Competitive inhibition of amino acid transport in human preovulatory ovarian follicles.

Unlabelled: To date we have yet to examine whether amino acid (AA) transport in human ovarian follicles is affected by competitive inhibition. In contrast, transplacental transfer of AAs in late-gestation sheep is characterized by reciprocal competition. This phenomenon has been described by algebraic equations of umbilical uptake of AAs based on maternal arterial concentrations.

Changes in fetal mannose and other carbohydrates induced by a maternal insulin infusion in pregnant sheep.

Background: The importance of non-glucose carbohydrates, especially mannose and inositol, for normal development is increasingly recognized. Whether pregnancies complicated by abnormal glucose transfer to the fetus also affect the regulation of non-glucose carbohydrates is unknown. In pregnant sheep, maternal insulin infusions were used to reduce glucose supply to the fetus for both short (2-wk) and long (8-wk) durations to test the hypothesis that a maternal insulin infusion would suppress fetal mannose and inositol concentrations.

Review of studies in human pregnancy of uterine and umbilical blood flows.

Uterine and umbilical blood flow measurements are reviewed in terms of studies carried out in uncomplicated human pregnancies. The review includes the perspective of how those estimates of flow fit with current knowledge of human fetal O2 consumption and uterine O2 and glucose consumption. From the consideration of both the O2 data and the flow measurements, we conclude that the best estimates for mean umbilical blood flow at term range between 120 and 145 ml•min-1•(kg fetus)-1.

Umbilical uptakes and transplacental concentration ratios of amino acids in severe fetal growth restriction.

Background: This study examines the relationship between placental amino acid (AA) transport and fetal AA demand in an ovine fetal growth restriction (FGR) model in which placental underdevelopment induces fetal hypoxemia and hypoglycemia.

Methods: Umbilical uptakes of AA, oxygen, glucose, and lactate were measured near term in eight experimental ewes (FGR group) and in eight controls (C group).

Results: The FGR group demonstrated significantly reduced umbilical uptakes of oxygen, glucose, lactate, and 11 AAs per kg fetus.

Human breast milk sugars and polyols over the first 10 puerperium days.

Objective: The transition from colostrum to mature breast milk during early puerperium is associated with significant concentration changes of numerous compounds. However, it is not known whether the free sugars, aminohexoses, and polyols are affected. Therefore, in this study, we aimed to determine their concentrations in human colostrum and milk during the first 10 days postpartum.

Transplacental supply of mannose and inositol in uncomplicated pregnancies using stable isotopes.

Objective: The aim of this study was to determine relative contributions of transplacental flux vs. fetal production for inositol and mannose in normal term pregnancies.

Study Design: Seven term uncomplicated pregnancies undergoing cesarean section were infused with (13)C- and (2)H-labeled isotopes of glucose, inositol, and mannose until a steady state was achieved.

Placental TonEBP/NFAT5 osmolyte regulation in an ovine model of intrauterine growth restriction.

TonEBP/NFAT5 (the tonicity-responsive enhancer binding protein/nuclear factor of activated T cells) modulates cellular response to osmotic changes by accumulating inositol and sorbitol inside the cells. Our objective was to assess placental osmolytes, TonEBP/NFAT5 RNA and protein expression, and signaling molecules across gestation between control and intrauterine growth restriction (IUGR) ovine pregnancies. Pregnant sheep were placed in hyperthermic conditions to induce IUGR.

The tissue and plasma concentration of polyols and sugars in sheep intrauterine growth retardation.

In an ovine model of placental insufficiency-induced intrauterine growth retardation (PI-IUGR), characterized by hypoxia, hypoglycemia and a significant reduction in fetal weight, we assessed alterations in fetal and placental polyols. Arterial maternal-fetal concentration differences of glucose and mannose were greater in the PI-IUGR fetus; glucose: C (n = 7), 2.68 +/- 0.

Effect of antenatal betamethasone on maternal and fetal amino acid concentration.

Objective: To determine the concentration of amino acids in women receiving the first course of antenatal betamethasone and to evaluate the umbilical venous and arterial amino acid concentrations at the time of elective cesarean section after betamethasone administration.

Study Design: Blood samples were collected from 34 pregnant women at risk of premature delivery before and 24 and 48 hours after the first course of betamethasone. In addition, maternal and cord blood samples were collected in 13 women undergoing an elective cesarean section between 24 and 192 hours after betamethasone.

Determination of the NFAT5/TonEBP transcription factor in the human and ovine placenta.

Osmotic stress results in the accumulation of osmolytes in tissues. Synthesis of these osmolytes is mediated by the transcription factor NFAT5/TonEBP in the human kidney. We tested for the presence of NFAT5 mRNA and protein in the human and ovine placenta and confirmed sorbitol and inositol osmolyte concentrations in these tissues.

Inositol and mannose utilization rates in term and late-preterm infants exceed nutritional intakes.

Nonglucose carbohydrates such as mannose and inositol are important in early growth and development, although little is known about their metabolism. Our aim in this study was to determine the plasma appearance rates (Ra) for mannose and inositol in newborns as an index of utilization and as an improved guide to supplementation practices. We studied late-preterm (n = 9) and term (n = 5) infants (median 34 wk gestation, range 33-41 wk) using a multiple isotope infusion start time protocol to determine Ra for each carbohydrate.

Neonatal morbidity and mortality in intrauterine growth restricted (IUGR) pregnancies is predicated upon prenatal diagnosis of clinical severity.

