Birth Weight Neonates
Authors: van Overmeire B. , Bleyaert S. , van Reempts P.J. , van Acker K.J.
Published: October 2009

In a randomized prospective study in 116 selected neonates with very low birth weight, the effect of standard doses of intravenously administered immunoglobuiins (IVIG) on the occurrence of severe infections was studied. No difference in infection rate or severity of infection could be observed between the treated neonates and the control group. The lack of effect could not be explained by an insufficient increase in the IgG serum levels, or inversely, by high immunosuppressive IgG levels. It is concluded that in very low birth weight neonates the administration of IVIG, under the conditions used in this investigation, does not protect against severe infection.
Endocrine Regulation of Fetal Adipose Tissue Metabolism in the Pig: Role of Thyroxine
Authors: Hausman D.B. , Hausman G.J. , Martin R.J.
Published: October 2009

This study was performed to characterize the role of thyroxine (T4) in the regulation of fetal adipose tissue metabolism. On day 70 of gestation, pig fetuses were hypophysectomized (hypoxed) by microcauterization. Both hypoxed and intact fetuses were implanted subcutaneously with T4 pellets or received no hormone replacement. Fetuses were removed by laparotomy on day 90 of gestation. Additional fetuses were hypoxed on day 70, implanted with T4 pellets on day 90 and removed on day 105 of gestation. Serum T4 levels were similar in hypox + T4 and intact + T4 fetuses and increased in both groups relative to their respective controls. T4 supplementation restored the lipolytic response to isoproterenol and enhanced the response to dibutyryl cyclic AMP at 90 days in hypoxed animals but had no effect on basal or stimulated lipolysis in intact fetuses. T4 induced a dramatic increase in lipogenesis in hypoxed fetuses when administered during either fetal period and produced a slight though significant increase in basal lipogenesis in intact fetuses when administered from days 70 to 90 of gestation. However, T4 had no effect on basal or insulin-stimulated lipogenesis in intact fetuses when administered from days 90 to 105 of gestation. These results indicate that T4 may have a primary influence on fetal adipose tissue metabolism only in the absence of inhibition from counterregulatory hormones of pituitary origin.
Effect of Hypoxemia and Hypovolemia on Retinal and Choroidal Blood Flow in the Newborn Piglet
Authors: Odden J.P. , Bratlid D. , Hall C. , Farstad T. , Roll E. , Stiris T.
Published: October 2009

The effect of hypoxemia and/or hypovolemia on ocular blood flow was studied in paralyzed and mechanically ventilated newborn piglets with the isotopelabelled microsphere method. Twenty-six piglets were studied in four different groups. One group of piglets (n = 6) was made hypoxemic by breathing 10% O2, a second group (n = 7) and a third group (n = 7) were studied during hypoxemia (10% O2), followed by hypovolemia (bleeding 20 and 30% of estimated blood volume, respectively). A fourth group of piglets (n = 6) was made hypovolemic by bleeding 20% of estimated blood volume. Hypoxemia resulted in a 2- to 3-fold increase in retinal blood flow (RBF), while hypovolemia did not change RBF, not even when preceded by a period of hypoxemia. In the case of choroidal blood flow (ChBF), the increase caused by hypoxemia was only 10–40%. Although ChBF decreased significantly during hypovolemia, no significant correlation between mean arterial blood pressure and ChBF was found. The results indicate that autoregulation is normally seen in RBF, but probably not in ChBF. However, during hypoxemia autoregulation was found neither in RBF nor in ChBF.
Thyroidal Regulation of Lingual Lipase Development in Suckling Rats
Authors: Lee Ping-Cheung , Fu Chang Ling , Borysewicz Ryszard , Werlin Steven L.
Published: October 2009

