The Supply of Citrate to the Sheep Fetus
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<i>In situ </i>placental perfusion has been used to study the role of the sheep placenta in fetal citrate metabolism. The perfusate citrate concentrations rose steadily to values higher than in fetal plasma. This rise was not influenced by intravenous administration of citrate to the ewe. Concentration and electropotential gradients indicate that transplacental passage is unlikely and the rise is probably due to placental synthesis. However, the quantity of citrate supplied to the fetus was calculated to be small compared with the fetal metabolic rate. Comparison with the guinea pig shows close similarity in fetal plasma concentrations and the amount of citrate formed per unit weight of fetus.Keywords:
Transplacental
Liposomes with different charge, size and lipid composition were injected i.v. into pregnant rats and rabbits and their uptake and transport across the placenta were studied. Results show that the placenta is very efficient in removing liposomes from the maternal circulation and that it takes up more liposomes per gram of tissue than the liver. Liposomes are degraded intracellularly in the placenta and the entrapped material is then transported across to the fetus as free molecules. Under the experimental conditions described in this article, no intact liposomes were found to be transported across the placenta. In comparison to the i.v. injection, infusion of liposomes into pregnant rabbits had greater effect on the localization of liposomal drug in the placenta and fetal blood. In summary, these results show that small unilamellar vesicles enhance delivery of drugs and nutrients to the placenta. They also suggest the possible danger of toxicity to the fetus if the expectant female is undergoing liposomal drug treatment.
Transplacental
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Transplacental
Fetal circulation
Clearance
Transferrin receptor
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The study of distribution of J125 labelled homologous alpha-fetoproteins (AFP) and heterologous antibodies (anti-AFP) in rats indicated some differences in the level of radioactivity of organs and tissues in animals, depending on age, especially in kidneys and large intestine. In normal pregnancy AFP passes through the placenta in both directions, but in rather less relative amounts from the fetus to mother. No labelled AFP was found in the amniotic fluid of fetuses 5 hours after its injection to pregnant mice. Anti-ATP injected in normal pregnant mice failed to pass through the placental barrier to the fetus, and radioactivity 5 hours following the injection was detected neither in fetal tissues nor in the amniotic fluid. After transplacental exposure of fetuses to methyl nitrosurea the labelled AFP was found in the amniotic fluid, while anti-AFP-both in fetal tissues and the amniotic fluid.
Transplacental
Heterologous
Alpha-fetoprotein
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Currently, information regarding isomer-specific concentrations of PFHxS, PFOS, and PFOA in human placenta, and corresponding placental-maternal ratios (RPM) of these compounds does not exist. The objective of the present study was to assess the occurrence, and distribution of different PFHxS, PFOS, and PFOA isomers in maternal serum, umbilical cord serum, and placenta to gain a better understanding of transplacental transport efficiency and prenatal exposure risks. The study involved quantitative determination of isomer-specific concentrations of PFHxS, PFOS, and PFOA in samples of maternal serum (n = 32), cord serum (n = 32), and placenta (n = 32) from pregnant women in Wuhan, China. The results indicate that both linear and branched PFHxS, PFOS and PFOA can be efficiently transported across the placenta, with exposure levels ordered maternal serum > cord serum > placenta. For PFOS isomers, the concentration ratios between cord serum and maternal serum (RCM) were ordered n < iso < 4m < (3 + 5)m < 1m < ∑m2. The RPM values exhibited a similar trend for branched PFOS isomers: iso < 4m ≈ (3 + 5)m < 1m ≈ ∑m2. Conversely, PFOA isomers did not exhibit an obvious structure–activity relationship for RCM and RPM. n-PFHxS transported across the placenta to a greater extent than br-PFHxS. To the best of our knowledge, this is the first study to report the occurrence of PFHxS, PFOS, and PFOA isomers in human placenta. Further, RPM values of these compounds are reported here for the first time. The findings help to better understand the mechanisms of the placental transfer and neonatal exposure to these important contaminants of concern.
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The fetal side of hemochorial placentas from guinea pigs between 58 and 62 days gestation were perfused in situ. Concurrent measurements were made of the clearances of radiocalcium and tritiated water from maternal to fetal circulation of the placenta, transplacental potential difference (TPD), maternal plasma and perfusate Ca, Na, and K concentrations, maternal blood pressure, gross permeability of albumin in the placenta, and net water movements. Movement of Ca from dam to fetus appeared to occur against an electrochemical gradient and was not associated with the movements of Na and K across the placenta. A negative correlation between perfusate Na and K concentrations, not dependent on maternal plasma Na and K concentrations and abolished by high concentrations of Ca in the fetal circulation of the placenta, strongly supports the concept of a Na-K exchange mechanism in the placenta directed so that K is moved against a concentration gradient towards the dam. There was no evidence that the TPD existed at the site of maternal-fetal exchange for Ca, Na, or K.
