Mechanisms of drug transfer across the human placenta

Prenatal exposure to emerging and traditional organophosphate flame retardants: Regional comparison, transplacental transfer, and birth outcomes

During gestation, organophosphate flame retardants (OPFRs) have the potential to pose health risks to fetuses due to their ability to cross the placental barrier. However, data are scarce regarding the transplacental transfer of these compounds, particularly concerning emerging OPFRs and regional variations. In this study, we analyzed 14 traditional OPFRs and 5 emerging OPFRs in maternal and cord serum samples from Mianyang and Hangzhou, two cities in eastern and western China, respectively. The results revealed marked disparities in the overall levels of OPFRs between the two cities (p < 0.05), with the average concentration in maternal serum being higher in Hangzhou (14.55 ng/mL) than in Mianyang (8.28 ng/mL). The most abundant compounds found in both cities were tris (2-chloroethyl) phosphate (TCEP), Triphenyl phosphate (TPHP), and Tri-n-butyl phosphate (TnBP). Additionally, this study marked the first detection of novel OPFRs, including resorcinol bis (diphenyl phosphate) (RDP), isodecyl diphenyl phosphate (IDDPP), cresyl diphenyl phosphate (CDP), and bisphenol A bis (diphenyl phosphate) (BPA-BDPP) in maternal and cord serum simultaneously with the detection frequencies higher than 45%. This study also found that transplacental transfer efficiencies for OPFRs varied by ester group, with Aryl-OPFRs exhibiting the highest transfer rates (0.90-1.11) and Alkyl-OPFRs exhibiting the lowest (0.66-0.83). Transfer efficiencies exhibited a positive correlation with log Kow values (p < 0.05), suggesting that hydrophobic OPFRs with higher log Kow values are more likely to permeate the placental barrier. Moreover, the exposure levels of Tris (1,3-dichloro-2-propyl) phosphate (TDCIPP), Tri (Chloropropyl) Phosphate (TCIPP), TPHP, and CDP in cord serum were negatively associated (p < 0.05) with birthweight of newborns. This research adds to our understanding of the transplacental transfer of OPFRs and the possible health risks associated with prenatal exposure.

Transplacental passage of hyperforin, hypericin, and valerenic acid

Safe medications for mild mental diseases in pregnancy are needed. Phytomedicines from St. John’s wort and valerian are valid candidates, but safety data in pregnancy are lacking. The transplacental transport of hyperforin and hypericin (from St. John’s wort), and valerenic acid (from valerian) was evaluated using the ex vivo cotyledon perfusion model (4 h perfusions, term placentae) and, in part, the in vitro Transwell assay with BeWo b30 cells. Antipyrine was used for comparison in both models. U(H)PLC-MS/MS bioanalytical methods were developed to quantify the compounds. Perfusion data obtained with term placentae showed that only minor amounts of hyperforin passed into the fetal circuit, while hypericin did not cross the placental barrier and valerenic acid equilibrated between the maternal and fetal compartments. None of the investigated compounds affected metabolic, functional, and histopathological parameters of the placenta during the perfusion experiments. Data from the Transwell model suggested that valerenic acid does not cross the placental cell layer. Taken together, our data suggest that throughout the pregnancy the potential fetal exposure to hypericin and hyperforin – but not to valerenic acid – is likely to be minimal.

Placental Passage of Protopine in an Ex Vivo Human Perfusion System

The placental passage of protopine was investigated with a human ex vivo placental perfusion model. The model was first validated with diazepam and citalopram, 2 compounds known to cross the placental barrier, and antipyrine as a positive control. All compounds were quantified by partially validated U(H)PLC-MS/MS bioanalytical methods. Protopine was transferred from the maternal to the fetal circuit, with a steady-state reached after 90 min. The study compound did not affect placental viability or functionality, as glucose consumption, lactate production, and beta-human chorionic gonadotropin, and leptin release remained constant. Histopathological evaluation of all placental specimens showed unremarkable, age-appropriate parenchymal maturation with no pathologic findings.

First Evidence of Prenatal Exposure to Emerging Poly- and Perfluoroalkyl Substances Associated with E-Waste Dismantling: Chemical Structure-Based Placental Transfer and Health Risks

Limited information is available about prenatal exposure to per- and polyfluoroalkyl substances (PFAS) in electronic waste (e-waste) recycling sites. In this study, we determined 21 emerging PFAS and 13 legacy PFAS in 94 paired maternal and cord serum samples collected from an e-waste dismantling site in Southern China. We found 6:2 fluorotelomer sulfonate (6:2 FTSA), 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA), and perfluorooctanephosphonate (PFOPA) as the major emerging PFAS, regardless of matrices, at median concentrations of 2.40, 1.78, and 0.69 ng/mL, respectively, in maternal serum samples, and 2.30, 0.73, and 0.72 ng/mL, respectively, in cord serum samples. Our results provide evidence that e-waste dismantling activities contribute to human exposure to 6:2 FTSA, 6:2 Cl-PFESA, and PFOPA. The trans-placental transfer efficiencies of emerging PFAS (0.42-0.94) were higher than that of perfluorooctanesulfonic acid (0.37) and were structure-dependent. The substitution of fluorine with chlorine or hydrogen and/or hydrophilic functional groups may alter trans-placental transfer efficiencies. Multiple linear regression analysis indicated significant associations between maternal serum concentrations of emerging PFAS and maternal clinical parameters, especially liver function and erythrocyte-related biomarkers. This study provides new insights into prenatal exposure to multiple PFAS in e-waste dismantling areas and the prevalence of emerging PFAS in people living near the sites.

Placental transfer of bisphenol diglycidyl ethers (BDGEs) and its association with maternal health in a population in South of China

Despite high production and usage, little is known about exposure to bisphenol diglycidyl ethers (BDGEs) and their derivatives in pregnant women and fetuses. In this study, we determined nine BDGEs in 106 paired maternal and cord serum samples collected from e-waste dismantling sites in South of China. Bisphenol A bis (2,3-dihydroxypropyl) glycidyl ether (BADGE·2H2O), bisphenol A (3-chloro-2-hydroxypropyl) (2,3-dihydroxypropyl) glycidyl ether (BADGE·HCl·H2O), and bisphenol F diglycidyl ether (BFDGE) were the major BDGEs, with median concentrations of 0.57, 4.07, and 1.60 ng/mL, respectively, in maternal serum, and of 3.58, 5.61, and 0.61 ng/mL, respectively, in cord serum. The transplacental transfer efficiencies (TTEs) were estimated for BDGEs found in samples, and median values were in the range of 0.98 (BFDGE) to 5.91 (BADGE·2H2O). Our results suggested that passive diffusion plays a role in the placental transfer of BADGE·HCl·H2O and BFDGE, whereas several mechanisms contribute to the high accumulation of BADGE·2H2O in cord serum. Multiple linear regression analysis indicated significant associations between maternal serum concentrations of BDGEs and blood clinical biomarkers, especially those related to liver injuries, such as alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and adenosine deaminase (ADA) (P < 0.05). To our knowledge, this is the first study to report the occurrence of BDGEs in paired maternal-fetal serum samples and provide new insights into prenatal and fetal exposures. The newly discovered TTEs in maternal-fetal pairs contribute to a fuller inventory of the transmission activity of pollutants in the human body, ultimately adding to a more significant comprehensive risk evaluation.

Association between parabens concentrations in human amniotic fluid and the offspring birth size: A Sub-study of the PERSIAN birth cohort

OBJECTIVE

Parabens are extensively used, and cause widespread exposure of the general population including pregnant women and developing fetuses to these pollutants. In this study, we aimed to investigate the association between the maternal exposure of parabens to study their transfer passed through the placental barrier to amniotic fluid; the second objective was to determine the association of paraben concentration in the amniotic fluid with the offspring birth size.