Rat lingual lipase undergoes maturational increases during postnatal development. The role of thyroxine (T4) in the control of lingual lipase during development was evaluated. T4 given at an early suckling stage (starting day 4 or 5) moderately increased lingual lipase (20–30%) compared to age-matched controls. A similar dose of T4 given later (age > 2 weeks) was ineffective. The T4-sensitive period coincides with a time of low circulating T4, suggesting a role of T4 in modulating the development of lingual lipase in rat pups. Since simultaneous treatment with U486, a type II glucocorticoid receptor antagonist only partially blocked the T4 induction of lingual lipase, T4 appeared to have a direct action on the lingual gland. Pups of propylthiouracil (PTU)-treated dams (previously found to be hypothyroid) showed a delay in the maturation of lingual lipase compared to age-matched pups whose dam was not given PTU. Pups were most sensitive to PTU in the early suckling stage. PTU-induced delayed maturation of lingual lipase was a result of hypothyroidism, since T4 replacement when given early (at the age of 5 days) abolished most of the effect of PTU. When T4 was given later (at the age of 10 days), recovery was much less. This suggests the presence of an early period that is critically dependent on T4 for the full expression of lingual lipase in the rat tongue serous glands. In the same animals following various treatments, their pancreatic lipase and amylase were regulated by the thyroidal status as previously reported, i.e. hyperthyroid increased and hypothyroid decreased the enzyme levels. The magnitude of changes of pancreatic lipase as a result of hypo- or hyperthyroidism, however, was far greater than those observed with lingual lipase indicating a difference in tissue responsiveness to T4.
Resuscitation of the Very Immature Infant: Cerebral Doppler Flow Velocities in the First 20 Minutes of Life
Authors: Jorch Gerhard , Rabe Heike , Michel Erik , Engels Margret , Schulz Verena , Hentschel Roland , Koch Hans-Georg , Hultsch Ekhard
Published: October 2009

Blood flow velocity of the anterior cerebral artery was investigated by Doppler ultrasonography in five time intervals up to 20 min after birth in 16 non-asphyxiated very immature infants (median birth weight 1,058 g, range 720-1,930 g; median gestational age 30 weeks, range 27-32 weeks) delivered by caesarean section and intubated after birth. Heart frequency, oscillometric mean arterial blood pressure and blood gases were recorded as well. There was a transitory increase in both systolic and end-diastolic velocities (from 29 to 35 and from 1 to 10 cm/s) during the first 5 min after birth which occurred together with an increase in heart frequency. The overall incidence of intracranial haemorrhage was low (3/16, 19%). This observation study shows a transitory increase in cerebral blood flow velocity with a peak at about 5 min after birth in preterm infants < 33 weeks of gestation undergoing standard resuscitation.
The Neonatal Guinea Pig as a Model for Human Galactose Metabolism: Galactose-1-Phosphate Uridyltransferase Activity
Authors: Lundell Beverly I. , Savaiano Dennis A.
Published: October 2009

The specific activity of galactose-1-phosphate uridyltransferase was measured in fetal and neonatal guinea pig liver during the first 10 days of age. Activity was approximately six times greater than in adult animals, and peaked during the first 48 h after birth. Activity dropped sharply during the next 2 days, followed by a gradual decline. Liver galactose and glycogen levels were stable throughout the study period. Liver glucose rose significantly after birth, then dropped slightly. The pattern of uridyltransferase in the guinea pig is similar to that reported for phosphoenolpyruvate carboxylkinase and pyruvate carboxylase. Compared to the rat, specific activity of uridyltransferase peaked earlier, possibly due to the guinea pig’s advanced maturity.
Effect of Preclosure Colostrum Intake on the Development of the Intestinal Epithelium of Artificially Reared Piglets
Authors: Kelly D. , King T.P. , McFadyen M. , Coutts A.G.P.
Published: October 2009

Trophic factors in mammalian colostrum promote the growth of the small intestine of neonates. To investigate the effect of colostrum feeding on the expression of specific intestinal proteins, animals were reared in a minimal disease unit and fed either sow colostrum or a commercial substitute by gastric intubation at 3-hour intervals over the first 24 h of life. Animals were then reared on a commercial milk replacer and fed over a maximum period of 5 weeks. Intestinal protein, DNA and histology data suggested a positive effect of colostrum on intestinal growth in the initial postnatal period. At week 1 post partum intestinal lactase was found to decline significantly in colostrum-fed (CF) piglets compared to substitute-fed animals. This effect was no longer apparent at 3 and 5 weeks post partum. Sucrase activity was significantly greater in CF piglets and this effect was sustained during the 5 postpartum weeks studied. The changes in enzyme activity could be correlated with posttranslational sialylation of intestinal membranes. These result suggest that feeding colostrum enhances the maturational decline in lactase activity and the expression of sucrase activity. The role of glycosylation of enzyme proteins in relation to their biological activity is discussed.
Lipoprotein Lipase in Developing Rat Tissues: Differences between Wistar and Sprague-Dawley Rats
Authors: Galan Xavier , Llobera Miquel , Ramírez Ignasi
Published: October 2009

