bluuebunny/crossref_metadata_2025_split huggingface dataset:
Developmental Regulation of the Inhibitory Effect of Dopamine on Prolactin Release in the Preterm Neonate
Authors: Seri Istvan , Somogyvari Zsolt , Hovanyovszky Sarolta , Kiszel Janos , Tulassay Tivadar 
Published: April 2003

The secretion and release of prolactin from the anterior pituitary is under the tonic inhibitory control of endogenous dopamine produced in the central nervous system. Exogenous dopamine inhibits prolactin secretion by reaching the pituitary via the portal circulation, and the hypolactotropic effect of dopamine infusion has been documented in all age groups in humans. However, the maturation of lactotroph sensitivity to dopaminergic inhibition has not been studied. Therefore, we followed the changes in serum prolactin concentrations before, during, and after dopamine infusion in 19 sick preterm infants with a mean gestational age of 30.6 ± 0.6 weeks during the first 3 days of life, and examined the relationship of the hypolactotropic effect of dopamine to gestational age and birth weight in this patient population. As expected, dopamine therapy resulted in a decrease in mean serum prolactin from 89.4 ± 9.5 to 58.6 ± 9.1 µg/l (p < 0.05) with a return of the serum prolactin concentration to the pretreatment level 2–6 h after discontinuation of drug administration (98.3 ± 11.7 µg/l, p < 0.05). However, simple regression analysis of the individual data revealed that the magnitude of the dopamine-induced decrease in serum prolactin was significantly influenced by gestational age (p = 0.006) and birthweight (p = 0.037). Thus, our findings provide evidence for the maturation of pituitary lactotroph sensitivity to dopaminergic inhibition in the preterm human neonate.
Effect of Dietary n–3 Fatty Acids on Hypoxia-Induced Necrotizing Enterocolitis in Young Mice
Authors: Akisü Mete , Baka Meral , Çoker Işıl , Kültürsay Nilgün , Hüseyinov Afig 
Published: April 2003

Necrotizing entercolitis (NEC) is an important neonatal disease with a high mortality rate. Inflammatory mediators, such as mainly platelet-activating factor (PAF), leukotrienes (LT) and tumor necrosis factor play an important role in the genesis of NEC. Diets in Ω–3 (n–3) fatty acids appear to have an antiinflammatory effect, which is thought to be due to decreased active prostaglandins and leukotrienes production after incorporation of these fatty acids into cell membrane phospholipids. We investigated the protective effect of fish oil (source of n–3 fatty acids) on hypoxia-induced model of NEC. Young mice were divided into three groups; group 1 mice were fed standard chow (n–3 fatty acids-free), group 2 was fed a chow supplemented by 10% fish oil for 4 weeks. Group 3 mice served as control. We examined the intestinal lesions by light microscopy and measured intestinal tissue PAF and LB<sub>4</sub> levels in hypoxia-induced model of NEC. Significantly increased intestinal PAF and LTB<sub>4</sub> levels were found in group 1 mice when compared to group 2 and group 3 mice. The histopathology of the intestinal lesions in group 1 animals was characteristic of ischemic injury. In the n–3 fatty acids-supplemented animals these lesions were milder. The present study shows that endogenously released PAF and LTB<sub>4</sub> play an important role in mediating hypoxia-induced intestinal necrosis. The present study also suggests that dietary supplementation with n–3 fatty acids suppress intestinal PAF and LTB<sub>4</sub> generation in hypoxia-induced bowel necrosis. The intestinal protective effect of n–3 fatty acids in an experimental model of NEC may open new insight into the treatment and preventation of NEC in neonates.
Pharmacodynamic Effects and Pharmacokinetic Profile of Continuous Infusion Fentanyl in Newborn Piglets
Authors: Rajan Vigna , Beharry Kay D.A. , Williams Paul , Modanlou Houchang D. 
Published: April 2003

