Publications by authors named "Meakin A"

Introduction: Chronic fetal hypoxia is commonly associated with fetal growth restriction and can predispose to respiratory disease at birth and in later life. Antenatal antioxidant treatment has been investigated to overcome the effects of oxidative stress to improve respiratory outcomes. We aimed to determine if the effects of chronic fetal hypoxia and antenatal antioxidant administration persist in the lung in early adulthood.

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The mechanisms linking maternal asthma (MA) exposure in utero and subsequent risk of asthma in childhood are not fully understood. Pathological airway remodelling, including reticular basement membrane thickening, has been reported in infants and children who go on to develop asthma later in childhood. This suggests altered airway development before birth as a mechanism underlying increased risk of asthma in children exposed in utero to MA.

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The adult mammalian heart is unable to undergo cardiac repair, limiting potential treatment options after cardiac damage. However, the fetal heart is capable of cardiac repair. In preparation for birth, cardiomyocytes (CMs) undergo major maturational changes that include exit from the cell cycle, hypertrophic growth, and mitochondrial maturation.

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Maternal asthma is associated with increased rates of neonatal lung disease, and fetuses from asthmatic ewes have fewer surfactant-producing cells and lower surfactant-protein B gene (SFTPB) expression than controls. Antenatal betamethasone increases lung surfactant production in preterm babies, and we therefore tested this therapy in experimental maternal asthma. Ewes were sensitised to house dust mite allergen, and an asthmatic phenotype induced by fortnightly allergen lung challenges; controls received saline.

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Objective: Maternal obesity (MO) increases the risk of later-life liver disease in offspring, especially in males. This may be due to impaired cytochrome P450 (CYP) enzyme activity driven by an altered maternal-fetal hormonal milieu. MO increases fetal cortisol concentrations that may increase CYP activity; however, glucocorticoid receptor (GR)-mediated signaling can be modulated by alternative GR isoform expression.

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The consumption of high fat-high energy diets (HF-HEDs) continues to rise worldwide and parallels the rise in maternal obesity (MO) that predisposes offspring to cardiometabolic disorders. Although the underlying mechanisms are unclear, thyroid hormones (TH) modulate cardiac maturation in utero. Therefore, we aimed to determine the impact of a high fat-high energy diet (HF-HED) on the hormonal, metabolic and contractility profile of the non-human primate (NHP) fetal heart.

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Article Synopsis
  • - Current treatments for pregnancies at risk of preterm delivery involve maternal antenatal corticosteroid (ACS) therapy, which can improve lung maturity but negatively impact brain development, highlighting the need for new options.
  • - The study focused on the prodrug ciclesonide (CIC), which requires conversion to its active form (des-CIC) by specific enzymes in the human placenta; researchers analyzed gene expression and conversion rates in placenta samples from different gestational stages.
  • - Results indicated higher expression of certain enzymes in the second trimester compared to preterm and term births, but the conversion of CIC to des-CIC did not vary by gestational age, suggesting limited usefulness of CIC as a GR-agonist for preventing preterm birth,
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Increasing placental perfusion (PP) could improve outcomes of growth-restricted fetuses. One way of increasing PP may be by using phosphodiesterase (PDE)-5 inhibitors, which induce vasodilatation of vascular beds. We used a combination of clinically relevant magnetic resonance imaging (MRI) techniques to characterize the impact that tadalafil infusion has on maternal, placental and fetal circulations.

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  • Birthweight centile (BWC) below the 25th percentile is linked to higher risks of negative pregnancy outcomes, with males being particularly affected.
  • The study utilized RNA sequencing to analyze gene expression in male placentae at term, categorizing them by BWC (<10th, 10th-30th, >30th percentiles).
  • Findings revealed that lower BWC correlates with increased expression of androgen response elements and related gene sets, suggesting impaired placental function that may hinder fetal growth.
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  • Maternal obesity (MO) elevates fetal androgen levels and the risk of larger birth weights, particularly in male offspring, possibly due to altered liver enzyme activity during development.* -
  • The study involved feeding female baboons either a normal or high-fat diet before pregnancy and examining fetal liver samples to assess the activity of specific enzymes (CYP2B6, CYP3A) and expression of androgen receptor isoforms.* -
  • Results showed that male fetuses from the MO group had lower enzyme activity and reduced expression of the AR-45 receptor, suggesting that this could lead to increased androgen signaling and higher chances of larger birth size and later metabolic issues.*
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  • Babies with fetal growth restriction (FGR) face increased risk of cardiometabolic diseases, as FGR negatively impacts heart growth, metabolism, and function due to reduced nutrient supply during development.
  • Using a sheep model, researchers found that key proteins and genes involved in fatty acid transport and metabolism in the heart were significantly reduced in FGR fetuses, indicating impaired cardiac metabolic function.
  • Despite the diminished metabolic capacity and lower mitochondrial numbers in the hearts of FGR fetuses, these changes did not correlate with heart output, suggesting that altered metabolism may lead to poor cardiac health later in life for affected individuals.
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Background: The quality of Patient and Public Involvement (PPI) in healthcare research varies considerably and is frequently tokenistic. We aimed to co-produce the Insight | Public Involvement Quality Recognition and Awards programme, based on the UK Standards for Public Involvement (UKSPI) alongside an incremental scale designed by Expert Citizens (a lived experience-led community group), to incentivise and celebrate continuous improvement in PPI.

Methods: We used Task and Finish Groups (19/44 [43%] public contributor membership) to co-produce the programme which we piloted in three organisations with different healthcare research models.