Lipoprotein lipase in animal tissues is known to be affected by fasting, but contradictory results have been published concerning this effect in particular tissues. For example, we reported that lipoprotein lipase activity expressed in the liver of neonatal rats was either increased or not affected by fasting. To evaluate the influence of the rat strain used as experimental animal model, we studied differences between Wistar and Sprague-Dawley rats in the development and in the effect of fasting on lipoprotein lipase and hepatic lipase activities in tissues of neonatal rats. Beside some minor differences in the development of lipoprotein lipase in some tissues like brown adipose tissue and lungs, we found quite remarkable differences between both strains in the development of lipoprotem lipase and hepatic lipase activities in the liver. In 1-day-old neonates, differences between both strains were also observed in the effect of fasting on lipoprotein lipase activity both in liver and lungs. In the liver of Wistar pups lipoprotein lipase activity was increased by fasting by 350%, but only by 50% in the liver of Sprague-Dawley pups. In contrast, in the lungs of Wistar pups lipoprotein lipase activity was increased by fasting by 280%, but by 580% in lungs of Sprague-Dawley rats. Therefore, our results indicate that quantitative differences exist between Wistar and Sprague-Dawley rats in the regulation of lipoprotein lipase.
Reversal of Lung Maturational Delay in the Fetus of the Diabetic Rat Using Triiodothyronine or Dexamethasone
Authors: Rotenberg Meir , Gewolb Ira H.
Published: October 2009

Administration of glucocorticoids and thyroid hormone can accelerate fetal lung development. To investigate whether the delayed fetal lung maturation seen in the diabetic rat gestation could be reversed by dexamethasone (DEX) or triiodothyronine (T3), control and streptozotocin-diabetic dams were injected daily from day 18 of gestation with either saline, 0.5 mg/kg DEX, or 1 mg/kg T3 until sacrifice on day 21 or day 22. While DEX did not change glucose levels in diabetic animals, T3 resulted in a slight reduction in both maternal (474 ± 25 vs. 539 ± 17 mg%; p < 0.07) and fetal (354 ± 43 vs. 404 ± 26 mg%; p < 0.05) serum glucose concentrations. DEX therapy exaggerated the reduction in body and lung weight seen in fetuses of streptozotocin-diabetic dams. Fetal lung phosphatidylcholine and disaturated phosphatidylcholine levels were significantly reduced in saline-treated diabetic animals as compared with controls. However, fetuses of T3- or DEX-treated diabetic rats had significantly increased lung phosphatidylcholine and disaturated phosphatidylcholine levels as compared with fetuses of untreated diabetic rats; these data suggest that maternal DEX or T3 therapy reverses the delayed fetal lung maturation seen in the diabetic rat gestation. Since glucocorticoids can exacerbate maternal diabetes, treatment with thyroid hormone may be more appropriate, although risks must be weighed against potential benefits.
Digestive Enzyme Development in Newborn Piglets Born of Sows Immunized against Somatostatin and/or Receiving Growth Hormone-Releasing Factor during Gestation
Authors: Farmer C. , Brazeau P. , Morisset J.
Published: October 2009

Thirty-eight second parity sows were either immunized (IMM) against somatostatin (SRIF) and/or injected with growth hormone-releasing factor (GRF) during gestation. Treatment effects on pancreatic, gastric and duodenal development as well as on digestive enzyme activity of piglets at birth (before suckling) or at 24 h postpartum were investigated. Birth weights of piglets were similar across treatments (p > 0.1). Weight, DNA, RNA, total protein content and enzyme activity for all three organs increased between birth and 24 h postpartum (p < 0.01), except for pancreatic RNA and chymotrypsin which decreased (p < 0.01), and protein content of the pancreas which was unaltered (p > 0.1). Gastric RNA, pancreatic weight DNA, RNA:DNA and amylase:DNA ratios were increased in 1-day-old piglets from SRIF-IMM sows (p < 0.05). GRF only had significant effects (p < 0.05) on the maltase:DNA ratio, which it decreased. Yet, there were tendencies (p < 0.1) for duodenal weight, DNA and total protein content to be increased in piglets from GRF-injected dams. It is therefore apparent that major developmental changes of the pancreas, stomach and duodenum of piglets take place during the first 24 h postpartum. Injections of GRF and/or immunization against SRIF during gestation in swine also have several effects on digestive enzyme activity of neonatal pigs. Yet, the physiological implications of these early changes are not clear at the present time.
Specific Developmental Profiles of Lysosomal and Brush Border Enzymuria in the Human
Authors: Simeoni U. , Schnitzler B. , Massfelder T. , Hirt C. , Koehl C. , Hamel G. , Helwig J.J. , Messer J. , Geisert J. , Willard D.
Published: October 2009

