Academic literature on the topic 'QH301 Biology ; RG Gynecology and obstetrics'

Human epidemiological and experimental animal studies show that a poor intra-uterine environment induced by restricted maternal diet during pregnancy leads to persistent alterations in the metabolism and physiology of the offspring and an altered susceptibility to chronic disease in adult life such as cardiovascular disease and metabolic syndrome. This phenomenon has been termed fetal programming. In rats, maternal protein restriction (MPR) during pregnancy alters the expression of specific genes involved in lipid and carbohydrate homeostasis such as glucocorticoid receptor (GR) and peroxisomal proliferator-activated receptor–alpha (PPARα). Evidence is accumulating which indicates that persistent changes in the expression of GR and PPARα are mediated by changes in the epigenetic regulation of these genes within the offspring. Epigenetics refers to processes that stably alter gene activity without altering DNA sequence. DNA methylation and histone modification are the most significant epigenetic modifications. However the mechanism by which alterations in maternal diet can induce the altered epigenetic regulation of genes such as GR or PPARα is currently unknown. The aim therefore of this project was to investigate the role of the DNA methyltransferase1 (Dnmt1). Dnmt1 is essential for the maintenance of DNA methylation patterns in the induction of the altered epigenetic regulation of genes in response to maternal diet. We initially investigated the effect of MPR on Dnmt1 mRNA expression in heart, brain and spleen from control and protein restriction (PR) offspring on PN34. We found that MPR altered the expression of Dnmt1 and the de novo DNA methyltransferases Dnmt3a, and 3b in a tissue specific manner. The effect of MPR on the expression and methylation of GR and PPARα was also tissue specific. However, in most tissues examined there was not a simple inverse relationship between GR or PPARα expression and methylation or with levels of Dnmt1 expression. To assess how widespread the changes in gene expression induced by MPR are, microarray analysis was conducted in E8 embryos from control and PR fed dams and results were validated by RT-PCR. Results showed that only relatively small subsets of genes were affected by MPR or global dietary restriction (UN). Gene ontology analysis also revealed that similar pathways were altered under condition of both maternal PR and UN and interestingly one of the pathways altered by both maternal PR and UN was chromatin modification. In both PR and UN embryos on E8 a decrease in Dnmt1, Dnmt3a and 3b expression was observed as well as a decrease in the histone methyltransferases EZH2, Suv39H1 and the HDAC Sirt1 in the embryos from PR dams compared to controls. Alterations in the expression of the DNA and histone methyltransferases in response to MPR were accompanied by changes in DNA methylation and histone modification at the GR promoter as early as E14.

Hypertensive disorders of pregnancy are an increasingly common disorder in modern society. The increasing prevalence of women with pre-eclampsia superimposed on a background of chronic hypertension is a significant burden in modern society and is profoundly detrimental to both mother and child; during pregnancy and beyond. Little is understood about the development of these multifactorial hypertensive disorders, however there is increasing evidence that the manifestation of hypertensive disorders during pregnancy is not solely due to placental-derived dysfunctions and has important maternally-driven components. The stroke-prone spontaneously hypertensive (SHRSP) rat is a well-established model of human essential hypertension. SHRSP dams remain hypertensive throughout pregnancy and demonstrate an abnormal uterine artery structure and function at term. This project aimed to more fully characterise pregnancy in the SHRSP rat. The objectives were to assess maternal responses and determine how maternal hypertension impacts maternal and fetal well-being as well as placental development; to investigate the underlying genetic mechanisms behind the eventual abnormal pregnancy-dependent uterine artery remodelling; and, finally, to increase the maternal cardiovascular load in SHRSP pregnancy to establish a model of superimposed pre-eclampsia. In vivo and ex vivo techniques were used to characterise cardiovascular function in the hypertensive SHRSP and normotensive WKY rats during gestation, as well as assess pregnancy outcomes. The SHRSP dams were found to have similar cardiac function compared to WKY, yet there was evidence of impaired systemic vascular structure and function in late gestation and placental abnormalities. Nevertheless, the SHRSP maintained similar litter sizes to WKY and did not demonstrate any major impact on fetal growth. Further similarities between SHRSP and WKY pregnancy were revealed with the assessment of uterine artery function in early gestation. However, using RNA sequencing to elucidate the transcriptomic profiles of the uterine arteries, SHRSP were found to have strikingly different responses to pregnancy at the transcript expression level, compared to WKY. Finally, a model of superimposed pre-eclampsia was established by increasing the cardiovascular stress in the dam using angiotensin II infusion during pregnancy in SHRSP. This model had a significantly higher systolic and diastolic blood pressure than the already hypertensive SHRSP. The pregnancy-dependent increase in cardiac output, observed in SHRSP, was negated by AngII infusion and was reduced in the highest treatment group. These major cardiovascular impairments were observed alongside increased proteinuria and reduced fetal growth; all phenotypes found in severely pre-eclamptic women. This work has provided information on systemic and uterine specific vascular responses to pregnancy in SHRSP and WKY rats alongside detail of underlying transcriptional differences. This study was the first to examine uterine artery gene expression changes during pregnancy. The different transcriptomic profiles of early pregnancy changes in the two strains make this an intriguing model to study maternal-driven vascular remodelling in hypertensive pregnancy. Furthermore, this work demonstrated that increasing the cardiovascular load during pregnancy in SHRSP successfully mimics superimposed pre-eclamptic phenotypes and could be used in the assessment of novel therapeutic strategies. To conclude, the SHRSP has the potential to aid our understanding of human pre-eclamptic conditions, especially when endeavouring to determine the impact of maternally-driven components of hypertensive disorders of pregnancy.