The objective of this study was to determine hemodynamic effects and pharmacokinetic profiles of fentanyl with continuous infusion in 1- to 3-day-old newborn piglets. The piglets (n = 6) were administered a loading dose of fentanyl at 30 µg/kg i.v. over 15 min followed by a continuous i.v. infusion at 10 µg/kg/h for 6 h. The control group (n = 8) received equivalent volume bolus and infusion of 5% dextrose. Blood samples were obtained serially from systemic circulation and sagittal sinus vein for measurement of plasma fentanyl, pH and blood gases. Plasma fentanyl achieved steady state levels by 30 min of infusion both in the systemic (202.7 ± 39.1 ng/ml) and sagittal sinus vein (136.7 ± 20.7 ng/ml). Fentanyl caused a transient increase in respiratory rate at 2 h. Heart rate was significantly elevated at 30 min and 6 h during infusion but systemic and sagittal sinus vein blood pressure remained unchanged. Systemic and sagittal sinus vein PO<sub>2</sub> were significantly decreased from 2 through 6 h of infusion. Compared to the control group, there was a 56% (p < 0.01) decrease in sagittal sinus vein O<sub>2</sub> content at 30 min of infusion, an effect which lasted up to 6 h (47%, p < 0.01). Fractional O<sub>2</sub> extraction by the brain increased significantly at 30 min (26%, p < 0.01) and remained elevated throughout the infusion time (22%, p < 0.05 at 6 h). Brain fractional O<sub>2</sub> extraction increased as a function of brain fractional fentanyl extraction (r<sup>2</sup> = 0.40, p < 0.001). Mean clearance was estimated as 56.2 ± 13.7 ml/kg/h (range 43.5–76.9 ml/kg/h), mean volume of distribution at steady state was 1.29 ± 0.6 liters/kg (range 0.78–2.15 liters/kg) and the mean half-life was 15.7 ± 5.7 h (range 9.4–22.5 h). These data suggest that increased systemic oxygen may be necessary to maintain normal cerebral oxygen extraction during fentanyl anesthesia/analgesia.
Maturational Modification of Hypoxic Relaxation in Ovine Carotid and Cerebral Arteries: Role of Endothelium
Authors: Zurcher Shelley D. , Ong-Veloso Gleen L. , Akopov Sergey E. , Pearce William J. 
Published: April 2003

In light of evidence that hypoxia inhibits cerebrovascular calcium influx and that the contractile importance of calcium influx is greater in neonatal than adult cerebral arteries, the present studies evaluate the hypothesis that the mechanisms involved in hypoxic cerebral vasodilation are different in newborn and adult cerebral arteries. Intact segments of ovine common carotid (COM) and middle cerebral (MCA) arteries from 3- to 7-day-old newborn lambs and nonpregnant adults were mounted in tissue baths, contracted with 1 µ<i>M</i> 5-HT, and exposed to hypoxia for 20 min (P<sub>O2</sub> ≈ 12 Torr). In endothelium-intact arteries, the magnitude of relaxation was similar and near maximal in all groups (range 82–92%) and did not vary with either age or artery type. However, the magnitude of hypoxic relaxation after endothelium removal was attenuated more in adult (COM 37 ± 6%, MCA 53 ± 7%) than in newborn (COM 75 ± 5%, MCA 93 ± 1%) arteries. In addition, endothelium-dependent responses to A23187, which like hypoxia increases endothelial cell concentrations of calcium, were attenuated in immature compared to mature arteries. Reductions of extracellular calcium concentration from 1.6 to 0.8 m<i>M</i> eliminated all age-dependent differences in relaxation responses to hypoxia. Together these data demonstrate that in newborn arteries, the endothelium-dependent component of hypoxic vasodilation is minimal, especially in intracerebral arteries, and robust relaxant responses to hypoxia depend on the high sensitivity of immature smooth muscle cells to decreases in P<sub>O2</sub>. In contrast, in adult arteries the smooth muscle sensitivity to decreases in P<sub>O2</sub> is minimal and the endothelial component of hypoxic relaxation is particularly important in responses to hypoxia.
Effect of Deferoxamine on Post-Hypoxic-Ischemic Reperfusion Injury of the Newborn Lamb Heart
Authors: Shadid Majidah , van Bel Frank , Steendijk Paul , Dorrepaal Caroline A. , Moison Ralph , van der Velde Enno T. , Baan Jan 
Published: April 2003