Various enzymatic urinary activities have been proposed to assess renal proximal tubule damage in children, including neonates. Nevertheless comprehensive knowledge on the developmental aspects of physiological enzymuria is limited, particularly with regard to lysosomal and brush border enzymuria. Urinary activities of two lysosomal enzymes, N-acetyl-β-D-glucosaminidase (NAG) and β-galactosidase (GAL), and of two brush border enzymes, alanine aminopeptidase (AAG) and γ-glutamyltransferase (GGT) were comparatively investigated in normal prematures (n = 28), term neonates (n = 52), infants aged less than 2 years (n = 19) and children (n = 33), and compared to urinary excretion of β2-microglobulin (B2M). Enzymatic activities were assayed using either spectrophotometrical (NAG, AAP, GGT) fluorimetrical (GAL) or radioimmunological (B2M) methods, and were related to urinary creatinine excretion. Developmental profiles of both the studied lysosomal enzymes and of B2M were similarly characterized with significantly decreasing values from prematures (NAG 9.29 ± 1.44, GAL 2.26 ± 0.26 IU/mmol creatinine, indicated as mean ± SEM) to term neonates (6,94 ± 0.58 and 1.76 ± 0.15 IU/ mmol creatinine, respectively) and older infants and children. Lysosomal enzymatic urinary activities correlated linearly with a coefficient of r = 0.75, (p < 0.05), while correlations between each lysosomal enzymatic activity and B2M urinary excretion were weaker. Profiles of both the studied brush border enzymes were characterized with lower activities in prematures (AAP 4.45 ± 0.44, GGT 5.52 ± 0.49 IU/mmol creatinine) than in term neonates (5.62 ± 0.92 and 9.1 ± 1.73 IU/mmol creatinine, respectively) or even in infants with respect to GGT (AAP 4.06 ± 0.72 and GGT 11.54 ± 1.71 IU/mmol creatinine), with a consecutive decrease of activities in older infants or children. It is concluded that lysosomal and brush border enzymuria follow different developmental profiles in the normal human. Studies involving enzymuria as a marker of tubular lesion should include the measurements of at least one lysosomal and one brush border enzymatic activity, and should be interpreted with reference to the respective, specific developmental profiles.
Diaphragmatic Activity and Ventilation in Preterm Infants
Authors: Reis Francisco J.C. , Cates Donald B. , Landriault Leanne V. , Rigatto Henrique
Published: October 2009

To determine the effects of sleep on diaphragmatic activity and ventilation we studied 10 preterm infants (birth weight 1,840 ± 50 g, gestational age 33 ± 0.6 weeks, and postnatal age 9.4 ± 1.4 days). We measured surface and esophageal diaphragmatic electromyograms (EMGdi). Ventilation was measured using a nasal flowmeter and a flow-through system. Diaphragmatic activity was analyzed for total phasic activity, expiratory phasic activity, the expiratory to total phasic activity ratio, and the presence of ‘tonic’activity. The latter was defined by the presence of electrical activity and the end of expiration. There was a decrease in the average total phasic activity (1.25 vs. 0.71 s, p = 0.001), expiratory phasic activity (0.67 vs. 0.21 s, p = 0.002), the expiratory to total phasic activity ratio (0.51:0.27 s, p = 0.001) and tonic activity (51 to 5%, p = 0.01) from quiet to REM sleep in the surface EMGdi. Similar changes were found in the esophageal EMGdi, except that tonic activity was rarely observed. In parallel with these changes in electrical activity of the diaphragm, minute ventilation and alveolar ventilation increased from quiet to REM sleep. This increase was primarily related to an increase in frequency with a negligible change in tidal volume. The increase in frequency was primarily due to shortening of inspiratory time. The findings that tonic activity recorded via surface electrodes decreased substantially from quiet to REM sleep and was not observed in the esophageal EMGdi suggests that this tonic activity may represent electrical activity of the postural muscles of the chest wall rather than the diaphragm.
Are Age-Related Differences in Response to Myocardial Ischemia and Cardioplegia pH Dependent?
Authors: Anderson S.A. , Carr L.J. , Schierling T.D. , Kost G.J.
Published: October 2009

Phosphorus-31 nuclear magnetic resonance and left ventricular pressure development (dP/dt) were used to test the hypothesis that age-related differences in myocardial functional recovery after ischemia and cold crystalloid cardioplegia (CCC) are the result of an inverse relationship between recovery and the decrease in intracellular pH (pHi) during ischemia. Neonatal (3-8 days) and adult rabbit hearts were Langendorff perfused using two protocols: (1) control – 30min perfusion, 30 min global ischemia, 2 h reperfusion; (2) CCC – the same except ischemia was initiated after a 4-min infusion of cold hyperkalemic solution. Analysis of variance and the Tukey test showed the following significant differences between the protocols (p < 0.05). CCC decreased inorganic phosphate (Pi) during ischemia in both age groups, but more in adult hearts, and decreased Pi during reperfusion in adult hearts. CCC increased pHi during ischemia and ATP during ischemia and reperfusion in both age groups but more in adult hearts. CCC increased dP/dt during reperfusion only in adult hearts. The results are consistent with the hypothesis.
Urea Removal by Hemofiltration and Hemodiafiltration
Authors: Gouyon J.B. , Petion A.M. , Huet F. , Lallemant C.
Published: October 2009