The objective of this work was to determine whether the prenatal determinates of clinical severity in intrauterine growth restricted pregnancies, established by abdominal circumference measures, correlates with neonatal morbidity and mortality. A total of 336 singleton pregnancies with intrauterine growth restriction were subdivided into group 1 (normal fetal heart rate and pulsatility index of the umbilical artery: 251 cases), group 2 (normal fetal heart rate and abnormal pulsatility index: 50 cases), and group 3 (abnormal fetal heart rate and pulsatility index: 35 cases). Gestational age, birth weight, body mass index, placental weight, and Apgar score were significantly related to the severity of intrauterine growth restriction (P < .

Comparison of fetal and neonatal growth curves in detecting growth restriction.

Objective: To evaluate the outcome of intrauterine growth restriction (IUGR) infants with abnormal pulsatility index of the umbilical artery according to the neonatal birth weight/gestational age standards and the intrauterine growth charts.

Methods: We analyzed 53 pregnancies with severe IUGR classified as group 2 (22 IUGR: abnormal pulsatility index and normal fetal heart rate) and group 3 (31 IUGR: abnormal pulsatility index and fetal heart rate). Neonatal birth weight/gestational age distribution, body size measurements, maternal characteristics and obstetric outcome, and neonatal major and minor morbidity and mortality were compared with those obtained in 79 singleton pregnancies with normal fetal growth and pulsatility index, matched for gestational age (appropriate for gestational age [AGA] group).

The transplacental transport of essential amino acids in uncomplicated human pregnancies.

Objective: The purpose of this study was to assess the placental transport of the essential amino acids (EAAs) in normal pregnancies.

Study Design: Nine ((13)C or (2)H) EAAs were infused simultaneously as a bolus into the maternal circulation of 12 patients with uncomplicated pregnancy before cesarean delivery. Maternal samples were collected before and after the bolus; umbilical blood was collected at delivery.

Plasma concentrations of carbohydrates and sugar alcohols in term newborns after milk feeding.

Nonglucose carbohydrates such as galactose, mannose, and inositol play a clinically important role in fetal and neonatal nutrition, though little is known about their metabolism in the neonate. The aim of this study was to determine whether postprandial changes in plasma carbohydrate and sugar alcohol concentrations are affected by clinical variables such as postnatal age (PNA), milk type, feeding volume, or feeding duration in term newborns. Neonates (n = 26) taking intermittent enteral feedings were enrolled.

Concentrations of monosaccharides and their amino and alcohol derivatives in human preovulatory follicular fluid.

The study purpose was to compare sugar and polyol concentrations in preovulatory ovarian follicular fluid (FF) with those in the circulation. Samples of FF and peripheral venous blood were obtained after an overnight fast from 14 women attending an IVF program. High performance liquid chromatography measurements of seven polyols, two aminohexoses and four hexoses were the main outcome measures.

Placental transport: a function of permeability and perfusion.

Studies in ovine fetus and placenta have pointed to an interaction between the fetal liver and the placenta. The supply of amino acids and carbohydrates depends on this interaction. These studies have led to clinical studies in normal and high-risk pregnancies.

Amino acid, ammonia and urea concentrations in human pre-ovulatory ovarian follicular fluid.

Background: This study aimed to determine amino acid (AA), ammonia and urea concentrations in human ovarian follicular fluid and to compare these concentrations with those in the circulation.

Methods: Samples of pre-ovulatory follicular fluid and peripheral venous blood were obtained from 14 IVF patients. High-performance liquid chromatography (HPLC) measurements of 25 AAs were the main outcome measures.

Lactacidemia in intrauterine growth restricted (IUGR) pregnancies: relationship to clinical severity, oxygenation and placental weight.

The aim of the study was to evaluate the impact of clinical severity and placental weight upon fetal lactacidemia in intrauterine growth restricted (IUGR) pregnancies. Seventy pregnancies complicated by IUGR were compared with 70 normal (appropriate for gestational age, AGA) pregnancies at the time of elective cesarean section. IUGR pregnancies were divided according to clinical severity in three groups: Group 1 had normal fetal heart rate (FHR) and normal pulsatility index of the umbilical artery (PI); Group 2 had normal FHR and abnormal PI; and Group 3 had abnormal FHR and PI.

Free sugar and sugar alcohol concentrations in human breast milk.

Objectives: The goal was to determine the free sugars and polyols in human breast milk, both term and preterm, for comparison with formula milks.

Methods: Methodology was developed for the measurement of the free sugars and polyols in breast milk. There were 16 samples collected from women who delivered at term and 17 samples from women delivering preterm.

Fetal and maternal non-glucose carbohydrates and polyols concentrations in normal human pregnancies at term.

The objective of the present investigation was to determine fetal and maternal plasma concentrations of nonglucose carbohydrates and polyols in normal human pregnancies at term. Uncomplicated human pregnancies (n = 50) were studied at > or =37 wk gestation. Blood samples were obtained from umbilical artery, umbilical vein, and maternal peripheral blood at the time of elective cesarean section.

Polyol concentrations in the fluid compartments of the human conceptus during the first trimester of pregnancy: maintenance of redox potential in a low oxygen environment.

Polyols are sugar alcohols formed by the reduction of aldoses and ketoses. Production is favored under conditions of low oxygenation, when it may provide an alternative means to production of lactate for regulating the oxidation-reduction balance of pyridine nucleotides. Polyols also act as important organic osmolytes and as precursors of cell membrane components.

Maternal and fetal blood ammonia concentrations in normal term human pregnancies.

Background: The current evidence on the primary source of ammonia production in the human fetoplacental unit is potentially misleading.

Objective: The aim of the present investigation was to determine the concentration of ammonia in human maternal and fetal blood at birth and to compare them with published data in late gestation sheep.

Methods: In 12 normal human pregnancies, umbilical arterial and venous and maternal venous blood was sampled, and whole blood ammonia concentrations were measured.