Post-hypoxic-ischemic (HI) reperfusion induces excess production of non-protein-bound iron (NPBI), leading to formation of the highly reactive hydroxyl radical. We investigated whether the iron-chelator deferoxamine (DFO) could reduce reperfusion injury and improve left ventricular (LV) function. We produced severe HI in 14 newborn lambs and measured pre-HI, upon reperfusion, 60 and 120 min after HI the following parameters: mean aortic blood pressure, total peripheral resistance, stroke volume (SV), ejection fraction (EF) and LV contractility (pre-HI, 60 and 120 min post-HI). These parameters were assessed by measuring LV pressure (tip manometer) and volume (conductance catheter), using inflow occlusion to obtain slope (E<sub>es</sub>) and volume intercept of the end-systolic P-V relationship (V<sub>10</sub>). We determined the antioxidative capacity, i.e. the ratio of ascorbic acid and dehydroascorbic acid (AA/DHAA) and malondialdehyde from coronary sinus blood at pre-HI and at 15, 60 and 120 min post-HI. Seven lambs received DFO (10 mg/kg i.v.) immediately after HI, 6 control lambs received a placebo. While neither E<sub>es</sub> nor EF changed significantly in either group, the volume intercept V<sub>10</sub> in the DFO-treated group was significantly smaller (0.25 ± 0.03 vs. 0.70 ± 0.09, p < 0.05), whereas SV was larger (3.6 ± 0.6 vs. 2.2 ± 0.2 ml, p < 0.05) and the AA/DHAA ratio was significantly lower at 15 min post-HI (p < 0.05) providing evidence for HI damage and for the protective effect of DFO. In conclusion: post-HI treatment of the newborn lamb with DFO has a modifying effect on free radical-induced damage to the myocardium and protects myocardial performance.
Gender Difference in Cord Serum Ferritin Concentrations
Authors: Tamura T. , Hou J. , Goldenberg R.L. , Johnston K.E. , Cliver S.P. 
Published: April 2003

We measured cord serum ferritin concentrations in a total of 255 infants (116 females and 139 males), and evaluated the association between these values and various neonatal as well as maternal characteristics. The mean ferritin concentration in females (166 ± 110 μg/l) was significantly higher than that in male infants (123 ± 77 μg/l). The gender differences in ferritin were significant within groups of infants with fetal growth restriction, those who weighed <3,000 g, those whose mothers were African Americans or <25 years old. Maternal serum ferritin concentrations at 36 weeks of gestation significantly correlated with cord serum ferritin of male infants (r = 0.32, p < 0.001), whereas the association was not significant for females (r = 0.09, p > 0.41). Although the mechanism of the gender difference is unknown, it may be important to consider the sex of neonates when evaluating their iron nutriture immediately after birth.
The Effects of Dimethyl Sulfoxide on Renal Function of the Newborn Rabbit
Authors: Rijtema Mariette , Mosig Dolores , Drukker Alfred , Guignard Jean-Pierre 
Published: April 2003