Continuous hemofiltration is usually regarded as a safe method for controlling fluid overload in neonates presenting acute renal failure. We considered that continuous hemodiafiltration with a hemofilter type especially designed for use in the neonatal period could improve urea removal as compared with hemofiltration. Continuous arteriovenous hemofiltration (CAVH) and hemodiafiltration (CAVHD) were consecutively performed on 7 anesthetized adult rabbits which were given an urea infusion. The hemofilter was a 800-cm2 polysulfone model (Amicon Minifilter Plus). Mean values for physiological and operational parameters were comparable during CAVH and CAVHD, i.e., mean blood pressure (69.6 ± 14.9 and 70 ± 13.1 mm Hg, respectively), arterial oncotic pressure (16.0 ± 2.4 and 16.0 ± 1.7 mm Hg), hematocrit (36.2 ± 5.8 and 36.7 ± 4.4%), protein plasma level (38.9 ± 7.0 and 39.0 ± 6.4 g/l), urea plasma level (20.6 ± 6.5 and 19.9 ± 7.0 mmol/l), plasma flow in the hemofilter (7.89 ± 8.48 and 7.12 ± 3.08 ml/min), and ultrafiltrate rate (1.17 ± 0.49 and 1.73 ± 0.78 ml/min). CAVHD allowed a significant increase in urea clearance (4.74 ± 4.51 ml/min) as compared with CAVH (1.23 ± 0.81 ml/min). These experimental results suggest that CAVHD usefulness should be assessed in neonates presenting acute renal failure.
Electrolyte Transport Responses to Secretagogues in Neonatal versus Adult Rabbit Jejunum
Authors: MacNaughton Wallace K. , Gall Grant
Published: October 2009

The ability of the neonatal and adult rabbit jejunum to respond to different exogenous stimuli of electrolyte transport was investigated in vitro. When mounted in Ussing chambers, jejunum from neonatal rabbits exhibited a higher basal short circuit current and lower potential difference compared to jejunum from adult rabbits. As a result, basal conductance was approximately 50% higher in the neonatal group. When the tissue was subjected to electrical field stimulation, neonatal jejunum was significantly less responsive to stimulation with respect to change in short circuit current, particularly at sub-maximal stimulus strength and stimulus duration. The neonatal jejunum was less responsive than adult jejunum to exogenous application of prostaglandin E2 and 5-hydroxytryptamine, and more responsive to histamine. There was no significant difference in the responses to carbachol, epinephrine, leukotriene D4 or platelet-activating factor. The neonatal rabbit jejunum exhibited a greater capacity to synthesize prostaglandin E2 and the peptidoleukotrienes, and had a higher tissue content of 5-hydroxytryptamine than the adult rabbit jejunum.
Effects of Two Protein Hydrolysates on Growth, Nitrogen Balance and Small Intestine Adaptation in Growing Rats
Authors: Cézard J.P. , Tran T.A. , Macry J. , Zarrabian S. , Roger L. , Bressolier P. , Julien R. , Mendy F. , Kahn J.M.
Published: October 2009

The effects of feeding 2 protein hydrolysates, one prepared by controlled pepsin and pancreatic protease (including elastase II) hydrolysis of milk proteins (PPPH) and the other a di- and tripeptide bacterial protease hydrolysate of bovine albumin (DTPH), on the growth, nitrogen balance and small intestine adaptation of growing rats were analyzed. Two groups of 3-week-old rats (8 rats/group) were fed the liquid diets ad libitum for 2 weeks. The diets had the same caloric, nitrogen, carbohydrate and lipid contents. The amino acid compositions fulfilled the needs of growing rats. The diets differed in the original proteins, the hydrolysis technique used and the molecular weights of the peptides. Nitrogen intakes were similar. Although there was no difference in weight gain, nitrogen balance was significantly higher in the rats fed the PPPH diet (day 4-day 6: PPPH, 60 ± 4%, DTPH, 25 ± 5%; day 12-day 15: PPPH, 58 ± 3%; DTPH, 30 ± 5%). The stool nitrogens were identical, suggesting improved nitrogen storage in the rats fed the PPPH diet. Small intestine adaptation showed that the rats on the PPPH diet had significantly more protein (mg) and DNA (μg) per 10 cm of the jejunum (PPPH, 25.6 ± 2, 393 ± 20; DTPH: 15.7 ± 2,258 ± 23) and sucrase-specific activity and per μg of DNA (PPPH, 133 ± 5.7, 9.7 ± 0.5; DTPH, 113 v 5, 7 ± 1). The N-aminopeptidase-specific activity was the same in both groups. These data show that PPPH leads to better nitrogen retention and small intestine adaptation in growing rats than does DTPH.
Diaphragmatic Activity and Ventilation in Preterm Infants
Authors: Reis Francisco J.C. , Cates Donald B. , Landriault Leanne V. , Rigatto Henrique
Published: October 2009