METHODS

This cross-sectional study was conducted from June 2019 to March 2021 in Isfahan, Iran. Samples of amniotic fluid were collected as set from 128 pregnant women at Cesarean section. The amniotic fluid concentrations of four parabens including methylparaben (MP), ethylparaben (EP), propylparaben (PP), and butylparaben (BP) were determined using gas chromatography tandem mass spectroscopy (GC-Mass).

RESULTS

The pointed parabens were extracted from yielded clear supernatant using a dispersive liquid-liquid microextraction (DLLME) method. Four paraben derivatives including MP (normal: 0.68 ± 0.7; overweight: 1.40 ± 1.76; obese: 0.30 ± 0.26; p-value: 0.275), EP (normal: 0.14 ± 0.09; overweight: 0.72 ± 0.72; obese: 0.38 ± 0.05; p-value: 0.434), PP (normal: 0.05 ± 0.05; overweight: 0.06 ± 0.06; obese: 0.20 ± 0.17; p-value: 0.770), and BP (normal: 2.89 ± 1.80; overweight: 3.89 ± 6.48; obese: 5.80 ± 7.56; p-value: 0.341) were simultaneously detected in samples of maternal amniotic fluid using GC-MS. In 92.2% (n = 118) of pregnant women, the paraben derivatives (MP, EP, PP, BP) were detected. We found that considerable levels of MP, EP, PP, and BP existed in 22.6% (n = 29), 21.9% (n = 28), 29.7% (n = 38), and 85.2% (n = 109) of samples, respectively. In addition, the correlation between paraben concentrations in amniotic fluid and birth size was investigated. The results showed that an inverse significant association between MP and head circumference, chest, hip, and arm circumference. While a positive correlation between MP and height of newborn was observed. Similar correlations were observed for EP and weight, height, head circumference, chest, hip, and arm.

CONCLUSION

The current study indicated that parabens have been detected in amniotic fluid samples and a strong/possible correlation between exposure of pregnant women to parabens and the birth size of newborns.

Biotransformation and transplacental transfer of the anti-viral remdesivir and predominant metabolite, GS-441524 in pregnant rats

BACKGROUND

Remdesivir was the first prodrug approved to treat coronavirus disease 2019 (COVID-19) and has the potential to be used during pregnancy. However, it is not known whether remdesivir and its main metabolite, GS-441524 have the potential to cross the blood-placental barrier. We hypothesize that remdesivir and predominant metabolite GS-441524may cross the blood-placental barrier to reach the embryo tissues.

METHODS

To test this hypothesis, ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) coupled with multisite microdialysis was used to monitor the levels of remdesivir and the nucleoside analogue GS-441524 in the maternal blood, fetus, placenta, and amniotic fluid of pregnant Sprague-Dawley rats. The transplacental transfer was evaluated using the pharmacokinetic parameters of AUC and mother-to-fetus transfer ratio (AUCfetus/AUCmother).

FINDINGS

Our in-vivo results show that remdesivir is rapidly biotransformed into GS-441524 in the maternal blood, which then readily crossed the placenta with a mother-to-fetus transfer ratio of 0.51 ± 0.18. The Cmax and AUClast values of GS-441524 followed the order: maternal blood > amniotic fluid > fetus > placenta in rats.

INTERPRETATION

While remdesivir does not directly cross into the fetus, however, its main metabolite, GS-441524 readily crosses the placenta and can reside there for at least 4 hours as shown in the pregnant Sprague-Dawley rat model. These findings suggest that careful consideration should be taken for the use of remdesivir in the treatment of COVID-19 in pregnancy.

FUNDING

Ministry of Science and Technology of Taiwan.

Quantitation of linear and branched perfluoroalkane sulfonic acids (PFSAs) in women and infants during pregnancy and lactation

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are associated with negative health effects, and exposure during fetal life and infancy are of concern. A subgroup of PFAS, linear and branched perfluoroalkane sulfonic acids (PFSA), have significant differences in biochemical reactions, bioaccumulation and potential toxic exposure effects, and data on transfer of PFSA isomers from mother to baby through placenta or in breastmilk are scarce.

OBJECTIVES

The objective was to investigate differences in branched and linear PFSA isomers in never-pregnant, pregnant and postpartum women and infants.

METHODS

Serum concentrations of branched and linear, perfluorohexane sulfonate (PFHxS), perfluoroheptane sulfonate (PFHpS) and perfluorooctane sulfonate (PFOS) were measured in never-pregnant women (n = 158), pregnant and postpartum women (n = 114) and their infants (n = 94) at age six months.

RESULTS

There was a linear relation between maternal PFSA concentrations in pregnancy week 18 and the infant at age six months. The PFSA concentrations in maternal and infant serum varied with a factor up to 20. The maternal branched/ linear PFHxS ratio increased in the latter part of pregnancy (+45%) and remained high postpartum, and was substantially lower in the infants. Branched/linear PFHpS ratio increased during pregnancy and was highest in the infants, while the branched/linear PFOS ratio decreased in the mothers and was high in the infants.

DISCUSSION

The linear relations between PFSA concentrations in infants aged six months and mothers in pregnancy week 18 confirm that pregnancy and lactation are major excretion routes for PFSA, but accumulate in the infant. The observed great variability in PFSA burden among mothers and infants, as well as the reduced maternal transfer of branched PFHxS isoforms and increased transfer of branched PFOS isoforms compared to the respective linear isoforms to the infant, might impact adverse health effects associated with PFSA exposure, but this should be confirmed in future studies.

Exposure to legacy and novel perfluoroalkyl substance disturbs the metabolic homeostasis in pregnant women and fetuses: A metabolome-wide association study

BACKGROUND

Perfluoroalkyl substances (PFASs) exist extensively and several of these have been verified to be toxic. Prenatal exposure to PFASs has attracted much attention. Metabolome-wide association analyses can be used to explore the toxicity mechanisms of PFASs by identifying associated biomarkers.

OBJECTIVES

To evaluate associations between the metabolites in maternal and cord serum and internal exposure to several common PFASs.

METHODS

Paired maternal and cord serum samples were collected from 84 pregnant women who gave birth between 2015 and 2016. Seven legacy and two novel PFASs were measured. A nontarget metabolomic method and an iterative metabolite annotation based on metabolic pathways were applied to characterize the metabolic profiles. Linear regression adjusted with the false discovery rate and covariates was used to indicate the associations.

RESULTS

A total of 279 features in maternal serum and 338 features in cord serum were identified as metabolites associated with PFAS exposure. Perfluorooctanoic acid (PFOA) and perfluorohexane sulfonic acid (PFHxS) were two PFASs associated with more metabolites, while the two novel chlorinated polyfluorinated ether sulfonic acids (Cl-PFESAs) showed less relevance to the metabolome. With pathway enrichment analysis, we found that three fatty acid metabolisms and retinol metabolism were correlated with PFAS exposure in maternal blood, and that sterol metabolism showed the correlation in both maternal serum and cord serum.

CONCLUSIONS

We identified metabolites and pathways in pregnant women and fetuses associated with the exposure to several PFAS, indicating a promising application for metabolome-wide association studies. Additional research is needed to confirm causation.