Embryo implantation represents a complex process vital in ensuring the normal development of pregnancy. Whether embryo implantation is the goal of natural conception or assisted reproductive treatment, the environment within the uterine cavity must be optimised in order to increase the chance of pregnancy. This thesis uses a mixture of research methods to investigate potential approaches to improving embryo implantation. Below are the key findings from this thesis: 1. The vitamin D status in women undergoing assisted reproductive treatment is important. An interventional trial would prove or disprove the merits of vitamin D deficiency treatment in these women. 2. There is not enough evidence to suggest a clear association between vitamin D and recurrent miscarriage, however there is a strong argument for biological plausibility. 3. The use of endometrial fluid collected at the time of embryo transfer in women undergoing assisted reproductive treatments for metabolomics analysis is possible. 4. Women with hydrosalpinx associated tubal infertility should be offered salpingostomy as a treatment option as the natural conception rates are similar to that achieved in in vitro fertilisation treatment.

The menopause is associated with a deficiency of reproductive hormones, and accompanied by a significant loss of bone mass. This bone loss is accelerated within the first five years post-menopause. Muscle strength at this time would have important clinical implications for correcting imbalance and preventing falls. The aim of the studies within this thesis were to 1) determine the rate and time course of force loss of the quadriceps muscle group over 12 months in three groups of women with varying hormonal status 2) establish the role of oestrogen in this weakness and 3) investigate the effectiveness of hormone replacement therapy (HRT) in maintaining muscle function. The reliability of an isokinetic dynamometer and a strain gauge assembly was examined initially to determine the inherent variability of muscle function assessment. Strength of the knee extensors measured on the isokinetic dynamometer was deemed reliable in middle-aged women, although at 1.05 rad/s more practice trials were needed to attain peak torque. Measurements of the knee flexors were highly variable. Maximal voluntary isometric contractions were repeatable using the strain gauge system, for both the knee extensors and first dorsal interosseus (FOI) muscle. There was greater variability in force production generated from electrically stimulated contractions. Maximal strength of the knee extensors declined by 9.3-4.6 and I0.3?3.1% (mean?SE) for dynamic (1.05 radls) and isometric strength respectively over 9 months in hypoestrogenic post-menopausal women. There were no changes at higher angular velocities, or for handgrip strength. These results support the role of reproductive hormones in influencing force production, which is further endorsed by the observation that females on HRT did not experience a reduction in strength over this time. The force loss was significant only when the post-menopausal and HRT group were compared (p < 0.05). The postmenopausal group were within I to 3 years past the menopause, the time period in which bone loss is rapid. This rapid loss of strength would therefore be expected to level out, similarly to bone. The menopause is an oestrogen-deficient and progesterone-deficient endocrinopathy. It is not possible to identify which hormone, if not both, is responsible for these observed changes in strength. To explore the relationship between acute changes in oestrogen and progesterone and strength, maximal force production of the quadriceps and first dorsal interosseus (FOI) was measured across the menstrual cycle. Maximal strength of the quadriceps was lowest prior to the surge in luteinizing hormone (LH) and reached its peak mid-luteal, a difference of 12.6?4.3% (mean?SE). These changes were significantly different (p < O.OS). From these results, there does not appear to be a role of unopposed oestrogen influencing force production but the pattern of strength changes implicates progesterone. There were no corresponding fluctuations in strength of the FOI, which remained relatively stable across the menstrual cycle. The contractility and fatigue resistance of the quadriceps did not differ significantly between any phase (p > O.OS).The difficulty in isolating oestrogen during the menstrual cycle does not render this a good model to assess its effects upon force production. Maximal strength and fatiguability of the FDI were examined in young women undergoing in vitro fertilisation (IVF) treatment when acute, massive changes in oestrogen are induced. There were no differences in muscle function of the FDI when assessed under very low or high oestrogen changes (p > O.05). The independent effects of oestrogen upon muscle function were not demonstrated here. Hormone replacement therapy is the most efficacious treatment for preventing menopausally-related bone loss. The results from the longitudinal study suggest that HRT confers protection against muscle weakness as a consequence of ovarian failure. Whether HRT maintains or restores strength was examined in the FDI of post-menopausal women (n=9). The oestrogen only and oestrogen-progestogen phases were compared with baseline measurements. A positive change in strength was observed, although this did not reach significance (p < O.1). The increase in strength (15.2±20.6%) between baseline and the oestrogen-progestogen phase of HRT corroborates the involvement of progesterone in determining muscle function. The findings suggest that the menopause is associated with a loss of strength, prevented by the administration of HRT. Oestrogen alone does not influence force production, although progesterone is implicated. This has important ramifications in hysterectomised women who are prescribed preparations containing oestrogen only.