To determine the effects of inhaled CO2 and abdominal loading on diaphragmatic electromyography (EMGdi) and ventilation during sleep, we studied 10 preterm infants (birth weight 1,840 ± 50 g; gestational age 32 ± 0.6 weeks and postnatal age 10.4 ± 1.4 days). We measured surface and esophageal diaphragmatic activity. Ventilation was measured using a nasal flowmeter and a flow-through system. Diaphragmatic activity was analyzed for the duration of total phasic and expiratory activities, the expiratory to total phasic activity ratio and the presence of tonic activity (defined by the presence of electrical activity of the diaphragm at the end of expiration). With 3% CO2 in quiet and REM sleep, the intensity of EMGdi increased, but the duration of total phasic activity, the expiratory to total phasic activity ratio and tonic activity did not change. During quiet sleep with 3% CO2, ventilation increased (0.392 ± 0.028 to 0.616 ± 0.058 1/ min; p = 0.001) due to an increase in tidal volume and frequency. Similar changes occurred in REM sleep. Abdominal loading with sandbags increased the duration of total phasic activity (0.68–0.78 s; p = 0.03), expiratory phasic activity (0.21–0.32 s; p = 0.01), the expiratory to total phasic activity ratio (0.28–0.39; p = 0.03) and diaphragmatic tonic activity (20–60%; p = 0.04) as measured with surface electrodes in REM sleep. It also increased the expiratory to total phasic activity ratio and tonic activity, as measured with surface electrodes in quiet sleep. Abdominal loading did not alter ventilation or the structure of the average breath in either sleep state. These findings indicate that: (1) in healthy preterm infants, inhaled CO2 alters EMGdi and the structure of the average breath in a similar manner: the activity increases but timing and tonus are not changed, and (2) abdominal loading alters the structure of diaphragmatic activity as recorded by surface and esophageal electrodes with a significant increase in expiratory activity and tonus, but it does not alter the structure of the average breath.
An Infant with Pseudohypoaldosteronism Accompanied by Cholelithiasis
Authors: Hanaki Keiichi , Ohzeki Takehiko , Iitsuka Toshiyuki , Nagata Ikuo , Urashima Hirohumi , Tsukuda Toshinori , Nagaishi Jun-ichi , Shiraki Kazuo , Shimizu Norio , Kaibara Nobuaki
Published: October 2009

A case of an infant with very rare concurrence of pseudohypoaldosteronism and cholelithiasis is described. Aldosterone concentration was extremely high (64.6 nmol/l; normal 0.03–4.4 nmol/l) and fludrocortisone did not have favorable effects on hyperkalemia (7.4 mEq/l) and hyponatremia (124 mEq/l). A gallstone was found using ultrasonography at age 6 months, and it was extirpated surgically. The combination has not been reported previously. The study supports the previous hypothesis that cholelithiasis is found more often in infants with dehydration or electrolyte derangement.
Carotid Body Chemoreception: Mechanisms and Dynamic Protection against Apnea
Authors: Lahiri S.
Published: October 2009

A critical role of peripheral chemoreceptors in terminating apnea and in initiating normal breathing has been emphasized. Since these are the only organs which signal hypoxia, failure of its adequate development can contribute to the disease of respiratory failure in neonatal life. The failure may reside in any of the steps from initiation of O2 chemoreception involving respiratory and non-respiratory pigments, ion balance including H+ and Ca2+, neurotransmitter mechanisms and transduction.
Effect of Dopamine on Carotid Chemoreceptor Activity in Newborn Kittens
Authors: Bairam A. , Hannhart B. , Choné C. , Marchal F.
Published: October 2009

