The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Aydin Tekay - One of the best experts on this subject based on the ideXlab platform.
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antenatal diagnosis of fetal intra abdominal Umbilical Vein dilatation
Ultrasound in Obstetrics & Gynecology, 2001Co-Authors: Federico Prefumo, Aydin Tekay, Baskaran ThilaganathanAbstract:Dilatation of the intra-abdominal portion of the fetal Umbilical Vein is a rare abnormality. We describe here a new case diagnosed at 31 weeks of gestation and discuss the clinical features and management of this abnormality.
H Versmold - One of the best experts on this subject based on the ideXlab platform.
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Locally Released Norepinephrine in the Oxygen-Dependent Regulation of Vascular Tone of Human Umbilical Vein
Pediatric Research, 2004Co-Authors: Eva Mildenberger, G Siegel, H VersmoldAbstract:In a previous study, human Umbilical Vein preparations constricted at Po_2 values above the physiologic intrauterine Po_2 range and dilated at hypoxia. Denudation of the endothelium reversed the hypoxic vasodilatation only, suggesting the release of a nonendothelial vasoconstrictor. We therefore hypothesized that norepinephrine from adrenergic nerve terminals could be responsible for the observed constricting effects. We measured intracellular membrane potential and isometric tension of human Umbilical Vein strips with and without functional adrenergic denervation by 6-OH-dopamine during variation of Po_2. With Po_2 increasing from 5 to 104 mm Hg, intact preparations depolarized of from −58.6 ± 1.1 mV (SEM) to −53.3 ± 1.0 mV ( p < 0.001) and isometric tension increased from 0.673 ± 0.037 g to 0.825 ± 0.044 g ( p < 0.02). Intact preparations pretreated with 6-OH-dopamine depolarized from −58.0 ± 0.5 mV to −55.8 ± 0.6 mV ( p < 0.01), and isometric tension increased from 0.598 ± 0.040 g to 0.661 ± 0.018 g ( p < 0.02). At Po_2 values above the physiologic intrauterine Umbilical venous Po_2 range, membrane potential and isometric tension were significantly lower in preparations with 6-OH-dopamine pretreatment compared with matched controls ( p < 0.05). Denudation of the endothelium reversed the hypoxic hyperpolarization and vasodilatation observed in intact preparations. However, membrane potential and isometric tension were not different between endothelium-denuded preparations with and without 6-OH-dopamine pretreatment. We conclude that locally released norepinephrine contributes to the depolarization and vasoconstriction of the human Umbilical Vein at hyperoxia but does not antagonize the endothelium-dependent vasodilation at hypoxia.
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prostanoids contribute to the oxygen dependent regulation of vascular tone of human Umbilical Vein
Journal of Perinatal Medicine, 2004Co-Authors: Eva Mildenberger, G Siegel, H VersmoldAbstract:Aim: To investigate the contribution of prostanoids to the oxygen-dependent regulation of human Umbilical Vein vascular tone. Methods: Intracellular membrane potential and isometric tension of intact and endothelium-denuded human Umbilical Vein strips with and without cyclooxygenase inhibition by indomethacin (10 -5 M) were recorded simultaneously during variation of the local pO 2 . Results: Decreasing pO 2 from 39 to 5 mm Hg resulted in hyperpolarization and decrease in isometric tension of intact preparations. These effects did not occur in indomethacin treated preparations. Endothelium-denuded preparations revealed pronounced depolarization and increase in tension with decreasing pO 2 . Indomethacin treatment abolished these effects. With increasing pO 2 from 39 to 104 mm Hg intact preparations depolarized and isometric tension remained stable. Removal of the endothelium or treatment with indomethacin reversed these effects. Conclusions: This study confirms that the human Umbilical Vein actively regulates its vascular tone which is under the control of pO 2 . Vasodilating endothelial prostanoids contribute to the hypoxic vasodilatation and thereby counteract the vasoconstricting actions of prostanoids released from vascular smooth muscle cells. Our results indicate that vasoconstricting prostanoids are released from the endothelium of the human Umbilical Vein at hyperoxia.