The purpose of this study was to establish the effects of intravenous dimethyl sulfoxide (DMSO), a solvent used in a wide variety of products (medicines), on kidney function in the newborn rabbit. Three groups of anesthetized, ventilated, normoxemic 4- to 8-day-old New Zealand White rabbits received a 90-min intravenous infusion of DMSO at a dose of 1.11 (group 1), 16.5 (group 2) or 111 μg/ kg/h (group 3). The only change observed in the animals of group 1 was a significant increase in filtration fraction (FF; p < 0.001), whereas no change at all was observed in the renal functional parameters of the animals of group 2. The highest dose of DMSO (group 3), however, caused a very significant (p < 0.001) decrease in renal blood flow (RBF) and a rise in renal vascular resistance (RVR), FF and urine volume (UV). Glomerular filtration rate (GFR) and systemic parameters such as pH, mean arterial blood pressure and heart rate did not change. The rise in GFR, RVR, UV (group 3 vs. 2) and FF (groups 3 vs. 2 and 2 vs. 1) was dose-dependent. No significant dose-dependent decrease in RBF was found. To the best of our knowledge, there are no previous reports on the effect of DMSO on renal function in the solvent doses used in this study. We ascribe the reported effects to the ‘immaturity’ of the newborn rabbit kidney. Consequently, this agent should be used with great caution in developmental studies.
Effects of Inhaled Nitric Oxide and High-Frequency Ventilation in Rabbits with Meconium Aspiration
Authors: Huang Qi-Wei , Sun Bo , Gao Feng , Zhang Yu-Ming , Wu Yue , Zhu Lie Wei , Lindwall Robert 
Published: April 2003

Aim: To evaluate effects of inhaled nitric oxide (iNO) in experimental meconium aspiration treated with high-frequency (HFV) or conventional mechanical ventilation (CMV). Ventilated adult rabbits had meconium instilled intratracheally resulting in respiratory failure as evidenced by more than 50% reduction of dynamic lung compliance (Cdyn) and increase in mean oxygenation index (OI) from 1 to 16. The animals were then allocated to 2 groups treated without (control) or with iNO at 20 ppm (NO). In each group the animals were initially ventilated with CMV or HFV mode for 3 h and then in a crossover fashion with HFV or CMV for another 3 h (CMV→HFV, HFV→CMV), respectively. In the first 3 h of treatment, the animals subjected to HFV-CMV in the control, and those with both HFV-CMV and CMV-HFV in the NO group had significantly reduced OI. In the subsequent 3 h, the animals in the control group with CMV-HFV did not improve in OI and those with HFV-CMV had deteriorated. In the NO group with both CMV-HFV and HFV-CMV moderate improvement of OI was observed. Platelet aggregation capability and counts were significantly decreased and bleeding time prolonged in animals receiving iNO treatment. These results suggest that both HFV alone and a combined treatment of iNO with either CMV or HFV are more effective in improving blood oxygenation than that of CMV in this animal model. The influence of iNO on platelet aggregation should be considered.
The Role of Bradykinin in Neonatal Hemodynamic Effects of ACE Inhibition
Authors: Tóth-Heyn Péter , Thonney Viani Michèle , Guignard Jean-Pierre 
Published: April 2003

Angiotensin-converting enzyme (ACE) inhibitors exert their effects by inhibiting angiotensin II (AII) production, but also by inhibiting bradykinin (BK) degradation. In order to clarify whether BK is involved in the systemic effects of ACE inhibition in the newborn period, we investigated the effect of perindoprilat (20 μg/kg i.v.) in newborn rabbits, with or without the blockade of BK β<sub>2</sub>-receptors (Hoe 140, 300 μg/kg s.c.). The bolus infusion of perindoprilat resulted in a marked fall in mean arterial blood pressure (MBP) and a slight decrease in heart rate. BK receptor blockade had no effect on the perindoprilat-induced hypotension but the negative chronotropic effect of ACE inhibition was partly prevented by pretreatment with Hoe 140. We therefore conclude that BK is not involved in neonatal blood pressure regulation but that the ACE inhibition-induced neonatal bradycardia is at least partly BK- mediated.
Prophylactic Treatment of Endotoxic Shock with Monophosphoryl Lipid A in Newborn Rats
Authors: Wy Cherry Ann , Goto Masakatsu , Young Rita I. , Myers Thomas F. , Muraskas Jonathan 
Published: April 2003

