Association of early and late maternal smoking during pregnancy with offspring body mass index at 4 to 5 years of age.

The objective was to investigate the association between early and late maternal smoking during pregnancy on offspring body mass index (BMI). We undertook a retrospective cohort study using linked records from the Women's and Children's Health Network in South Australia. Among a cohort of women delivering a singleton, live-born infants between January 2000 and December 2005 (n=7658), 5961 reported not smoking during pregnancy, 297 reported quitting smoking during the first trimester of pregnancy, and 1400 reported continued smoking throughout pregnancy. Trained nurses measured the height and weight of the children at preschool visits in a state-wide surveillance programme. The main outcome measure was age- and sex-specific BMI z-score. At 4 to 5 years, mean (s.d.) BMI z-score was 0.40 (1.05), 0.60 (1.07) and 0.65 (1.18) in children of mothers who reported never smoking, quitting smoking and continued smoking during pregnancy, respectively. Compared with the group of non-smokers, both quitting smoking and continued smoking were associated with an increase in child BMI z-score of 0.15 (95% confidence interval: 0.01-0.29) and 0.21 (0.13-0.29), respectively. A significant dose-response relationship was also observed between the number of cigarettes smoked per day on average during the second half of pregnancy and the increase in offspring BMI z-score (P<0.001). In conclusion, any maternal smoking in pregnancy, even if mothers quit, is associated with an increase in offspring BMI at 4 to 5 years of age.

Inter- and intra-subject variability of motor cortex plasticity following continuous theta-burst stimulation.

BACKGROUND: The potential of non-invasive brain stimulation (NIBS) for studying, and inducing, functionally relevant neuroplasticity is dependent on protocols that can induce lasting, robust and reliable effects. A current limiting factor is the large inter- and intra-subject variability in NIBS-induced neuroplastic responses. There has been some study of inter-subject response variability and factors that contribute to it; however, intra-subject response variability has, so far, received little investigation. OBJECTIVES: By testing participants on multiple occasions we aimed to (1) compare inter- and intra-subject variability of neuroplastic responses induced by continuous theta-burst stimulation (cTBS); (2) determine whether the transcranial magnetic stimulation (TMS) intensity used to measure cTBS-induced neuroplastic responses contributes to response variability; (3) determine whether assessment of factors known to influence response variability can be used to explain some of the variability in cTBS-induced neuroplastic responses across experimental sessions. METHODS: In three separate experimental sessions, motor-evoked potential (MEP) input-output (IO) curves were obtained before and after cTBS, and questionnaire-based assessments of physical activity and perceived stress were obtained. RESULTS: cTBS-induced MEP suppression was greatest at the upper end of the IO curve (150-180% resting motor threshold; RMT) and most consistent across subjects and across experimental sessions when assessed with a TMS intensity of 150% RMT. The magnitude of cTBS-induced MEP suppression evoked at 150% RMT correlated with self-reported perceived stress, but not with self-reported physical activity. CONCLUSIONS: The most reliable TMS intensity to probe cTBS-induced long-term depression (LTD)-like neuroplastic responses is 150% RMT. This is unlikely to simply be a ceiling effect and, we suggest, may be due to changes in the descending volley evoked at higher stimulus intensities. The perceived stress scale appears to be sufficiently sensitive to measure the influence of subject stress on LTD-like neuroplastic responses.

Expression of eight glucocorticoid receptor isoforms in the human preterm placenta vary with fetal sex and birthweight.

INTRODUCTION: Administration of betamethasone to women at risk of preterm delivery is known to be associated with reduced fetal growth via alterations in placental function and possibly direct effects on the fetus. The placental glucocorticoid receptor (GR) is central to this response and recent evidence suggests there are numerous isoforms for GR in term placentae. In this study we have questioned whether GR isoform expression varies in preterm placentae in relation to betamethasone exposure, fetal sex and birthweight. METHODS: Preterm (24-36 completed weeks of gestation, n = 55) and term placentae (>37 completed weeks of gestation, n = 56) were collected at delivery. Placental GR expression was examined using Western Blot and analysed in relation to gestational age at delivery, fetal sex, birthweight and betamethasone exposure. Data was analysed using non-parametric tests. RESULTS: Eight known isoforms of the GR were detected in the preterm placenta and include GRα (94 kDa), GRß (91 kDa), GRα C (81 kDa) GR P (74 kDa) GR A (65 kDa), GRα D1-3 (50-55 kDa). Expression varied between preterm and term placentae with a greater expression of GRα C in preterm placentae relative to term placentae. The only sex differences in preterm placentae was that GRα D2 expression was higher in males than females. There were no alterations in preterm placental GR expression in association with betamethasone exposure. DISCUSSION: GRα C is the isoform involved in glucocorticoid induced apoptosis and suggests that its predominance in preterm placentae may contribute to the pathophysiology of preterm birth.

Early red cell transfusion favourably alters cerebral oxygen extraction in very preterm newborns.