Placental Passage of Humulone and Protopine in an Ex Vivo Human Perfusion System

The placental passage of humulone and protopine was investigated with a human ex vivo placental perfusion model. The model was first validated with diazepam and citalopram, 2 compounds known to cross the placental barrier, and antipyrine as a positive control. All compounds were quantified by partially validated U(H)PLC-MS/MS bioanalytical methods. Only a small portion of humulone initially present in the maternal circuit reached the fetal circuit. The humulone concentration in the maternal circuit rapidly decreased, likely due to metabolization in the placenta. Protopine was transferred from the maternal to the fetal circuit, with a steady-state reached after 90 min. None of the study compounds affected placental viability or functionality, as glucose consumption, lactate production, beta-human chorionic gonadotropin, and leptin release remained constant. Histopathological evaluation of all placental specimens showed unremarkable, age-appropriate parenchymal maturation with no pathologic findings.

Transplacental Behaviors of Organophosphate Tri- and Diesters Based on Paired Human Maternal and Cord Whole Blood: Efficiencies and Impact Factors

Organophosphate tri- and diesters (tri-OPEs and di-OPEs) were quantified in 63 paired maternal and cord whole blood samples collected in Hubei, China, in which tri-o-cresyl phosphate (ToCP) was predominant. The transplacental transfer efficiencies (expressed as cord blood to maternal blood (C:M) concentration ratios) of aryl-tri-OPEs, such as ToCP (1.61) and triphenyl phosphate (TPHP) (1.06), were higher than those of alkyl-tri-OPEs (0.66-0.76). For the target tri-OPEs and some traditional organic compounds, the C:M ratios first increased with log K_ow in the range of 1.63-5.23 and then decreased, showing a parabolic relationship. However, ToCP, with a log K_ow of 6.34, deviated from this relationship and displayed the highest C:M ratio (1.61). Molecular docking indicated a very strong binding affinity between ToCP and transthyretin, suggesting that ToCP might be actively transported by transthyretin in the placenta. The di-OPE levels in the blood samples were significantly lower than the corresponding tri-OPE levels, and those in the cord blood were influenced not only by their transplacental behaviors but also by their low excretion rates and the metabolic characteristics of their parent compounds in the fetus. This study provides useful information for accurately assessing the health risks posed by tri-OPEs to pregnant women and fetuses.

Telomere length in newborns is associated with exposure to low levels of air pollution during pregnancy

Telomere length (TL) is a biomarker of biological aging that may be affected by prenatal exposure to air pollution. The aim of this study was to assess the association between prenatal exposure to air pollution and TL in maternal blood cells (leukocytes), placenta and umbilical cord blood cells, sampled immediately after birth in 296 Danish mother-child pairs from a birth cohort. Exposure data was obtained using the high-resolution and spatial-temporal air pollution modeling system DEHM-UBM-AirGIS for PM_2.5, PM₁₀, SO₂, NH₄⁺, black carbon (BC), organic carbon (OC), CO, O₃, NO₂, and NO_x at residential and occupational addresses of the participating women for the full duration of the pregnancy. The association between prenatal exposure to air pollutants and TL was investigated using distributed lag models. There were significant and positive associations between TL in umbilical cord blood cells and prenatal exposure to BC, OC, NO₂, NO_x, CO, and O₃ during the second trimester. TL in umbilical cord blood was significantly and inversely associated with prenatal exposure to PM_2.5, BC, OC, SO₂, NH₄⁺, CO and NO₂ during the third trimester. There were similar inverse associations between TL from umbilical cord blood cells and air pollution exposure at the residential and occupational addresses. There were weaker or no associations between air pollution exposure and TL in placenta tissue and maternal blood cells. In conclusion, both the second and third trimesters of pregnancy are shown to be sensitive windows of exposure to air pollution affecting fetal TL.

The impact of intrauterine growth restriction on cytochrome P450 enzyme expression and activity

With the increased prevalence of non-communicable disease and availability of medications to treat these and other conditions, a pregnancy free from prescribed medication exposure is rare. Up to 99% of women take at least one medication during pregnancy. These medications can be divided into those used to improve maternal health and wellbeing (e.g., analgesics, antidepressants, antidiabetics, antiasthmatics), and those used to promote the baby's wellbeing in either fetal (e.g., anti-arrhythmics) or postnatal life (e.g., antenatal glucocorticoids). These medications are needed for pre-existing or coincidental illnesses in the mother, maternal conditions induced by the pregnancy itself through to conditions that arise in the fetus or that will be encountered by the newborn. Thus, medications administered to the mother may be used to treat the mother, the fetus or both. Metabolism of medications is regulated by a range of physiological processes that change during pregnancy. Other pathological processes such as placental insufficiency can in turn have both immediate and lifelong adverse health consequences for babies. Individuals born growth restricted are more likely to require medications but may also have an altered ability to metabolise these medications in fetal and postnatal life. This review aims to determine the effect of suboptimal fetal growth on the fetal expression of the drug metabolising enzymes (DMEs) that convert medications into active or inactive metabolites, and the transporters that remove both these medications and their metabolites from the fetal compartment.

Adaptive optimal target controlled infusion algorithm to prevent hypotension associated with labor epidural: An adaptive dynamic programming approach

Patients receiving labor epidurals commonly experience arterial hypotension as a complication of neuraxial block. The purpose of this study was to design an adaptive optimal controller for an infusion system to regulate mean arterial pressure. A state-space model relating mean arterial pressure to Norepinephrine (NE) infusion rate was derived for controller design. A data-driven adaptive optimal control algorithm was developed based on adaptive dynamic programming (ADP). The stability and disturbance rejection ability of the closed-loop system were tested via a simulation model calibrated using available clinical data. Simulation results indicated that the settling time was six minutes and the system showed effective disturbance rejection. The results also demonstrate that the adaptive optimal control algorithm would achieve individualized control of mean arterial pressure in pregnant patients with no prior knowledge of patient parameters.

Transplacental Transfer of Per- and Polyfluoroalkyl Substances Identified in Paired Maternal and Cord Sera Using Suspect and Nontarget Screening

Novel per- and polyfluoroalkyl substances (PFASs) in various environmental media have attracted increasing attention; however, the information regarding PFASs exposure in pregnant women and fetuses is insufficient. In this study, we built and applied suspect and nontarget screening strategies based on the mass difference of the CF₂, CF₂O, and CH₂CF₂ units to select potential novel PFASs from 117 paired maternal and cord sera. In total, 10 legacy PFASs and 19 novel PFASs from 10 classes were identified to be above confidence levels 3, among which 14 were not previously reported in human serum. Novel PFASs accounted for a considerable percentage of total PFASs in pregnant women and can be transferred to fetuses at non-negligible concentrations (i.e., 27.9% and 30.3% of total PFAS intensities in maternal and cord sera, respectively). The transplacental transfer efficiency (TTE) of PFASs showed a U-shape trend in the series of perfluoroalkyl carboxylic acids, perfluoroalkyl sulfonic acids, and unsaturated perfluorinated alcohols. The TTE of novel PFASs is suggested to be structure-dependent, based on a flexible docking experiment. This study provides comprehensive TTE information on legacy and novel PFASs for the first time, and additional toxicity studies are needed to evaluate the risk of novel PFASs further.