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nitric oxide and endothelin in oxygen dependent regulation of vascular tone of human Umbilical Vein
American Journal of Physiology-heart and Circulatory Physiology, 2003Co-Authors: Eva Mildenberger, G Siegel, Beatrix Biesel, H VersmoldAbstract:We investigated the possible contribution of nitric oxide (NO) and endothelin (ET) to oxygen-dependent regulation of human Umbilical Vein vascular tone by simultaneous registration of intracellular...
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oxygen dependent regulation of membrane potential and vascular tone of human Umbilical Vein
American Journal of Obstetrics and Gynecology, 1999Co-Authors: Eva Mildenberger, G Siegel, H VersmoldAbstract:Abstract Objective: We question the hypothesis that vascular tone of human Umbilical Vein is insensitive to oxygen pressure and minimal already at resting conditions. Study Design: Isometric tension and intracellular membrane potential of native (n = 7) and endothelium-denuded (n = 7) human Umbilical Vein strips were recorded simultaneously at oxygen pressure values of 5 to 104 mm Hg. Results: Increasing oxygen pressure from 5 to 104 mm Hg led to graded membrane depolarization from –58.2 ± 1.3 mV (SEM) to –54.0 ± 0.7 mV ( P P r 2 = 0.99). Disruption of the endothelium reversed the effects of oxygen pressure. Conclusion: Human Umbilical Vein vascular tone was regulated by oxygen tension and showed a hypoxic vasodilator reserve. Oxygen-dependent effects were related to the membrane potential and required the endothelium. (Am J Obstet Gynecol 1999;181:696-700.)
Henry L. Galan - One of the best experts on this subject based on the ideXlab platform.
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early and persistent reduction in Umbilical Vein blood flow in the growth restricted fetus a longitudinal study
American Journal of Obstetrics and Gynecology, 2001Co-Authors: Serena Rigano, Maddalena Bozzo, Maria Bellotti, Elena Ferrazzi, Frederick C. Battaglia, Henry L. GalanAbstract:Abstract Objective: We have previously shown, in a cross-sectional study, that the reduction in Umbilical Vein blood flow in intrauterine growth-restricted fetuses is due to reduced Umbilical Vein velocity. The purpose of this longitudinal study in intrauterine growth-restricted fetuses was to determine whether the Umbilical Vein velocity reduction, which, in turn, reduces blood flow, persists throughout gestation or represents a late event that precedes indicated delivery. Study Design: Twenty-one intrauterine growth-restricted fetuses with an abnormal Umbilical artery velocimetry underwent serial sonographic and Doppler examinations from 23 to 36 weeks of gestation. Umbilical Vein diameter and velocity were measured, and Umbilical Vein absolute (milliliters per minute) and weight-specific blood flow (milliliters per minute per kilogram) were calculated. Umbilical Vein diameter, velocity, and blood flow were expressed per abdominal circumference. Intrauterine growth-restricted findings were compared to local reference data. Results: Intrauterine growth-restricted fetuses showed persistent reductions in Umbilical Vein blood flow per abdominal circumference and weight-specific blood flow (milliliters per minute per kilogram) from the time of diagnosis of intrauterine growth-restriction. Umbilical Vein velocity was reduced in the intrauterine growth-restricted fetuses, although Umbilical Vein diameter did not change. Conclusion: Reduction of Umbilical Vein blood flow is an early finding in intrauterine growth-restricted fetuses, and it can persist for several weeks until delivery. This reduction in blood flow is due to reduced Umbilical Vein velocity. (Am J Obstet Gynecol 2001;185: 834-8.)