BACKGROUND: Elevated cerebral fractional tissue oxygen extraction (cFTOE; ≥0.4) predicts early brain injury in very preterm infants. While blood transfusion increases oxygen-carrying capacity, its ability to improve cerebral oxygen kinetics in the immediate newborn period remains unknown. OBJECTIVE: To investigate the effect of red blood cell (RBC) transfusion in the first 24 h of life on cFTOE in infants ≤29 weeks gestation. METHODS: cFTOE was calculated from cerebral tissue oxygenation index (TOI) and cutaneous oximetry measured over a 30 min epoch before and after transfusion. Infants were dichotomised according to pre-transfusion cFTOE (low <0.4 vs high ≥0.4). RESULTS: 24 babies were included, 12 in each group. Pre- and post-transfusion Hb were similar between the groups. cFTOE significantly reduced after transfusion in the high but not low-extraction group (p<0.01). CONCLUSIONS: Early RBC transfusion favourably alters cerebral oxygen kinetics in infants with elevated cFTOE, showing potential for modification of the risk of hypoxic (brain) injury.

The human placenta expresses multiple glucocorticoid receptor isoforms that are altered by fetal sex, growth restriction and maternal asthma.

INTRODUCTION: We have previously identified sex-specific differences in the fetal-placental response to cortisol. Our recent studies suggest that this differential response to cortisol is driven by differences in glucocorticoid receptor (GR) protein function rather than through changes in gene transcription or protein expression. METHODS: This study was designed to define whether the human placenta expresses different isoforms of the GR and whether expression was altered by fetal sex and maternal asthma. Asthma and non-asthma pregnant women were prospectively recruited at their first antenatal visit and placentae collected at delivery. Placental GR expression was examined in relation to maternal asthma, fetal sex and birthweight. RESULTS: Twelve specific bands for the GR were identified at molecular weights of 94, 91, 81, 74, 69, 68, 65, 60, 55, 50, 48 and 38 kDa. The 12 isoforms were localised to the placental trophoblast and expression varied in relation to cellular location in either the cytoplasm or nucleus, fetal sex, fetal size and the presence and absence of maternal asthma. CONCLUSION: This is the first study to identify the presence of several protein isoforms of the GR in the human placenta. The data suggest glucocorticoid resistance observed in male placentae may be mediated through increased GRß, GR A and GR P localisation to the nucleus. While female placentae may be more sensitive to cortisol in the presence of maternal asthma through a decrease in GRß and an enhancement GRα activity via an interaction with GRα D3 and GRα C.

Placental P-glycoprotein is unaffected by timing of antenatal glucocorticoid therapy but reduced in SGA preterm infants.

INTRODUCTION: The beneficial effects of antenatal glucocorticoid therapy on fetal lung maturation require their passage across the placental glucocorticoid barrier, composed of glucocorticoid metabolising enzymes, such as 11 beta hydroxysteroid dehydrogenase (11ßHSD), and proteins that efflux glucocorticoids, such as P-glycoprotein (P-gp). We have shown that 11ßHSD2 activity is responsive to antenatal glucocorticoids, however the effect on placental P-gp remains unknown. Since antenatal glucocorticoids have a greater prophylactic effect in females compared to males, we also assessed whether this therapy induced sexually dimorphic effects on P-gp expression, as well as on placental inflammatory processes mediated by corticosteroids. METHODS: Placentas were collected from 53 women presenting in threatened preterm labour, and processed to assess cytokine and P-gp mRNA expression, as well as P-gp localisation using immunohistochemistry. RESULTS: Placental cytokine, P-gp mRNA and protein expression were not altered by timing of antenatal glucocorticoids or fetal sex. However, both P-gp mRNA and protein expression were significantly reduced in placentas from infants born small for gestational age (SGA) compared to appropriately grown infants (p < 0.05), suggesting a role for P-gp in its pathogenesis via the provision of a net increase in fetal exposure to bioactive exogenous glucocorticoids. CONCLUSIONS: While this study identified no change in placental P-gp following antenatal glucocorticoids, it has provided evidence that P-gp plays an important role in cases of SGA. This supports the known mechanistic relationship between antenatal glucocorticoids, fetal development and the postnatal phenotype. Given that P-gp also confers fetal protection from a number of drugs, this finding warrants further investigation to improve clinical management of the SGA fetus.

Localisation and characterisation of uncoupling protein-2 (UCP2) in the human preterm placenta.