Mortality due to gram-negative septic shock remains high despite advances in medical care. Induction of endotoxin tolerance might be a new treatment strategy to prevent septic shock in the newborn. The present study was performed to show that an injection in pregnant rats of monophosphoryl lipid A (MPL), a nontoxic derivative of lipopolysaccharide (LPS), induces tolerance to <i>Salmonella enteritidis</i> LPS and tumor necrosis factor alpha (TNF-α) in their offspring. MPL at a dose of 2 mg/kg was injected into pregnant rats on the 19th day of gestation. Their 0-day-old offspring later received an intraperitoneal injection of <i>S. enteritidis</i> LPS or TNF-α. Newborn rats of MPL-treated dams exhibited a higher survival rate, absence of lactacidemia and lower plasma TNF-α concentration in response to <i>S. enteritidis</i> LPS when compared to the newborn rats of saline-treated dams. Newborn rats of MPL-treated dams were more tolerant to TNF-α than those of saline-treated dams. MPL injection into pregnant rats did not increase plasma endotoxin concentration in the fetuses, suggesting no placental passage took place, but it did increase plasma TNF-α concentration. We concluded that an injection of MPL into pregnant rats induced tolerance to LPS in their offspring, which might be due to TNF-α-induced TNF-α tolerance.
Paroxysmal Vagal Overactivity, Apparent Life-Threatening Event and Sudden Infant Death
Authors: Lucet V. , de Bethmann O. , Denjoy I. 
Published: April 2003

The possibility of reversible cardiac asystoly due to paroxysmal vagal overactivity (VO) has been well studied, first in adults, then in children, and finally in breath-holding spells. Few studies deal with infants and the incidence of VO among preterm, apparent life-threatening event (ALTE) and sudden infant death syndrome (SIDS). In this review, we summarize data acquired during the past 20 years leading to the diagnosis of VO in infants. We describe the clinical aspects of VO in infants and young children such as Holter-ECG and oculocardiac reflex criteria. The familial aspect of VO and its possible link with SIDS (a new risk factor?) are discussed. Finally, whether or not to treat infants with symptomatic VO is discussed.
Effect of Follicle-Stimulating Hormone on Sertoli Cell Division in Cultures of Fetal Rat Testes
Authors: Sasaki Motoki , Yamamoto Masako , Arishima Kazuyoshi , Eguchi Yasunobu 
Published: April 2003

The present study was performed to determine when follicle-stimulating hormone (FSH) begins to promote Sertoli cell division in fetal rats, and to determine whether the effect of FSH is mediated by cAMP-dependent protein kinase (PKA). When testes from 15- to 17-day fetuses were cultured with or without FSH for 48 h, FSH did not promote Sertoli cell division in 15-day testes, but did in 16- and 17-day testes. Anti-rat FSH was injected into 16-day fetuses in utero. Twenty-four hours later, the testes of the injected fetuses and those of their intact littermates were cultured with or without FSH for 48 h. Without FSH, the Sertoli cell division index was significantly lower in anti-FSH-treated fetuses than in intact fetuses. With FSH, however, the index increased. When PKA inhibitor was added to cultures of 16-day testes with FSH, the promotion of Sertoli cell division by FSH was inhibited. We conclude that between 16 and 17 days of gestation, fetal pituitary FSH stimulates the division of Sertoli cells by activating the PKA activity.
Effects of Feeding Colostrum and a Formula with Nutrient Contents as Colostrum on Metabolic and Endocrine Traits in Neonatal Calves
Authors: Rauprich A.B.E. , Hammon H.M. , Blum J.W. 
Published: April 2003