Profiles of parabens and their metabolites in paired maternal-fetal serum, urine and amniotic fluid and their implications for placental transfer

Six parabens and their four metabolites were measured in paired maternal serum (MS) and cord serum (CS) samples collected from 95 pregnant women to elucidate placental transfer of this class of compounds. Matched maternal urine (MU) and amniotic fluid (AF) collected from 13 of 95 pregnant women were also analyzed to examine partition of these chemicals between maternal and fetal tissues. The placental transfer rates (PTRs; concentration ratio of parabens between CS and MS) of methyl- (MeP), ethyl- (EtP), propyl-parabens (PrP) were 0.81, 0.63, and 0.60, respectively. Furthermore, the PTRs of OH-MeP (0.93) and OH-EtP (1.8) were higher than those of their corresponding parent parabens, which suggested that hydroxylation increased placental transfer rates of parabens. Structure-dependent placental transfer mechanisms were observed. A significant negative correlation between molecular weights (or log K_ow) of MeP, EtP, PrP, and p-hydroxy benzoic acid (4-HB) and PTRs suggested passive diffusion as a mechanism of placental transfer of these chemicals. Nevertheless, other hydroxylated metabolites (OH-EtP, OH-MeP, and 3,4-dihydroxy benzoic acid (3,4-DHB)) showed a positive correlation between molecular weight (or log K_ow) and PTRs, which suggested that the placental transfer is mediated by protein binding of these metabolites. The MU to MS concentration ratios of MeP (MU/MS_MeP) and PrP (MU/MS_PrP) were 71 and 81, respectively, and MU/MS_MeP was two orders of magnitude higher than that found for the metabolite (MU/MS_OH-MeP: 0.35), suggesting that hydroxylation metabolite reduced urinary elimination of parabens. To our knowledge, this is the first time to report the occurrence and distribution of parabens and their metabolites in paired maternal-fetal serum, urine, and AF samples in China. Our results provide novel information on placental transfer of parabens and their metabolites.

Biological barriers, and the influence of protein binding on the passage of drugs across them

Drug-protein binding plays a key role in determining the pharmacokinetics of a drug. The distribution and protein binding ability of a drug changes over a lifetime, and are important considerations during pregnancy and lactation. Although proteins are a significant fraction in plasma composition, they also exist beyond the bloodstream and bind with drugs in the skin, tissues or organs. Protein binding influences the bioavailability and distribution of active compounds, and is a limiting factor in the passage of drugs across biological membranes and barriers: drugs are often unable to cross membranes mainly due to the high molecular mass of the drug-protein complex, thus resulting in the accumulation of the active compounds and a significant reduction of their pharmacological activity. This review describes the consequences of drug-protein binding on drug transport across physiological barriers, whose role is to allow the passage of essential substances-such as nutrients or oxygen, but not of xenobiotics. The placental barrier regulates passage of xenobiotics into a fetus and protects the unborn organism. The blood-brain barrier is the most important barrier in the entire organism and the skin separates the human body from the environment.

Concentrations of bisphenol A and its alternatives in paired maternal-fetal urine, serum and amniotic fluid from an e-waste dismantling area in China

Bisphenol A (BPA) and its alternatives are suspected endocrine disruptors. However, prenatal exposure and transplacental transfer of bisphenols (BPs is still limited. Therefore, BPA and its six alternatives in maternal serum (MS), maternal urine (MU), cord serum (CS), and amniotic fluid (AF) samples collected from 106 maternal-fetal pairs in an e-waste dismantling site in Southern China were determined. Bisphenol AF (BPAF) and bisphenol S (BPS) were the dominant BPA alternatives observed in MS and CS, and the geometric mean (GM) concentration of BPAF (0.013 ng/mL in MS, 0.097 ng/mL in CS) and BPS (0.01 ng/mL in MS, 0.03 ng/mL in CS) in MS and CS was lower than that of BPA (0.5 ng/mL in MS, 1.2 ng/mL in CS). The ratios of BPA concentrations between MU and MS (MU:MS ratio) were over three times higher than those of AF and CS (AF:CS ratio), thereby suggesting low biotransformation/metabolism of BPA in fetuses. The placental transfer rates of BPs (i.e., CS:MS ratio) were compound-specific (BPAF 3.26, BPA 1.94, BPS 1.11). Results suggest that BPA and its alternatives can pass through the placental barrier. The placental transfer rates of BPs are positively related to molecular weight or log K_ow values. This finding indicates that an active transport is responsible for the placental transfer of BPs.

Transplacental transfer mechanism of organochlorine pesticides: An in vitro transcellular transport study

Recent studies show that, even after being banned for agricultural applications for over 30 years, organochlorine pesticides (OCPs), including hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethane (DDT) and its metabolites (DDXs), can still be found in various biological matrices and pose a potential hazard to the fetus in the womb. This study aimed to investigate the possible transplacental transfer mechanism of OCPs using an in vitro placental model. The results showed that for HCHs and DDXs, the placenta had a potential protection mechanism for the fetus by having higher efflux than intake active transport efficiency to transfer the xenobiotic out of the fetal circulation. No enantiomer-specific transport was observed for the chiral OCPs in vitro, hints simple diffusion played the major role in the transplacental transfer. Metabolic and transporter inhibitors were applied in the transepithelial transport experiment to evaluate the role that major transporting protein played in the active efflux process. The ATP production inhibitors were observed to have significant inhibition on transfer, proving the hypothesis that active transport participates in the transplacental transport of OCPs in humans. Multiple transporters contributed simultaneously in the active transport for the OCPs. In this study, we could confirm that the transplacental transfer of OCPs is a combination of simple diffusion and active transport. ATP-binding cassette (ABC) superfamily transporters on the placenta contribute in the active transport. These findings could improve the understanding of the mechanisms of transplacental transfer of the OCPs.

Brief report: Metabolic acidosis in newborn infants following maternal use of acetazolamide during pregnancy

 The information regarding fetal effects of acetazolamide use during pregnancy and lactation is sparse. We report the clinical and pharmacodynamic characteristics of maternal acetazolamide use and the timing of its effects on acid-base balance in three cases who presented with metabolic acidosis in the newborn period. We found that the infants' clinical status soon after birth was inconsistently correlated with maternal drug dose and concentrations of medication in maternal serum. However, there was low transfer of the drug in breast milk and its use did not affect clinical symptomatology. We also present a review of literature on this subject to help consolidate our current knowledge on this topic.

Prevalence, Biotransformation, and Maternal Transfer of Synthetic Phenolic Antioxidants in Pregnant Women from South China

Synthetic phenolic antioxidants (SPAs) have been identified as an emerging group of contaminants in recent years. However, there are significant gaps in our knowledge of human prenatal exposure to these synthetic chemicals. In this study, a set of eight SPAs and four major transformation products (TPs) were systematically analyzed in matched samples of maternal plasma, cord plasma, and placenta from a population of pregnant women. Five of the eight target SPAs and all four target TPs were frequently detected in the maternal-placental-fetal unit, indicating prenatal exposure to SPAs and the transfer of SPAs across the placenta. In the three matrices, 2,6-di-tert-butyl-hydroxytoluene (BHT), 2,4-di-tert-butylphenol (DBP), and 2,2'-methylenebis(4-methyl-6-tert-butylphenol) (AO 2246) were identified as the most abundant SPAs, while 2,6-di-tert-butyl-1,4-benzoquinone (BHT-Q) and 2,6-di-tert-butyl-4-hydroxy-4-methyl-2,5-cyclohexadienone (BHT-quinol) were identified as the predominant TPs of BHT. In the maternal plasma, concentrations of both BHT-Q and BHT-quinol were significantly correlated with BHT (p < 0.001), suggesting that the two TPs mainly originated from the biotransformation of BHT itself in pregnant women. The transplacental transfer efficiencies (TTEs) of the SPAs and TPs were structure-dependent and generally less than 1. Significantly higher TTEs for four target TPs than their parent BHT were identified. To our knowledge, this study provides the first evidence that SPAs and TPs transfer across the placenta in pregnant women.