The increase in oxidative stress during pregnancy is associated with increased placental antioxidant enzyme activity and may additionally be limited by the uncoupling proteins (UCPs). There is little data on the expression and localisation of UCP2 in the human preterm placenta or on its role in the regulation of placental oxidative stress. Placentae were collected from women with singleton pregnancies who delivered between 24 and 36 weeks gestation (n = 54) and from a term reference group who delivered following uncomplicated pregnancy (n = 11). UCP2 expression and localisation was determined by quantitative real-time RTPCR using Taqman gene expression assays and immunohistochemistry. Placental lipid hydroperoxide and nitrotyrosine content was determined by ELISA. UCP2 mRNA expression increased from 24 to 41 weeks gestation (p < 0.001) and was positively correlated with placental weight (p = 0.004). While UCP2 expression was lower in small for gestational age infants (p = 0.045) it did not differ with respect to timing of antenatal betamethasone exposure nor with placental lipid hydroperoxide or nitrotyrosine content. UCP2 staining was identified in the cytotrophoblast in 34% of samples and in the syncytiotrophoblast in 63% of samples. Cytotrophoblast staining was more frequent in later gestations (p = 0.03) with syncytiotrophoblast UCP2 staining was not altered by gestation. In the preterm group, no association was observed with time since antenatal betamethasone exposure or placental lipid hydroperoxide or nitrotyrosine content. The current data supports gestation dependant alterations in UCP2 mRNA expression and immunohistochemical localisation in the human placenta but no evidence for an important role for UCP2 in protection against placental oxidative damage.

Review: The feto-placental unit, pregnancy pathology and impact on long term maternal health.

Pregnancy induces a number of alterations to maternal physiology to accommodate the increased demands made by the developing fetus and placenta. These alterations appear at least in part to be driven by products derived from the feto-placental unit, including microchimeric cells, as well as placental exosomes and microparticles, inducing changes to maternal physiology both during pregnancy and beyond. Further, increasing evidence suggests that some of these alterations are dependent on the sex of the fetus. Pre-eclampsia and asthma represent two common pregnancy complications that have provided valuable insight into how the feto-placental unit influences maternal physiology in a sex-specific manner. Pregnancy-induced alterations in maternal physiology may expose pre-existing subclinical pathologies and provide insight into future maternal health and disease. While most pregnancy-induced alterations to the maternal system are reversed following delivery, some can persist after parturition leading to cardiovascular, metabolic and autoimmune disease and increased risk of early mortality.

Influence of sex and glucocorticoid exposure on preterm placental pro-oxidant-antioxidant balance.

Glucocorticoids (GC) are known to influence fetal ROS production and anti-oxidant defences yet little attention has focused on the potential for effects in the placenta. We hypothesised that antenatal GC exposure alters placental pro-oxidant-anti-oxidant balance sex-specifically, based upon the known relationship between male sex and poor pregnancy outcome. Placentae were collected from 60 women who delivered between 24 and 31 completed weeks gestation and placental oxidative and nitrative stress (protein carbonyl, lipid hydroperoxide, and nitrotyrosine concentration) and anti-oxidant enzyme activity (glutathione peroxidase, thioredoxin reductase, and superoxide dismutase) measured. A pro-oxidant state was observed in placentae of male compared to female infants born within 72 h of antenatal GC exposure, with higher levels of protein carbonyl content (p = 0.04), lipid hydroperoxide (p < 0.01) and nitrotyrosine content (p = 0.02), and lower levels of glutathione peroxidase activity (p = 0.01). A pro-oxidant state continued to be observed in placentae of males compared to females born outside of 72 h, with higher protein carbonyl content (p = 0.04) and lower glutathione peroxidase activity (p = 0.01) than females, however no differences in placental lipid hydroperoxide and nitrotyrosine content were observed. These sex-specific alterations in products of placental oxidative stress could not purely be explained by differences in clinical illness severity (CRIB2 score). Therefore, these sex-specific alterations in placental pro-oxidant-antioxidant balance in response to antenatal betamethasone exposure, independent of illness severity, could contribute to the patho-physiologic processes underlying oxygen radical diseases of the newborn, conditions known to exhibit a male excess.

The presence of maternal asthma during pregnancy suppresses the placental pro-inflammatory response to an immune challenge in vitro.

The mechanisms that contribute to adverse outcomes for the neonate in pregnancies complicated by asthma may be mediated via changes in placental immune function. This study was designed to determine whether the presence of maternal asthma during pregnancy alters the placental pro-inflammatory immune response in vitro. A prospective cohort study of women with asthma (n = 22) and control (n = 11) subjects had placentae collected immediately after delivery. Placental explants were exposed to an immune challenge, lipopolysaccharide, in the presence and absence of cortisol in vitro. Cytokines, glucocorticoid receptor α (GR α) and p38 MAPK protein were measured. Placentae of control pregnancies had an increase in pro-inflammatory cytokine production over a 24 h period. Placentae from pregnancies complicated by maternal asthma had a reduced pro-inflammatory cytokine response to an immune challenge relative to the controls especially in relation to the production of interleukin (IL)-1ß and TNFα regardless of fetal sex. Cortisol inhibition of placental cytokine production was dependent on timing of exposure, fetal sex and presence and absence of asthma. GRα and p38 MAPK protein expression did not appear to contribute to differences in response to endotoxin or cortisol. Maternal asthma during pregnancy induces a hyposensitive inflammatory state in the placenta which is regulated by cortisol in a sexually dimorphic manner.