In newborn kittens, intravenous bolus injections of dopamine may be inhibitory or excitatory to the carotid chemosensory activity. In order to further identify the role of dopaminergic mechanisms on the chemosensory activity in the kitten, 10 anesthetized, paralyzed and artificially ventilated kittens aged from 1 to 21 days were studied. The activity of a few chemoafferent fibers from one carotid sinus nerve was recorded at three levels of FiO2 in N2, 21,8 and 100%, before and during a continuous dopamine infusion at a dose of 10 μg/kg/min. The immediate effect of dopamine usually was a transient inhibition of carotid chemosensory discharge. After 2 min of infusion, the activity had consistently increased from 4.5 ± 0.8 to 8.8 ± 1.4 impulses/s (mean ± SEM, p < 0.05) in normoxia. Dopamine also significantly increased the steady state chemosensory response to hypoxia from 24.6 ± 3.7 to 33.4 ± 5.3 impulses/s. Hence, continuous infusion of dopamine has a dual effect on carotid chemoreceptor activity: early inhibition followed by excitation. The excitatory effect enhances the response to hypoxia. These data suggest that the dual effect of dopamine on carotid chemosensory discharge may be related to dopamine concentration in the carotid body.
Mechanisms of Neuronal Survival during Hypoxia: ATP-Sensitive K+ Channels
Authors: Haddad Gabriel G. , Jiang Chun
Published: October 2009

There has been an explosion in our understanding of how nerve cells in mammals respond to O2 deprivation and what are the mechanisms involved in nerve cell injury or survival. This is due to the development of new approaches, techniques and the clinical importance of brain ischemia and hypoxia. Recently, we have focussed on some issues pertaining to brain hypoxia in the newborn and adult. We have demonstrated that during anoxia intracellular K+ decreases significantly in nerve cells and that this K+ efflux is mediated by K+ channels that are sensitive to ATP. We have preliminary evidence that the activation of these channels attenuates the anoxia-induced depolarization in medullary neurons and can play a role in cell survival during anoxia. Further, we have characterized the distribution of these receptors/channels complexes in the CNS of the rat and in an anoxia-resistant animal: the turtle. These channels are present mainly in the cortex, substantia nigra and the cerebellum. Whole cell recordings (dissociated cells) established that these channels are postsynaptic in nature in medullary neurons. Single-channel recordings from our laboratory and those of others have started to reveal the intricacies of the regulation of these channels in excitable cells in general and in nerve cells in particular.
Studies of Neuroregulators in the Brain Stem of SIDS
Authors: Kopp N. , Denoroy L. , Eymin C. , Gay N. , Richard F. , Awano K. , Gilly R. , Jordan D.
Published: October 2009

Some dysmaturity of neuroregulator neuronal systems may be responsible for brain stem disorders. These disorders may partly explain the mechanism of death in SIDS. The available data using microbiochemical assays, immunocytochemical techniques and autoradiographic methods seem to show anomalies of some monoaminergic and of some peptidergic systems, especially in the medulla oblongata. All these data need to be confirmed by further studies. It should be understood that one positive effect of such neuroanatomical study on SIDS is to gain ‘normative’ data on the human brain during development.
Pulmonary Reflexes and Control of Breathing during Development
Authors: Trippenbach Teresa
Published: October 2009

The potency of the Hering-Breuer inspiratory-inhibitory and expiratory-promoting reflexes decreases with maturation in mammals. The Hering-Breuer deflation reflex is present at birth and its power changes little during postnatal development. Already during the second day of life the airway defence reflex resembles that of the adult rabbits. In contrast, sensitivity of the pulmonary chemoreflex does not reach the adult level by the end of the first week of life in newborns of the same species. The time course of functional development of respiratory reflexes coincides with the maturity of different species at birth.
Mechanisms of Obstructive Sleep Apneas in Infants
Authors: Kahn A. , Groswasser J. , Sottiaux M. , Rebuffat E. , Franco P.
Published: October 2009

During sleep, infants with obstructive sleep apneas are characterised by snoring, laborious breathing, and profuse sweating. During wakefulness, they may have breath-holding spells, and during feeding, difficult breathing and swallowing coordination. Abnormal weight, difficult growth, and recurring ear infections may also develop. During sleep apneas, cinefiuoroscopy shows approximation of tongue and hypopharyngeal tissues, with an obliteration of the air space. The obstructed breaths occur mainly in REM, and light NREM sleep, associated with total short sleep time, and frequent arousals. Preterm infants, and term neonates are more prone to obstructive apneas than older healthy infants. Apneas are more frequently seen in boys and in case of excess in body weight. Obstructive apneas are frequently associated with upper airway anatomic abnormalities: malformations, soft tissue infiltration, and neurologic lesions impairing muscle contractions. Alterations of the autonomic nervous control may induce airways obstructions. Contributing factors include mucopolysaccharide storage disease, hypothyroidism, or Down’s syndrome. Superimposed factors may occur, such as nasal obstruction, secretions in the airways, or tissue edema. Pressure- and chemo-sensitive reflexes may also favor obstruction. Environmental factors also contribute to the development of sleep apneas: body position, neck flexion, sleep deprivation, or the effects of sedative drugs.
Drug-Induced Apnea
Authors: Boutroy Marie-Jeanne
Published: October 2009