The brain-placental axis: Therapeutic and pharmacological relevancy to pregnancy

The placenta plays a critical role in mammalian reproduction. Although it is a transient organ, its function is indispensable to communication between the mother and fetus, and supply of nutrients and oxygen to the growing fetus. During pregnancy, the placenta is vulnerable to various intrinsic and extrinsic conditions which can result in increased risk of fetal neurodevelopmental disorders as well as fetal death. The placenta controls the neuroendocrine secretion in the brain as a means of adaptive processes to safeguard the fetus from adverse programs, to optimize fetal development and other physiological changes necessary for reproductive success. Although a wealth of information is available on neuroendocrine functions in pregnancy, they are largely limited to the regulation of hypothalamus-pituitary-adrenal/gonad (HPA/ HPG) axis, particularly the oxytocin and prolactin system. There is a major gap in knowledge on systems-level functional interaction between the brain and placenta. In this review, we aim to outline the current state of knowledge about the brain-placental axis with description of the functional interactions between the placenta and the maternal and fetal brain. While describing the brain-placental interactions, a special emphasis has been given on the therapeutics and pharmacology of the placental receptors to neuroligands expressed in the brain during gestation. As a key feature of this review, we outline the prospects of integrated pharmacogenomics, single-cell sequencing and organ-on-chip systems to foster priority areas in this field of research. Finally, we remark on the application of precision genomics approaches to study the brain-placental axis in order to accelerate personalized medicine and therapeutics to treat placental and fetal brain disorders.

Surface-Functionalized Nanoparticles as Efficient Tools in Targeted Therapy of Pregnancy Complications

Minimizing exposure of the fetus to medication and reducing adverse off-target effects in the mother are the primary challenges in developing novel drugs to treat pregnancy complications. Nanomedicine has introduced opportunities for the development of novel platforms enabling targeted delivery of drugs in pregnancy. This review sets out to discuss the advances and potential of surface-functionalized nanoparticles in the targeted therapy of pregnancy complications. We first describe the human placental anatomy, which is fundamental for developing placenta-targeted therapy, and then we review current knowledge of nanoparticle transplacental transport mechanisms. Meanwhile, recent surface-functionalized nanoparticles for targeting the uterus and placenta are examined. Indeed, surface-functionalized nanoparticles could help prevent transplacental passage and promote placental-specific drug delivery, thereby enhancing efficacy and improving safety. We have achieved promising results in targeting the placenta via placental chondroitin sulfate A (plCSA), which is exclusively expressed in the placenta, using plCSA binding peptide (plCSA-BP)-decorated nanoparticles. Others have also focused on using placenta- and uterus-enriched molecules as targets to deliver therapeutics via surface-functionalized nanoparticles. Additionally, we propose that placenta-specific exosomes and surface-modified exosomes might be potential tools in the targeted therapy of pregnancy complications. Altogether, surface-functionalized nanoparticles have great potential value as clinical tools in the targeted therapy of pregnancy complications.

Trastuzumab in the Treatment of Pregnant Breast Cancer Patients - an Overview of the Literature

Breast cancer is one of the most common malignancies which appear during pregnancy. Since women are increasingly not giving birth until they are at a more advanced age, it can be assumed that the incidence of pregnancy-related breast cancers will continue to increase in the future. Because of pregnancy-induced changes and conservative diagnosis, these carcinomas are frequently not detected until they are at an advanced stage and thus generally require systemic adjuvant therapy. The available data on optimal chemotherapeutic management are limited. Particularly for the use of the target agent trastuzumab which could crucially contribute to improving the prognosis in the therapy of HER2-overexpressing breast cancer in non-pregnant women, there is a lack of definitive information regarding the profile of action and safety in pregnancy as well as with regard to any long-term effects on the child. Thirty-eight pregnancies on trastuzumab for the treatment of breast cancer were able to be analysed in the literature currently available. Information can be gained from this and conclusions can be drawn which can individualise and decisively improve therapeutic options in the future for the pregnant breast cancer patient.

Twin study confirms virtually identical prenatal alcohol exposures can lead to markedly different fetal alcohol spectrum disorder outcomes-fetal genetics influences fetal vulnerability

BACKGROUND

Risk of fetal alcohol spectrum disorder (FASD) is not based solely on the timing and level of prenatal alcohol exposure (PAE). The effects of teratogens can be modified by genetic differences in fetal susceptibility and resistance. This is best illustrated in twins.

OBJECTIVE

To compare the prevalence and magnitude of pairwise discordance in FASD diagnoses across monozygotic twins, dizygotic twins, full-siblings, and half-siblings sharing a common birth mother.

METHODS

Data from the Fetal Alcohol Syndrome Diagnostic & Prevention Network clinical database was used. Sibling pairs were matched on age and PAE, raised together, and diagnosed by the same University of Washington interdisciplinary team using the FASD 4-Digit Code. This design sought to assess and isolate the role of genetics on fetal vulnerability/resistance to the teratogenic effects of PAE by eliminating or minimizing pairwise discordance in PAE and other prenatal/postnatal risk factors.

RESULTS

As genetic relatedness between siblings decreased from 100% to 50% to 50% to 25% across the four groups (9 monozygotic, 39 dizygotic, 27 full-sibling and 9 half-sibling pairs, respectively), the prevalence of pairwise discordance in FASD diagnoses increased from 0% to 44% to 59% to 78%. Despite virtually identical PAE, 4 pairs of dizygotic twins had FASD diagnoses at opposite ends of the fetal alcohol spectrum-Partial Fetal Alcohol Syndrome versus Neurobehavioral Disorder/Alcohol-Exposed.

CONCLUSION

Despite virtually identical PAE, fetuses can experience vastly different FASD outcomes. Thus, to protect all fetuses, especially the most genetically vulnerable, the only safe amount to drink is none at all.

Placenta-specific drug delivery by trophoblast-targeted nanoparticles in mice

Rationale: The availability of therapeutics to treat pregnancy complications is severely lacking, mainly due to the risk of harm to the fetus. In placental malaria, Plasmodium falciparum-infected erythrocytes (IEs) accumulate in the placenta by adhering to chondroitin sulfate A (CSA) on the surfaces of trophoblasts. Based on this principle, we have developed a method for targeted delivery of payloads to the placenta using a synthetic placental CSA-binding peptide (plCSA-BP) derived from VAR2CSA, a CSA-binding protein expressed on IEs.

Methods: A biotinylated plCSA-BP was used to examine the specificity of plCSA-BP binding to mouse and human placental tissue in tissue sections in vitro. Different nanoparticles, including plCSA-BP-conjugated nanoparticles loaded with indocyanine green (plCSA-INPs) or methotrexate (plCSA-MNPs), were administered intravenously to pregnant mice to test their efficiency at drug delivery to the placenta in vivo. The tissue distribution and localization of the plCSA-INPs were monitored in live animals using an IVIS imaging system. The effect of plCSA-MNPs on fetal and placental development and pregnancy outcome were examined using a small-animal high-frequency ultrasound (HFUS) imaging system, and the concentrations of methotrexate in fetal and placental tissues were measured using high-performance liquid chromatography (HPLC).

Results: plCSA-BP binds specifically to trophoblasts and not to other cell types in the placenta or to CSA-expressing cells in other tissues. Moreover, we found that intravenously administered plCSA-INPs accumulate in the mouse placenta, and ex vivo analysis of the fetuses and placentas confirmed placenta-specific delivery of these nanoparticles. We also demonstrate successful delivery of methotrexate specifically to placental cells by plCSA-BP-conjugated nanoparticles, resulting in dramatic impairment of placental and fetal development. Importantly, plCSA-MNPs treatment had no apparent adverse effects on maternal tissues.

Conclusion: These results demonstrate that plCSA-BP-guided nanoparticles could be used for the targeted delivery of payloads to the placenta and serve as a novel placenta-specific drug delivery option.