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Article Synopsis
  • Babies born growth-restricted face higher risks for poor health outcomes both in the short and long term, and current treatments aren't effective in mitigating these risks.
  • Maternal treatment with resveratrol (RSV) may improve fetal conditions by increasing blood flow and oxygenation, but there are concerns that high polyphenol diets could negatively affect fetal blood circulation.
  • MRI studies showed that acute RSV exposure did not change fetal blood pressure, heart rate, or oxygen delivery, supporting its potential safety as a treatment for fetal growth restriction.
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Introduction: Drug metabolism during pregnancy is a complex process that involves maternal, placental and fetal sites of metabolism. Indeed, there is a lack of clarity provided from drug metabolism in human pregnancy due to ethical limitations. Large animal models of human pregnancy provide an opportunity to quantify activity of phase 1 drug metabolism mediated by cytochrome P450 (CYP) enzymes in the maternal, placental, and fetal compartments.

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  • Newborns exposed to sildenafil citrate (SC) in the womb show higher rates of persistent pulmonary hypertension, but the exact mechanism is unclear.
  • The study used MRI techniques to investigate how SC affects blood flow and oxygen delivery in fetal sheep.
  • Findings revealed increased pulmonary blood flow and oxygen delivery with SC, alongside reduced right to left heart shunting, suggesting that SC may contribute to poor pulmonary outcomes after birth.
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Hospital discharge for people experiencing homelessness is a perennial challenge. The Homeless Reduction Act 2017 (HRA) places new responsibilities on hospitals, but it remains unknown whether this has affected discharge practices. This qualitative study explores stakeholders' views on the challenges around hospital discharge for people experiencing homelessness, in the context of a deprived English city.

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Background: Maternal undernutrition during pregnancy disrupts both fetal growth and development with perturbations to certain physiological processes within the maternal-fetal-placental unit, including metabolic function. However, it is unknown if hypoglycemia during pregnancy alters maternal-fetal-placental drug metabolism as mediated by cytochrome P450 (CYP) enzymes. Despite this, hypoglycemia reduces CYP enzyme activity in non-pregnant animals.

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Introduction: The mechanisms that contribute to continued male intrauterine growth in response to an adverse maternal environment, such as those brought on by maternal asthma, remain largely undefined but may, in part, be mediated by androgen-mediated signalling. We previously reported the expression of multiple AR protein isoforms in the human placenta and proposed the novel AR-45 isoform to be integral in mediating male-specific androgen-dependent signalling in the presence of maternal asthma. In the current study we have used an ex vivo approach to further understand sex-specific differences in placental androgen signalling in the presence and absence of inflammation using human term villous placental explants.

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Introduction: Non-alcoholic fatty liver disease (NAFLD) is characterised by accumulation of triglycerides and cholesterol within the liver and dysregulation of specific hepatic cytochrome P450 (CYPs) activity. CYPs are involved in the metabolism of endogenous and exogenous chemicals. Hepatic CYP activity is dysregulated in human studies and animal models of a Western diet (WD) or low birth weight (LBW) independently, but the additive effects of LBW and postnatal WD consumption are unknown.

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Purpose: Ten percent of pregnancies are affected by intrauterine growth restriction (IUGR), and evidence suggests that affected neonates have reduced activity of hepatic cytochrome P450 (CYP) drug metabolising enzymes. Given that almost all pregnant individuals take medications and additional medications are often required during an IUGR pregnancy, we aimed to determine the impact of IUGR on hepatic CYP activity in sheep fetuses and pregnant ewes.

Methods: Specific probes were used to determine the impact of IUGR on the activity of several CYP isoenzymes (CYP1A2, CYP2C19, CYP2D6 and CYP3A) in sheep fetuses and pregnant ewes.

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It is well understood that sex differences exist between females and males even before they are born. These sex-dependent differences may contribute to altered growth and developmental outcomes for the fetus. Based on our initial observations in the human placenta, we hypothesised that the male prioritises growth pathways in order to maximise growth through to adulthood, thereby ensuring the greatest chance of reproductive success.

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Introduction: The human placenta expresses multiple glucocorticoid receptor (GR) isoforms that may be partially regulated by the untranslated 5' exon 1 GR gene promoter region which consists of 9 different promoters and 13 splice variants. The objective of this study was to determine which GR exon 1 variants are expressed in the human placenta and relate these findings to GR mRNA and protein expression.

Methods: Placental extracts from pregnancies with or without the complication of maternal asthma and trophoblast cells exposed to an inflammatory challenge in vitro were examined using PCR and Western blot to measure GR exon 1 variants, GR splice variant mRNA and GR protein isoforms, respectively.

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Maternal asthma is known to impact intrauterine growth outcomes, which may be mediated, in part, by altered androgen signalling. Our aim was to explore whether the sheep placenta expresses androgen receptor (AR) isoforms and determine if the differential expression of AR protein isoforms is altered by maternal asthma. Four known AR isoforms were detected (AR-FL, AR-v1, AR-v7, and AR-45), and their expression and subcellular distribution was altered in the presence of maternal allergic asthma.

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Maternal alcohol consumption during pregnancy results in elevated vulnerability to intrauterine growth restriction, preterm birth, miscarriage, and stillbirth. Many of the detrimental effects of fetal alcohol exposure may be mediated through placental dysfunction; however, the exact mechanisms remain unknown. Here, we aimed to determine the effect of maternal alcohol exposure prior to and during early pregnancy on placental glucocorticoid receptor (GR) isoforms, associated GR regulated genes, and infant outcomes.

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Introduction: Asthma is a highly prevalent co-morbidity during pregnancy that can worsen as gestation progresses and is associated with several adverse perinatal outcomes. These adverse outcomes often result from uncontrolled asthma during pregnancy and acute asthma exacerbations that are associated with alterations in placental function and fetal growth.

Areas Covered: This paper will discuss how maternal asthma in pregnancy affects fetal growth and development which may alter future offspring health.

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