Transplacental
Placentation
Fetal circulation
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Effect of preparations from deer fetus and placenta on anti-aging of old male rats was studied. The results showed that the preparations from deer fetus and placenta inhibited MAO activities in brain and liver of rats significantly and decreased the contents of Lipofusin in heart and brain of rats. Deer fetus powder and deer fetus preparation Ⅱdecreased the MAO activities in brain by 67.74% and by 66.73% respectively, and the deer fetus preparation Ⅱdecreased the MAO activities in liver by 31.37%.It was concluded that the preparations from deer fetus and placenta have a good effect on anti-aging of old male rats, and the deer fetus preparation Ⅱ is more effective.
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Transplacental
Intravenous bolus
Bolus (digestion)
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The transplacental passage of monomethylphtalate (mMP) and mono (2-ethylhexyl) phthalate (mEHP) was studied using an ex vivo placental perfusion model with simultaneous perfusion of fetal and maternal circulation in a single cotyledon. Umbilical cord blood and placental tissue collected both before and after perfusion were also analyzed. Placentas were obtained immediately after elective cesarean section and dually perfused in a recirculation system. mMP or mEHP was added to maternal perfusion medium to obtain concentrations at 10 and 25 μg/L, respectively. The placental transfer was followed analyzing samples from fetal and maternal perfusion media by liquid chromatography–mass spectrometry–mass spectrometry (LC-MS-MS). Four perfusions with mMP indicated a slow transplacental transfer, with a fetomaternal ratio (FM ratio) of 0.30 ± 0.03 after 150 min of perfusion. Four perfusions with mEHP indicated a very slow or nonexisting placental transfer. mEHP was only detected in fetal perfusion media from two perfusions, giving rise to FM ratios of 0.088 and 0.20 after 150 min of perfusion. Detectable levels of mMP, mEHP, monoethylphthalate (mEP), and monobutylphthalate were found in tissue. Higher tissue levels of mMP after perfusions with mMP compared to perfusions with mEHP suggest an accumulation of mMP during perfusion. No tendency for accumulation of mEHP was observed during perfusions with mEHP compared to perfusions with mMP. Detectable levels of mEHP and mEP were found in umbilical cord plasma samples. mMP and possibly other short-chained phthalate monoesters in maternal blood can cross the placenta by slow transfer, whereas the results indicate no placental transfer of mEHP. Further studies are recommended.
Transplacental
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The study of distribution of J125 labelled homologous alpha-fetoproteins (AFP) and heterologous antibodies (anti-AFP) in rats indicated some differences in the level of radioactivity of organs and tissues in animals, depending on age, especially in kidneys and large intestine. In normal pregnancy AFP passes through the placenta in both directions, but in rather less relative amounts from the fetus to mother. No labelled AFP was found in the amniotic fluid of fetuses 5 hours after its injection to pregnant mice. Anti-ATP injected in normal pregnant mice failed to pass through the placental barrier to the fetus, and radioactivity 5 hours following the injection was detected neither in fetal tissues nor in the amniotic fluid. After transplacental exposure of fetuses to methyl nitrosurea the labelled AFP was found in the amniotic fluid, while anti-AFP-both in fetal tissues and the amniotic fluid.
Transplacental
Heterologous
Alpha-fetoprotein
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The environment in which the fetus develops is critical for its survival and long-term health. The regulation of normal human fetal growth involves many multidirectional interactions between the mother, placenta, and fetus. The mother supplies nutrients and oxygen to the fetus via the placenta. The fetus influences the provision of maternal nutrients via the placental production of hormones that regulate maternal metabolism. The placenta is the site of exchange between mother and fetus and regulates fetal growth via the production and metabolism of growth-regulating hormones such as IGFs and glucocorticoids. Adequate trophoblast invasion in early pregnancy and increased uteroplacental blood flow ensure sufficient growth of the uterus, placenta, and fetus. The placenta may respond to fetal endocrine signals to increase transport of maternal nutrients by growth of the placenta, by activation of transport systems, and by production of placental hormones to influence maternal physiology and even behavior. There are consequences of poor fetal growth both in the short term and long term, in the form of increased mortality and morbidity. Endocrine regulation of fetal growth involves interactions between the mother, placenta, and fetus, and these effects may program long-term physiology.
Trophoblast
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