The contribution of store-operated calcium entry (SOCE) in the response of human sperm to progesterone, a steroid secreted from the cumulus cells surrounding the oocyte, has not yet been elucidated. The aim of this study was to investigate the presence of SOCE proteins in human sperm and examine the effects of pharmacological modulation of SOCE on the progesterone-induced biphasic intracellular calcium concentration ([Ca\(^{2+}\)]i) response. STIM (stromal interacting molecule) and Orai, proteins of the SOCE system were detected in human sperm in a similar location to intracellular Ca\(^{2+}\) stores. 2-aminoethyldiphenyl borate (2-APB; SOCE modulator) altered SOCE in human sperm in a bimodal manner as seen in other cell types. Furthermore, 5\(\mu\)M 2-APB potentiated the initial progesterone-induced [Ca\(^{2+}\)]i transient within the neck and midpiece, but not in the flagellum. In the sustained phase of the progesterone-induced [Ca\(^{2+}\)]i response both 5\(\mu\)M 2-APB and 10\(\mu\)M loperamide (another modulator of SOCE) potentiated the [Ca\(^{2+}\)]i response. Higher doses of 2-APB (50-200\(\mu\)M) didn’t potentiate the transient [Ca\(^{2+}\)]i and inhibited the sustained response consistent with reported actions on SOCE. Ryanodine receptors were localised to the neck/midpiece region which suggested that they may mobilise intracellular Ca\(^{2+}\) stores in response to progesterone, leading to activation of STIM/Orai and initiating SOCE.

Tolerance of the semi-allogeneic fetus presents a significant challenge to the maternal immune system. The effect of pregnancy on maternal cellular immunity was established by assessing maternal effector and regulatory T-cell subsets during human pregnancy. This demonstrated that an increase in maternal peripheral regulatory T-cells or a shift from a Th1 to Th2 phenotype was not a requirement for normal pregnancy. We also determined the profound impact of maternal Cytomegalovirus seropositivity on maternal T- cell dynamics. T-cells with specificity for fetal epitopes have been detected in women with a history of pregnancy but it has been thought that such fetal specific cells were deleted during pregnancy. We identified, using MHC-peptide multimers, fetal-specific CD8 T-cells in half of all pregnancies. The fetal-specific response increased during pregnancy and persisted in the post natal period. Fetal-specific cells demonstrated an effector memory phenotype and retained functional potential. These data show that the development of a fetal-specific adaptive cellular immune response is a normal consequence of human pregnancy. Women with recurrent miscarriage were found to have abnormal T-cell function, with increased IFN\(\gamma\) and Il-17 production. Fetal specific T-cells were also detected in this cohort and progesterone attenuated their function, which may have therapeutic implications.

I investigated the role of genetic, environmental and intrauterine factors in child development using data from two large twin studies; the East Flanders Prospective Twin Survey (EFPTS) and the Twins and Multiple Births Association Heritability Study (TAMBAHS). An association between birth weight and child development has already been established. Potential associations between other factors of the intrauterine environment and child development were investigated in this thesis. Heritabilities of the umbilical cord, IQ, temperament and behaviour problems were estimated. Fetal characteristics, such as birth weight, placental weight and morphology, umbilical cord knots, length and insertions were investigated in relation to cognitive development in the EFPTS study. The impact of maternal pre-pregnancy weight on temperament and behaviour problems was examined in the TAMBAHS study. High heritability estimates were observed for certain dimensions of the umbilical cord, temperament and IQ; for behaviour problems, genetic, shared and non-shared environment were important. Low birth weight and cord knotting was associated with lower IQ; an association was observed between maternal overweight and children aggressive behaviour. The results are discussed in the context of the Developmental Origins of Health and Disease (DOHaD) hypothesis, highlighting the role of the intrauterine environment in child development.

Hypertension is one of the most common medical conditions complicating pregnancy, with significant implications on maternal and perinatal morbidity and mortality. Abnormalities in placentation have been implicated as the primary pathology responsible for the development of hypertension during pregnancy and its effects such as pre-eclampsia and eclampsia. With advancing research, the focus is now gradually shifting towards abnormalities in the maternal vasculature, including endothelial damage/dysfunction and impaired repair as a probable cause for this, with the latter also being implicated in the development of cardiovascular disorders in later life in these women. Hypertensive disorders occur in 6-8% of pregnancies. They also determine and influence the development of cardiovascular disease (CVD) in the mother in later life. Hypertension, obesity, metabolic syndrome and CVD are commoner in women with pre-eclampsia and preterm deliveries, whereas the risk of cerebrovascular disease is much higher in those with recurrent spontaneous abortions. This research thesis is a study of the various processes occurring in the maternal vasculature, including angiogenesis, apoptosis, endothelial damage and regeneration/repair, the extra-cellular matrix and the haem oxygenase systems, the abnormalities that occur in them and their associations with hypertensive disorders of pregnancy and their complications.