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relationship of Umbilical Vein blood flow to growth parameters in the human fetus
American Journal of Obstetrics and Gynecology, 1999Co-Authors: Antonio Barbera, Serena Rigano, Henry L. Galan, Elena Ferrazzi, Frederick C. Battaglia, Maciej Jozwik, Giorgio PardiAbstract:Abstract Objective: Our purposes were to determine the relationship of the growth of Umbilical blood flow to growth in body measurements of human fetuses in uncomplicated pregnancies. The study also aimed to assess the relative contributions of growth in Umbilical Vein diameter and of increased velocity to the increase in Umbilical blood flow. Study Design: An animal study was conducted to assess the accuracy of Umbilical Vein blood flow measurements obtained by triplex mode ultrasonography. Seven pregnant ewes underwent triplex mode Umbilical Vein flow determination. These results were compared with historical flow data obtained by a steady-state diffusion technique in 34 ewes matched for gestational age and weight. In a separate study performed on human beings, reproducibility and precision of triplex mode flow determination were assessed, as were the relationships between Umbilical Vein flow and gestational age and head and abdominal circumferences. This cross-sectional study was performed with 70 healthy fetuses ranging from 20 weeks' gestation to term. Best-fit interpolating equations and confidence limits were calculated for blood flow measurements versus gestational age and head and abdominal circumferences. Results: In the validation study performed on sheep there were no significant differences between triplex mode and steady-state measurement groups with respect to gestational age or weight. The Umbilical Vein flows were similar between triplex mode and steady-state measurement groups ( P = .881). In the human study the intraobserver and interobserver coefficients of variation for the Vein diameter, mean velocity, and absolute Umbilical Vein blood flow varied from 2.9% to 12.7%. The mean duration of examination was 3 ± 1 minutes. The Umbilical Vein diameter and mean velocity increased throughout pregnancy. The absolute Umbilical Vein flow increased exponentially from 97.3 mL/min at midgestation to 529.1 mL/min at 38 weeks' gestation, whereas Umbilical Vein flow per kilogram of fetal weight did not change significantly with gestational age. There was a strong correlation between absolute Umbilical Vein flow and the fetal head and abdominal circumferences. Conclusions: The triplex mode ultrasonographic technique can play an innovative role in obtaining quick and reproducible measurements of Umbilical Vein blood flow. The approach was validated with a sheep model. Umbilical Vein blood normalized for fetal weight (milliliters per minute per kilogram of fetal weight) and absolute flow (in milliliters per minute) are consistent with previous human studies. We have established new reference values of Umbilical Vein blood flow relative to head and abdominal circumferences. The growth of Umbilical venous diameter accounted for most of the growth in Umbilical Vein flow. (Am J Obstet Gynecol 1999;181:174-9.)
Eva Mildenberger - One of the best experts on this subject based on the ideXlab platform.
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Locally Released Norepinephrine in the Oxygen-Dependent Regulation of Vascular Tone of Human Umbilical Vein
Pediatric Research, 2004Co-Authors: Eva Mildenberger, G Siegel, H VersmoldAbstract:In a previous study, human Umbilical Vein preparations constricted at Po_2 values above the physiologic intrauterine Po_2 range and dilated at hypoxia. Denudation of the endothelium reversed the hypoxic vasodilatation only, suggesting the release of a nonendothelial vasoconstrictor. We therefore hypothesized that norepinephrine from adrenergic nerve terminals could be responsible for the observed constricting effects. We measured intracellular membrane potential and isometric tension of human Umbilical Vein strips with and without functional adrenergic denervation by 6-OH-dopamine during variation of Po_2. With Po_2 increasing from 5 to 104 mm Hg, intact preparations depolarized of from −58.6 ± 1.1 mV (SEM) to −53.3 ± 1.0 mV ( p < 0.001) and isometric tension increased from 0.673 ± 0.037 g to 0.825 ± 0.044 g ( p < 0.02). Intact preparations pretreated with 6-OH-dopamine depolarized from −58.0 ± 0.5 mV to −55.8 ± 0.6 mV ( p < 0.01), and isometric tension increased from 0.598 ± 0.040 g to 0.661 ± 0.018 g ( p < 0.02). At Po_2 values above the physiologic intrauterine Umbilical venous Po_2 range, membrane potential and isometric tension were significantly lower in preparations with 6-OH-dopamine pretreatment compared with matched controls ( p < 0.05). Denudation of the endothelium reversed the hypoxic hyperpolarization and vasodilatation observed in intact preparations. However, membrane potential and isometric tension were not different between endothelium-denuded preparations with and without 6-OH-dopamine pretreatment. We conclude that locally released norepinephrine contributes to the depolarization and vasoconstriction of the human Umbilical Vein at hyperoxia but does not antagonize the endothelium-dependent vasodilation at hypoxia.