Investigations on clonazepam-loaded polymeric micelle-like nanoparticles for safe drug administration during pregnancy

Medication during pregnancy is often a necessity for women to treat their acute or chronic diseases. The goal of this study is to evaluate the potential of micelle-like nanoparticles (MNP) for providing safe drug usage in pregnancy and protect both foetus and mother from medication side effects. Clonazepam-loaded MNP were prepared from copolymers [polystyrene-poly(acrylic acid) (PS-PAA), poly(ethylene glycol)-b-poly(lactic acid) (PEG-PLA) and distearyl-sn-glycero-3-phosphoethanolamine-N-[methoxy-poly(ethylene glycol) (PEG-DSPE)] with varying monomer ratios and their drug-loading efficiency, drug release ratio, particle size, surface charge and morphology were characterised. The cellular transport and cytotoxicity experiments were conducted on clonazepam and MNP formulations using placenta-choriocarcinoma-BeWo and brain-endothelial-bEnd3 cells. Clonazepam-loaded PEG₅₀₀₀-PLA₄₅₀₀ MNP reduced the drug transport through BeWo cells demonstrating that MNP may lower foetal drug exposure, thus reduce the drug side effects. However, lipofectamine modified MNP improved the transport of clonazepam and found to be promising for brain and in-utero-specific drug treatment.

Chlorinated Polyfluoroalkyl Ether Sulfonic Acids in Matched Maternal, Cord, and Placenta Samples: A Study of Transplacental Transfer

Currently, information regarding concentrations of chlorinated polyfluoroalkyl ether sulfonic acids (Cl-PFESAs) in human placenta does not exist. The main objective of this study was to assess the occurrence and distribution of two Cl-PFESAs, 6:2 Cl-PFESA and 8:2 Cl-PFESA, in maternal serum, umbilical cord serum, and placenta to better assess the transport pathways related to human prenatal exposure. The widely studied perfluorooctanesulfonate (PFOS) was studied for comparison. This study was a hospital-based survey involving quantitative determination of Cl-PFESA and PFOS concentrations in maternal serum (n = 32), cord serum (n = 32), and placenta (n = 32) samples from women in Wuhan, China. The results indicate that Cl-PFESAs can efficiently be transported across placenta, with median exposure levels of 0.60 and 0.01 ng/mL for 6:2 Cl-PFESA and 8:2 Cl-PFESA in the cord sera, respectively. Concentrations of the target compounds in maternal sera, cord sera, and placentas decreased in the following order: PFOS > 6:2 Cl-PFESA > 8:2 Cl-PFESA. Similar patterns were observed in maternal sera, cord sera, and placentas for Cl-PFESAs, with concentrations decreasing in the following order: maternal sera > cord sera > placentas. Significant correlations were observed among 6:2 Cl-PFESA, 8:2 Cl-PFESA, and PFOS concentrations in the maternal serum, cord serum, and placenta samples (r > 0.7; p < 0.001). The median value of R_CM (ratio of cord serum to maternal serum concentration) of 6:2 Cl-PFESA was 0.403, indicating a relatively high (∼40%) placental transfer efficiency. 8:2 Cl-PFESA was transported across placenta to a greater extent than 6:2 Cl-PFESA was, likely because of its higher hydrophobicity and lower plasma protein binding affinity. To the best of our knowledge, this is the first study to report the occurrence and distribution of 6:2 Cl-PFESA and 8:2 Cl-PFESA in human placenta. The findings improve our understanding of the mechanisms of transplacental transfer and neonatal exposure to these important PFOS alternatives.

Organophosphorus Flame Retardants in Pregnant Women and Their Transfer to Chorionic Villi

The potential for prenatal exposure has recently raised concerns over the health risks of endocrine disruptors; however, knowledge about human prenatal exposure to organophosphorus flame retardants (OPFRs) is lacking. In this study, 2-ethylhexyl diphenyl phosphate (EHDPP), tributyl phosphate (TBP), triphenyl phosphate (TPHP), and tris(2-chloroethyl) phosphate (TCEP) were detected in the majority of chorionic villus samples, with median concentrations of 13.6, 18.8, 11.1, and 0.51 ng/g of dry weight (dw), respectively, significantly higher than those in the matching maternal decidua samples (5.96, 10.8, 1.44, and 0.26 ng/g of dw, respectively). The ratios of concentrations in chorionic villi (containing embryos) to those in maternal deciduae (CMRs) were 4.17, 3.82, 2.81, and 2.00 for EHDPP, TPHP, TBP, and TCEP, respectively, which correlated with their log K_ow values (p = 0.003). The results of transthyretin (TTR) binding assays indicated that the stronger the binding ability to TTR, the higher the CMRs. The median concentrations of the metabolites diphenyl phosphate (DPHP), dibutyl phosphate (DBP), and bis(2-chloroethyl) phosphate (BCEP) were 4.11, 429, and 157 ng/g of dw in chorionic villi, higher than those in deciduae (1.64, 181, and 25.4 ng/g of dw, respectively). The ratios of DPHP/TPHP and DPHP/EHDPP were 0.20 and 0.43 in chorionic villi and 1.24 and 2.03 in deciduae, respectively, much lower than those of DBP/TBP and BCEP/TCEP (20.9 and 165.6 in chorionic villi and 13.1 and 35.3 in deciduae, respectively), suggesting that the difference in metabolism between the deciduae and chorionic villi would affect their maternal transfer.

Isomer-Specific Transplacental Transfer of Perfluoroalkyl Acids: Results from a Survey of Paired Maternal, Cord Sera, and Placentas

Currently, information regarding isomer-specific concentrations of PFHxS, PFOS, and PFOA in human placenta, and corresponding placental-maternal ratios (R_PM) 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 (R_CM) were ordered n < iso < 4m < (3 + 5)m < 1m < ∑m₂. The R_PM 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 R_CM and R_PM. 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, R_PM 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.

Uterus-targeted liposomes for preterm labor management: studies in pregnant mice

Preterm labor caused by uterine contractions is a major contributor to neonatal morbidity and mortality. Treatment intended to reduce uterine contractions include tocolytic agents, such as indomethacin. Unfortunately, clinically used tocolytics are frequently inefficient and cross the placenta causing fetal side effects. Here we show for the first time in obstetrics the use of a targeted nanoparticle directed to the pregnant uterus and loaded with a tocolytic for reducing its placental passage and sustaining its efficacy. Nanoliposomes encapsulating indomethacin and decorated with clinically used oxytocin receptor antagonist were designed and evaluated in-vitro, ex-vivo and in-vivo. The proposed approach resulted in targeting uterine cells in-vitro, inhibiting uterine contractions ex-vivo, while doubling uterine drug concentration, decreasing fetal levels, and maintaining the preterm birth rate in vivo in a pregnant mouse model. This promising approach opens new horizons for drug development in obstetrics that could greatly impact preterm birth, which currently has no successful treatments.

The Prenatal Environment in Twin Studies: A Review on Chorionicity

A literature search was conducted to identify articles examining the association of chorionicity (e.g., whether twins share a single chorion and thus placenta or have separate chorions/placentas) and genetics, psychiatry/behavior, and neurological manifestations in humans twins and higher-order multiples. The main aim was to assess how frequently chorionicity has been examined in relation to heritability estimates, and to assess which phenotypes may be most sensitive to, or affected by, bias in heritability estimates because of chorionicity. Consistent with the theory that some chorionicity effects could lead to overestimation and others to underestimation of heritability, there were instances of each across the many phenotypes reviewed. However, firm conclusions should not be drawn since some of the outcomes were only examined in one or few studies and often sample sizes were small. While the evidence for bias due to chorionicity was mixed or null for many outcomes, results do, however, consistently suggest that heritability estimates are underestimated for measures of birth weight and early growth when chorionicity is not taken into account.