Drugs have been in the past and will in the future still be liable to induce apnea in neonates, infants and older children. At these different stages of development, the child may be abnormally vulnerable to respiratory disorders and apnea, and doses of drugs, without any abnormal side effects in adult patients, can be harmful in younger subjects. Drugs responsible for apnea during development are numerous, but more than half of the problems are induced by sedatives and hypnotics, among which phenothiazines, barbiturates, benzodiazepines (included transplacentally acquired) and general anesthetics are a few. Other pharmacological families are apnea inducers in the neonatal period and childhood: analgesics and opioid narcotics, agents acting at the levels of neuromuscular function and autonomic ganglia, and cardiovascular agents. The pathogenesis of these apneas depends on the disturbance of any mechanism responsible for the respiratory activity: medullary centers and brain stem structures, afferent influx to CNS, sleep stages, upper airways, lungs and respiratory muscles. At key stages such as birth and infancy, drugs may emphasize the particular sensitivity of the mechanisms responsible for inducing apnea. This might explain unexpected respiratory disorders during development.
Effects of Respiratory Stimulants on Cerebral Metabolism and Blood Flow
Authors: Nehlig Astrid
Published: October 2009

The cerebral metabolic and circulatory effects of the two main classes of respiratory stimulants used in the apnea of the newborn and premature infant, i.e. methylxanthines and doxapram, have not been studied in great detail. In adult animals and humans, methylxanthines widely increase cerebral metabolic rates and simultaneously decrease cerebral blood flow levels. Thus, these compounds are able to reset the level of coupling between cerebral blood flow and energy metabolism inducing a relative hypoperfusion at a constant metabolic rate. In neonates, methylxanthines induce no change in cerebral blood flow as long as the drop in pCO2 related to drug administration is prevented. Information on doxapram effects on cerebral blood flow and metabolism is very scarse and limited to adult animals. Doxapram does not induce any change in cerebral energy metabolism and transiently decreases cerebral blood flow. In conclusion, it seems that the use of methylxanthines in apneic newborn infants fulfils a good margin of safety with respect to cerebral blood flow as long as no other pathology such as marked hypoxia or seizures is present. The use of doxapram also seems to stay in a good margin of safety in terms of cerebral blood flow and energy metabolism but many more studies are necessary to better understand the effects of this respiratory stimulant on cerebral functional activity.
Diaphragm Pacing: Clinical and Experimental Results
Authors: Brouillette Robert T. , Marzocchi Mirella
Published: October 2009

Over the last 26 years diaphragm pacing has been used in over 400 adults and 70 children to support ventilation and oxygenation. Diaphragm pacing can be useful for conditions in which the brain stem respiratory centers provide little or no stimulation to the respiratory muscles, i.e. central hypoventilation syndrome, Arnold-Chiari malformation/brain stem dysfunction, and high quadriplegia. Because the pacing systems are so portable, the greatest advantages accrue to those patients who require ventilatory support both while awake and asleep. Infants and children require tracheostomy to avoid upper airway obstruction and bilateral pacing to meet higher metabolic demands. The stimulus parameters most appropriate for pediatric patients have been characterized as low stimulus frequency, short inspiratory time, and moderate respiratory rate. Use of similar stimulus parameters in an immature animal model has resulted in preservation of diaphragmatic structure and function but transformation of the diaphragm from a mixed muscle to one with a uniform population of type 1 fatigue-resistant fibers (physiologic, histochemical, myosin isoform, and ultrastructural evidence). In 33 pediatric patients, representing 96 patient-years of use, there were 26 failures of the pacing systems requiring removal and/or replacement of the internal components. Mean time to failure was 56 months. Of our 36 patients who had diaphragm pacing systems implanted, 26 are alive and 22 are currently using the pacing systems. Two recent advances may further improve the long-term outcome of patients using diaphragm pacing. Smaller, better encapsulated receivers may improve system longevity and a new stimulus electrode may reduce the risk of diaphragmatic damage.