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prostanoids contribute to the oxygen dependent regulation of vascular tone of human Umbilical Vein
Journal of Perinatal Medicine, 2004Co-Authors: Eva Mildenberger, G Siegel, H VersmoldAbstract:Aim: To investigate the contribution of prostanoids to the oxygen-dependent regulation of human Umbilical Vein vascular tone. Methods: Intracellular membrane potential and isometric tension of intact and endothelium-denuded human Umbilical Vein strips with and without cyclooxygenase inhibition by indomethacin (10 -5 M) were recorded simultaneously during variation of the local pO 2 . Results: Decreasing pO 2 from 39 to 5 mm Hg resulted in hyperpolarization and decrease in isometric tension of intact preparations. These effects did not occur in indomethacin treated preparations. Endothelium-denuded preparations revealed pronounced depolarization and increase in tension with decreasing pO 2 . Indomethacin treatment abolished these effects. With increasing pO 2 from 39 to 104 mm Hg intact preparations depolarized and isometric tension remained stable. Removal of the endothelium or treatment with indomethacin reversed these effects. Conclusions: This study confirms that the human Umbilical Vein actively regulates its vascular tone which is under the control of pO 2 . Vasodilating endothelial prostanoids contribute to the hypoxic vasodilatation and thereby counteract the vasoconstricting actions of prostanoids released from vascular smooth muscle cells. Our results indicate that vasoconstricting prostanoids are released from the endothelium of the human Umbilical Vein at hyperoxia.
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nitric oxide and endothelin in oxygen dependent regulation of vascular tone of human Umbilical Vein
American Journal of Physiology-heart and Circulatory Physiology, 2003Co-Authors: Eva Mildenberger, G Siegel, Beatrix Biesel, H VersmoldAbstract:We investigated the possible contribution of nitric oxide (NO) and endothelin (ET) to oxygen-dependent regulation of human Umbilical Vein vascular tone by simultaneous registration of intracellular...
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oxygen dependent regulation of membrane potential and vascular tone of human Umbilical Vein
American Journal of Obstetrics and Gynecology, 1999Co-Authors: Eva Mildenberger, G Siegel, H VersmoldAbstract:Abstract Objective: We question the hypothesis that vascular tone of human Umbilical Vein is insensitive to oxygen pressure and minimal already at resting conditions. Study Design: Isometric tension and intracellular membrane potential of native (n = 7) and endothelium-denuded (n = 7) human Umbilical Vein strips were recorded simultaneously at oxygen pressure values of 5 to 104 mm Hg. Results: Increasing oxygen pressure from 5 to 104 mm Hg led to graded membrane depolarization from –58.2 ± 1.3 mV (SEM) to –54.0 ± 0.7 mV ( P P r 2 = 0.99). Disruption of the endothelium reversed the effects of oxygen pressure. Conclusion: Human Umbilical Vein vascular tone was regulated by oxygen tension and showed a hypoxic vasodilator reserve. Oxygen-dependent effects were related to the membrane potential and required the endothelium. (Am J Obstet Gynecol 1999;181:696-700.)
Mary Munn - One of the best experts on this subject based on the ideXlab platform.
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pregnancy outcome after ultrasound diagnosis of fetal intra abdominal Umbilical Vein varix
Ultrasound in Obstetrics & Gynecology, 2009Co-Authors: Benjamin D Byers, Nima Goharkhay, Julio Mateus, K K Ward, Mary MunnAbstract:Objectives Fetal intra-abdominal Umbilical Vein (FIUV) varix is a focal dilatation of the intra-abdominal portion of the Umbilical Vein, which has been reported to be associated with intrauterine death and other anomalies. Our aim was to examine our experience with this diagnosis at a single tertiary-care center and to correlate it with clinical outcome. Methods This was a retrospective case series study. Our ultrasound database was searched for all cases with a diagnosis of FIUV varix identified at our facility between 1997 and 2007. We reviewed all ultrasound examinations, maternal antenatal records, delivery records and newborns’ medical records. Results We identified 52 cases of FIUV among a population of approximately 68 000. Three cases of trisomy 21 were identified, all of which were accompanied by other anomalies. There was intrauterine death of one fetus with trisomy 21 at 35 weeks of gestation. We did not find an association between FIUV varix and other obstetric complications. Conclusions The outcome of pregnancies with FIUV varix is generally favorable. The finding of a FIUV varix should prompt the search for other anomalies, especially markers of aneuploidy. Copyright 2008 ISUOG. Published by John Wiley & Sons, Ltd.