Association between delta-aminolevulinic acid dehydratase polymorphism and placental lead levels

Lead inhibits the delta-aminolevulinic acid dehydratase (ALAD) activity and results in neurotoxic aminolevulinic acid accumulation in the blood. During pregnancy, lead in the maternal blood can easily cross the placenta. The aim of this study was to determine whether the maternal ALAD G177C polymorphism (rs1800435) was related to the placental lead levels. The study population comprised 97 blood samples taken from mothers to investigate ALAD G177C polymorphism and their placentas to measure lead levels. ALAD G177C polymorphism was detected by standard polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) technique and atomic absorption spectrometry (AAS) equipped with a graphite furnace and Zeeman background correction system was used for lead determination. The median placental lead levels for ALAD1-1, ALAD1-2 and ALAD2-2 genotypes were 7.54 μg/kg, 11.78 μg/kg and 18.53 μg/kg, respectively. Statistically significant association was found between the maternal ALAD G177C polymorphism and placental lead levels (p<0.05). This study suggested that maternal ALAD G177C polymorphism was associated with placental lead levels.

Maternal use of antidepressant or anxiolytic medication during pregnancy and childhood neurodevelopmental outcomes: a systematic review

Antidepressant and anxiolytic medications are widely prescribed and used by pregnant women for acute and maintenance therapy. These drugs are able to pass the placental barrier, and may potentially influence fetal and brain development. It is possible that exposure to prenatal antidepressants or anxiolytic medication may disturb neurotransmitter systems in the brain and have long-lasting consequences on neurodevelopment in the offspring. As all medication during pregnancy may pose a certain risk to the developing fetus, the potential benefits of the medication must be weighed against the risks for both mother and her unborn child. Therefore, information to guide patients and physicians to make a well-balanced decision for the appropriate treatment during pregnancy is needed. In this systematic review, an overview of maternal use of antidepressant or anxiolytic medication during pregnancy and childhood neurodevelopmental outcomes is provided. Some studies indicate a relation between prenatal exposure to antidepressants and adverse neurodevelopmental outcomes such as delayed motor development/motor control, social difficulties, internalizing problems and autism, but cannot rule out confounding by indication. Overall, the results of the observational studies have been inconsistent, which makes translation of the findings into clinical recommendations difficult. More well-designed observational studies and also randomized controlled trials (e.g., maintenance treatment vs. cessation) are needed to move forward and provide a comprehensive evaluation of the risks and benefits of antidepressant and anxiolytic use during pregnancy.

Evaluation of the maternal-fetal transfer of granisetron in an ex vivo placenta perfusion model

The objective of this study was to estimate maternal-fetal transplacental passage of granisetron in an ex vivo placental perfusion model. Term human placentas (N=8) were collected immediately after delivery. A single cotyledon from each placenta was perfused granisetron concentration to mimic systemic maternal peak plasma concentrations following either IV (50ng/mL) or transdermal administration (5ng/mL). To assess drug transfer and accumulation, samples were collected from maternal and fetal compartments. In the 50ng/mL open model, the mean transport fraction was 0.21±0.08 with clearance index of 0.53±0.66. Fetal peak concentrations achieved was 5.6±6.6ng/mL with mean accumulation of 5.35±6.4ng/mL. No drug was detected in the fetal compartment with the 5ng/mL models. Transplacental passage of granisetron was inconsistent at the 50ng/mL concentration that achieved with IV dosing. However, there consistently was no detectable passage in all the placentas evaluated of the granisetron at 5ng/mL concentration that would be achieved after transdermal patch administration.

Utilization of an ex vivo human placental perfusion model to predict potential fetal exposure to carboplatin during pregnancy

OBJECTIVE

The objective of this study was to determine the fetal drug compartment concentrations when various concentrations of carboplatin cross the placental-trophoblastic barrier and the effect on the fetal kidneys.

STUDY DESIGN

An ex vivo human placenta perfusion model was utilized. Term human placentae (n = 9) were collected immediately after delivery and then reperfused with plasma concentrations achieved with carboplatin an area under the curve of 5 (1000 ng/mL), 7.5 (5000 ng/mL), or 11 (11,000 ng/mL). Antipyrine was used as a reference compound. Samples were collected over 2 hours. Placental transfer was evaluated by computation of transport fraction and clearance index. Primary cells isolated by explant culture of 16-18 week old fetal organ tissues were incubated with carboplatin for up to 48 hours with untreated cell as controls. Immunohistochemical, flow cytometry analysis, and immunoblotting were applied for the expression of apoptosis-related proteins.

RESULTS

Mean transport fractions for carboplatin at low, middle, and high concentrations were 0.05 ± 0.02, 0.04 ± 0.01, and 0.10 ± 0.01, respectively, with clearance indexes of 0.22 ± 0.01, 0.14 ± 0.08, and 0.50 ± 0.07, respectively. The fetal peak concentrations of carboplatin achieved were 61 ± 39 ng/mL (low), 375 ± 248 ng/mL (middle), and 2081 ± 529 ng/mL (high). Fetal kidney cells exposed to carboplatin showed a concentration-dependent increased expression of apoptosis-inducing factor and p53 apoptosis proteins and a time-dependent increase in expression Bax apoptosis protein expression. Apoptosis was confirmed at the high concentration by flow cytometry.

CONCLUSION

Doses of carboplatin up to an area under the curve of 7.5 were not associated with significant placental transfer, fetal exposure, or fetal toxic effects. This suggests it might not be necessary to empirically reduce carboplatin doses in pregnant women.

Effects of addictive substances during pregnancy and infancy and their analysis in biological materials

The use of addictive substances during pregnancy is a serious social problem, not only because of effects on the health of the woman and child, but also because drug or alcohol dependency detracts from child care and enhances the prospect of child neglect and family breakdown. Developing additive substance abuse treatment programs for pregnant women is socially important and can help ensure the health of babies, prevent subsequent developmental and behavioral problems (i.e., from intake of alcohol or other additive substances such as methamphetamine, cocaine,or heroine) and can reduce addiction costs to society. Because women of childbearing age often abuse controlled substances during their pregnancy, it is important to undertake biomonitoring of these substances in biological samples taken from the pregnant or nursing mother (e.g., blood, urine,hair, breast milk, sweat, oral fluids, etc.), from the fetus and newborn (e.g., meconium,cord blood, neonatal hair and urine) and from both the mother and fetus (i.e.,amniotic fluids and placenta). The choice of specimens to be analyzed is determined by many factors; however, the most important is knowledge of the chemical and physical characteristics of a substance and the route of it administration. Maternal and neonatal biological materials reflect exposures that occur over a specific time period, and each of these biological specimens has different advantages and disadvantages,in terms of accuracy, time window of exposure and cost/benefit ratio.Sampling the placenta may be the most important biomonitoring choice for assessing in utero exposure to addictive substances. The use of the placenta in scientific research causes a minimum of ethical problems, partly because its sampling is noninvasive, causes no harm to mother or child, and partly because, in any case,placentas are discarded and incinerated after birth. Such samples, when properly analyzed, may provide key essential information about fetal exposure to toxic substances, and may provide the groundwork for protecting the fetus or newborn and the mother from further damage.Several sensitive and specific bioanalytical methods are commonly utilized to accurately measure for drug biomarkers of in utero drug exposure. Moreover, several immunoassay methods are used to rapidly screen for drugs in many biological specimen types. However, results from immunoassays should be carefully interpreted,and should be confirmed by more specific and sensitive chromatographic methods, such as GC-MS or LC-MS. Although techniques for analysis of addictive substances are still being developed or are being refined, current methods are efficient and sensitive and provide valuable information on human exposures to addictive substances and their metabolites.