Colostrum provides high amounts of nutrients and non-nutrient substances to neonates. To study differences between effects of nutritional and non-nutritional components on growth, health status and metabolic and endocrine traits, a formula was created based on bovine milk components which contained similar amounts of nutrients as bovine colostrum during the first 3 days of lactation, but only trace amounts of growth factors (such as insulin-like growth factor I) or hormones (such as insulin) in whey. Calves were fed either pooled colostrum of milkings 1 to 6, obtained during the first 3 days of lactation (GrC, n = 7) or a formula in the same amounts as colostrum (GrF, n = 7) for the first 3 days, followed by a milk replacer up to day 7. Pre- and postprandial blood samples were taken on days 1, 2, 3 and 7 for the determination of metabolic and endocrine traits and on day 5 we measured intestinal absorptive capacity by testing xylose absorption. Plasma concentrations of total protein and immunoglobulin G and γ-glutamyltransferase activity were lower (p < 0.05), whereas albumin and urea concentrations were higher (p < 0.05) in GrF than GrC during the first week of life. Plasma glucose concentrations were variably affected. Plasma triglyceride, phospholipid and cholesterol concentrations were higher (p < 0.05) in GrC than GrF on days 3 and 7. Insulin and growth hormone concentrations were higher (p < 0.05) in GrC than GrF on days 2 and 3 and on days 1 and 2, respectively, and glucagon concentrations were higher (p < 0.05) in GrC than GrF on day 1 and higher (p < 0.05) in GrF than GrC on day 3. Cortisol concentrations were higher (p < 0.05) on days 2 and 3 in GrF than GrC. Plasma xylose concentrations rose more markedly (p < 0.05) in GrC than GrF. In conclusion, feeding only trace amounts of bioactive substances appears to impair intestinal absorptive capacity and protein and fat metabolism and exert effects on endocrine systems in neonatal calves.
Placental Transfer of Pyrimethamine Studied in an ex vivo Placental Perfusion Model
Authors: Peytavin Gilles , Leng Jean-Joël , Forestier François , Saux Marie-Claude , Hohlfeld Patrick , Farinotti Robert 
Published: April 2003

Pyrimethamine is used as and anti-infectious agent because of its antifolate properties. Its action is synergistic with that of dapsone and sulfamides on <i>Toxoplasma gondii</i>. The goal of the present study was to evaluate the placental transfer of pyrimethamine in an ex vivo model of perfused human placental cotyledon at term. Human placentas were perfused according to the slightly modified method of Schneider. The pyrimethamine fetal transfer rate was approximately 30%, while cotyledon clearance was about 1.8 ml/min. The placental transfer of pyrimethamine seems to be independent of the maternal concentrations of pyrimethamine, suggesting passive diffusion mechanisms or a nonsaturable active transport at the tested concentrations.
The Effect of Interleukin-12 and Interleukin-15 on CD69 Expression of T-Lymphocytes and Natural Killer Cells from Umbilical Cord Blood
Authors: Lin Syh-Jae , Chao Hsun-Chin , Kuo Ming-Ling 
Published: April 2003

We investigated the effect of two immunoregulatory cytokines interleukin-12 (IL-12) and IL-15, alone or in combination, on CD69 expression of mononuclear cells (MNCs) obtained from umbilical cord blood (CB) and adult peripheral blood (APB). We established that (1) CD3/69, but not CD16/69, expression on CB MNCs could be increased with IL-12, IL-15 or both in 18-hour cultures, but to a lesser degree compared to that on corresponding APB MNCs, (2) CD3/69 expression on CB MNCs was significantly increased after 1 week’s culture with IL-12, especially with IL-15, exceeding that on APB MNCs similarly activated and (3) CD16/69 expression on CB MNCs, but not APB MNCs, was greatly increased after 1 week’s culture with IL-15. The combination of IL-12 + IL-15 resulted in greater CB CD3/69 expression than individual cytokines, while producing less of an effect on CD16/CD69 expression as compared to IL-15 alone. The results of our study indicate that neonatal T and NK cells readily respond to cytokine stimulation by upregulating CD69 expression, with a greater effect achieved using IL-15 compared to IL-12.