Prenatal exposure to substance of abuse: a worldwide problem

Substance abuse during pregnancy is an important public health issue affecting the mother and the growing infant. Preterm labor, miscarriage, abruption and postpartum hemorrhage are obstetric complications which have been associated with women who are dependent on abused substances. Moreover, women are also at an increased risk of medical problems such as poor nutrition, anemia, urinary tract infections as well as sexually transmitted infections, hepatitis, HIV and problems related to infection. Intrauterine growth restriction, prematurity, stillbirth, neonatal abstinence syndrome, and Sudden Infant Death Syndrome represent only some of fetal effects. Later on, during childhood, it has been shown that in utero exposure to substances of abuse is associated with increased rates of respiratory infections, asthma, ear and sinus infections. Moreover, these children are more irritable, have difficulty focusing their attention, and have more behavioral problems. Therefore, the assessment of in utero exposure to abused substance is extremely necessary and is relevant for the care of the mother and the offspring. In this sense, several approaches are possible; however, recently the evaluation of in utero exposure to abused drugs has been achieved by testing biological specimens coming from fetus or newborn, pregnant or nursing mother, or from both the fetus and the mother. Maternal and neonatal biological materials reflect exposure in a specific time period and each of them has different advantages and disadvantages in terms of accuracy, time window of exposure and cost/benefit ratio. The methodology for identification and determination of abused substances in biological materials are of great importance. Consequently, sensitive and specific bioanalytical methods are necessary to accurately measure biomarkers. Different immunoassays methods are used as screening methods for drug testing in the above reported specimens, however, the results from immunoassays should be carefully interpreted and confirmed by a more specific and sensitive chromatographic methods such as GC-MS or LC-MS. The interest in the development and optimization of analytical techniques to detect abused substances in different specimens is explained by the several possibilities and information that they can provide.

Food allergens are transferred intact across the rat blood-placental barrier in vivo

We investigated the mechanism of transplacental macromolecular transport in rats on the nineteenth day of pregnancy using tracers, transmission electron microscopy and immunohistochemistry. The blood-placental barrier of full-term rat placentas was composed of a trilaminar layer of trophoblast cells that separates the fetal capillaries from the maternal blood spaces: a layer of cytotrophoblasts lining the maternal blood space and a bilayer of syncytiotrophoblast surrounding the fetal capillaries. Horseradish peroxidase, intravenously injected into the maternal circulation, was found in the maternal blood spaces, the interspaces between the cytotrophoblasts and the syncytiotrophoblast I, many pits and small vesicles in the syncytiotrophoblast I, vesicles of the syncytiotrophoblast II, fetal connective tissue and fetal capillaries. Intravenously injected ovalbumin was detected in the maternal blood spaces, a trilaminar layer and the fetal capillaries. Neonatal Fc receptor (FcRn), a receptor for IgG, was localized at the maternal side of the blood-placental barrier. These results show that the structure of the rat blood-placental barrier is quite similar to the human blood-placental barrier, and non-specific macromolecules and food allergens may penetrate through the blood-placental barrier of the full-term placenta from the maternal to fetal circulation mediated by FcRn.

[Caesarean sections under regional anesthesia: pros and cons of supplementary oxygen]

The routine administration of supplemental oxygen to women undergoing elective caesarean section under regional anesthesia in order to optimize oxygen supply to the fetus is common anesthetic practice in many German hospitals. However, this practice has been controversially discussed in the non-German literature for many years. This review presents and discusses the pros and cons of routinely providing supplemental oxygen to a parturient during caesarean section on the basis of the literature published over the last 30 years. Proponents of routine oxygen administration point to potential and unforeseeable risks of caesarean sections and consider the prophylactic administration of oxygen based on physiological considerations to be advantageous in terms of patient safety. Interestingly, data regarding the effects of an increased maternal FIO2 on improvement of fetal oxygenation are inconsistent, therefore, no unambiguous recommendation concerning which FIO2 to choose can be given. Opponents of routine oxygen supplementation allude above all to an increase in free radical activity in both mother and fetus; however, data in this respect are not consistent either. As supplemental oxygen to patients undergoing elective caesarean section without any risk factors under regional anesthesia is associated with potential risks while no advantage has so far been demonstrated, routine administration of oxygen has to be challenged and is no longer considered to be indicated by many. On the contrary, in cases of emergency with a concomitant risk of hypoxia for mother and fetus, administration of oxygen is indispensable in the light of present data.

Pharmacotherapy in pregnancy; effect of ABC and SLC transporters on drug transport across the placenta and fetal drug exposure

Pharmacotherapy during pregnancy is often inevitable for medical treatment of the mother, the fetus or both. The knowledge of drug transport across placenta is, therefore, an important topic to bear in mind when deciding treatment in pregnant women. Several drug transporters of the ABC and SLC families have been discovered in the placenta, such as P-glycoprotein, breast cancer resistance protein, or organic anion/cation transporters. It is thus evident that the passage of drugs across the placenta can no longer be predicted simply on the basis of their physical-chemical properties. Functional expression of placental drug transporters in the trophoblast and the possibility of drug-drug interactions must be considered to optimize pharmacotherapy during pregnancy. In this review we summarize current knowledge on the expression and function of ABC and SLC transporters in the trophoblast. Furthermore, we put this data into context with medical conditions that require maternal and/or fetal treatment during pregnancy, such as gestational diabetes, HIV infection, fetal arrhythmias and epilepsy. Proper understanding of the role of placental transporters should be of great interest not only to clinicians but also to pharmaceutical industry for future drug design and development to control the degree of fetal exposure.

Drug Interactions at the Human Placenta: What is the Evidence?

Pregnant women (and their fetuses) are treated with a significant number of prescription and non-prescription medications. Interactions among those drugs may affect their efficacy and toxicity in both mother and fetus. Whereas interactions that result in altered drug concentrations in maternal plasma are detectable, those involving modulation of placental transfer mechanisms are rarely reflected by altered drug concentrations in maternal plasma. Therefore, they are often overlooked. Placental-mediated interactions are possible because the placenta is not only a passive diffusional barrier, but also expresses a variety of influx and efflux transporters and drug-metabolizing enzymes. Current data on placental-mediated drug interactions are limited. In rodents, pharmacological or genetic manipulations of placental transporters significantly affect fetal drug exposure. In contrast, studies in human placentae suggest that the magnitude of such interactions is modest in most cases. Nevertheless, under certain circumstances, such interactions may be of clinical significance. This review describes currently known mechanisms of placental-mediated drug interactions and the potential implications of such interactions in humans. Better understanding of those mechanisms is important for minimizing fetal toxicity from drugs while improving their efficacy when directed to treat the fetus.

Susceptibility to a parkinsonian toxin varies during primate development

Symptoms of Parkinson's disease typically emerge later in life when loss of nigrostriatal dopamine neuron function exceeds the threshold of compensatory mechanisms in the basal ganglia. Although nigrostriatal dopamine neurons are lost during aging, in Parkinson's disease other detrimental factors must play a role to produce greater than normal loss of these neurons. Early development has been hypothesized to be a potentially vulnerable period when environmental or genetic abnormalities may compromise central dopamine neurons. This study uses a specific parkinsonian neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), to probe the relative vulnerability of nigrostriatal dopamine neurons at different stages of primate development. Measures of dopamine, homovanillic acid, 1-methyl-pyridinium concentrations and tyrosine hydroxylase immunoreactive neurons indicated that at mid-gestation dopamine neurons are relatively vulnerable to MPTP, whereas later in development or in the young primate these neurons are resistant to the neurotoxin. These studies highlight a potentially greater risk to the fetus of exposure during mid-gestation to environmental agents that cause oxidative stress. In addition, the data suggest that uncoupling protein-2 may be a target for retarding the progressive loss of nigrostriatal dopamine neurons that occurs in Parkinson's disease and aging.